ci: 👷 CI system updated

build(deps): bump github.com/valyala/fasthttp from 1.54.0 to 1.55.0 in the gomod group

.devcontainer/devcontainer.json

@@ -0,0 +1,18 @@
+{
+  "$schema": "https://raw.githubusercontent.com/devcontainers/spec/main/schemas/devContainer.base.schema.json",
+  "name": "default",
+  "image": "golang:1.22-bookworm",
+  "features": {
+    "ghcr.io/guiyomh/features/golangci-lint:0": {},
+    "ghcr.io/devcontainers/features/github-cli:1": {},
+    "ghcr.io/devcontainers/features/sshd:1": {}
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "streetsidesoftware.code-spell-checker"
+      ]
+    }
+  },
+  "postCreateCommand": "go mod download"
+}

.github/workflows/release.yml

@@ -44,6 +44,16 @@ jobs:
           path: out/
           if-no-files-found: error
           retention-days: 1
+      - if: matrix.os == 'linux' && matrix.arch == 'amd64'
+        working-directory: ./out
+        run: zip -r ./../templates.zip .
+      - if: matrix.os == 'linux' && matrix.arch == 'amd64'
+        uses: svenstaro/upload-release-action@v2
+        with:
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          file: templates.zip
+          asset_name: error-pages-static.zip
+          tag: ${{ github.ref }}
 
   demo:
     name: Update the demo (GitHub Pages)
@@ -76,20 +86,19 @@ jobs:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      - uses: docker/build-push-action@v5
+      - uses: docker/build-push-action@v6
         with:
           context: .
           file: Dockerfile
           push: true
           platforms: linux/amd64,linux/arm/v7,linux/arm64/v8
           build-args: "APP_VERSION=${{ steps.slug.outputs.version }}"
-          tags: ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version }}
-#         tags: | # TODO: uncomment after the stable release
-#           tarampampam/error-pages:latest
-#           tarampampam/error-pages:${{ steps.slug.outputs.version }}
-#           tarampampam/error-pages:${{ steps.slug.outputs.version-major }}.${{ steps.slug.outputs.version-minor }}
-#           tarampampam/error-pages:${{ steps.slug.outputs.version-major }}
-#           ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:latest
-#           ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version }}
-#           ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version-major }}.${{ steps.slug.outputs.version-minor }}
-#           ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version-major }}
+          tags: |
+            tarampampam/error-pages:latest
+            tarampampam/error-pages:${{ steps.slug.outputs.version }}
+            tarampampam/error-pages:${{ steps.slug.outputs.version-major }}.${{ steps.slug.outputs.version-minor }}
+            tarampampam/error-pages:${{ steps.slug.outputs.version-major }}
+            ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:latest
+            ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version }}
+            ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version-major }}.${{ steps.slug.outputs.version-minor }}
+            ghcr.io/${{ github.actor }}/${{ github.event.repository.name }}:${{ steps.slug.outputs.version-major }}

.github/workflows/tests.yml

@@ -83,7 +83,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - {uses: gacts/github-slug@v1, id: slug}
-      - uses: docker/build-push-action@v5
+      - uses: docker/build-push-action@v6
         with:
           context: .
           file: Dockerfile

Dockerfile

@@ -3,7 +3,7 @@
 # -✂- this stage is used to develop and build the application locally -------------------------------------------------
 FROM docker.io/library/golang:1.22-bookworm AS develop
 
-# use the /var/tmp as the GOPATH to reuse the modules cache
+# use the /var/tmp/go as the GOPATH to reuse the modules cache
 ENV GOPATH="/var/tmp/go"
 
 RUN set -x \
@@ -45,7 +45,7 @@ FROM docker.io/library/alpine:3.20 AS rootfs
 WORKDIR /tmp/rootfs
 
 # prepare rootfs for runtime
-RUN --mount=type=bind,source=.,target=/src set -x \
+RUN set -x \
     && mkdir -p ./etc ./bin \
     && echo 'appuser:x:10001:10001::/nonexistent:/sbin/nologin' > ./etc/passwd \
     && echo 'appuser:x:10001:' > ./etc/group
@@ -69,7 +69,7 @@ ARG APP_VERSION="undefined@docker"
 LABEL \
     # docs: https://github.com/opencontainers/image-spec/blob/master/annotations.md
     org.opencontainers.image.title="error-pages" \
-    org.opencontainers.image.description="Static server error pages in the docker image" \
+    org.opencontainers.image.description="Pretty server's error pages" \
     org.opencontainers.image.url="https://github.com/tarampampam/error-pages" \
     org.opencontainers.image.source="https://github.com/tarampampam/error-pages" \
     org.opencontainers.image.vendor="tarampampam" \
@@ -87,6 +87,8 @@ WORKDIR /opt
 # to find out which environment variables and CLI arguments are supported by the application, run the app
 # with the `--help` flag or refer to the documentation at https://github.com/tarampampam/error-pages#readme
 
+ENV LOG_LEVEL="warn"
+
 # docs: https://docs.docker.com/reference/dockerfile/#healthcheck
 HEALTHCHECK --interval=10s --start-interval=1s --start-period=5s --timeout=2s CMD [\
   "/bin/error-pages", "--log-format", "json", "healthcheck" \

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/stretchr/testify v1.9.0
 	github.com/urfave/cli-docs/v3 v3.0.0-alpha5
 	github.com/urfave/cli/v3 v3.0.0-alpha9
+	github.com/valyala/fasthttp v1.55.0
 	go.uber.org/automaxprocs v1.5.3
 )
 
@@ -19,7 +20,6 @@ require (
 	github.com/rogpeppe/go-internal v1.12.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
-	github.com/valyala/fasthttp v1.55.0 // indirect
 	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect

internal/cli/app.go

@@ -25,7 +25,7 @@ func NewApp(appName string) *cli.Command { //nolint:funlen
 		logLevelFlag = cli.StringFlag{
 			Name:     "log-level",
 			Value:    logger.InfoLevel.String(),
-			Usage:    "logging level (" + strings.Join(logger.LevelStrings(), "/") + ")",
+			Usage:    "Logging level (" + strings.Join(logger.LevelStrings(), "/") + ")",
 			Sources:  cli.EnvVars("LOG_LEVEL"),
 			OnlyOnce: true,
 			Config:   cli.StringConfig{TrimSpace: true},
@@ -41,7 +41,7 @@ func NewApp(appName string) *cli.Command { //nolint:funlen
 		logFormatFlag = cli.StringFlag{
 			Name:     "log-format",
 			Value:    logger.ConsoleFormat.String(),
-			Usage:    "logging format (" + strings.Join(logger.FormatStrings(), "/") + ")",
+			Usage:    "Logging format (" + strings.Join(logger.FormatStrings(), "/") + ")",
 			Sources:  cli.EnvVars("LOG_FORMAT"),
 			OnlyOnce: true,
 			Config:   cli.StringConfig{TrimSpace: true},
@@ -80,7 +80,7 @@ func NewApp(appName string) *cli.Command { //nolint:funlen
 			serve.NewCommand(log),
 			build.NewCommand(log),
 			healthcheck.NewCommand(log, healthcheck.NewHTTPHealthChecker()),
-			perftest.NewCommand(log),
+			perftest.NewCommand(),
 		},
 		Version: fmt.Sprintf("%s (%s)", appmeta.Version(), runtime.Version()),
 		Flags: []cli.Flag{ // global flags

internal/cli/build/command.go

@@ -44,16 +44,18 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 		addCodeFlag     = shared.AddHTTPCodesFlag
 		disableL10nFlag = shared.DisableL10nFlag
 		createIndexFlag = cli.BoolFlag{
-			Name:    "index",
-			Aliases: []string{"i"},
-			Usage:   "generate index.html file with links to all error pages",
+			Name:     "index",
+			Aliases:  []string{"i"},
+			Usage:    "Generate index.html file with links to all error pages",
+			Category: shared.CategoryBuild,
 		}
 		targetDirFlag = cli.StringFlag{
 			Name:     "target-dir",
 			Aliases:  []string{"out", "dir", "o"},
-			Usage:    "directory to put the built error pages into",
+			Usage:    "Directory to put the built error pages into",
 			Value:    ".", // current directory by default
 			Config:   cli.StringConfig{TrimSpace: true},
+			Category: shared.CategoryBuild,
 			OnlyOnce: true,
 			Validator: func(dir string) error {
 				if dir == "" {

internal/cli/perftest/command.go

@@ -1,32 +1,59 @@
 package perftest
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"io"
-	"math/rand"
-	"net/http"
+	"math"
+	"os"
+	"os/exec"
 	"runtime"
-	"sync"
-	"sync/atomic"
+	"strconv"
 	"time"
 
 	"github.com/urfave/cli/v3"
 
 	"gh.tarampamp.am/error-pages/internal/cli/shared"
-	"gh.tarampamp.am/error-pages/internal/logger"
 )
 
+const wrkOneCodeTestLua = `
+local formats = { 'application/json', 'application/xml', 'text/html', 'text/plain' }
+
+request = function()
+		wrk.headers["User-Agent"] = "wrk"
+    wrk.headers["X-Namespace"] = "NAMESPACE_" .. tostring(math.random(0, 99999999))
+    wrk.headers["X-Request-ID"] = "REQ_ID_" .. tostring(math.random(0, 99999999))
+    wrk.headers["Content-Type"] = formats[ math.random( 0, #formats - 1 ) ]
+
+    return wrk.format("GET", "/500.html?rnd=" .. tostring(math.random(0, 99999999)), nil, nil)
+end
+`
+
+//nolint:lll
+const bombDifferentCodes = `
+local formats = { 'application/json', 'application/xml', 'text/html', 'text/plain' }
+
+request = function()
+		wrk.headers["User-Agent"] = "wrk"
+    wrk.headers["X-Namespace"] = "NAMESPACE_" .. tostring(math.random(0, 99999999))
+    wrk.headers["X-Request-ID"] = "REQ_ID_" .. tostring(math.random(0, 99999999))
+    wrk.headers["Content-Type"] = formats[ math.random( 0, #formats - 1 ) ]
+
+    return wrk.format("GET", "/" .. tostring(math.random(400, 599)) .. ".html?rnd=" .. tostring(math.random(0, 99999999)), nil, nil)
+end
+`
+
 // NewCommand creates `perftest` command.
-func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
+func NewCommand() *cli.Command { //nolint:funlen
 	var (
 		portFlag     = shared.ListenPortFlag
 		durationFlag = cli.DurationFlag{
 			Name:    "duration",
 			Aliases: []string{"d"},
-			Usage:   "duration of the test",
-			Value:   10 * time.Second, //nolint:mnd
+			Usage:   "Duration of test",
+			Value:   15 * time.Second, //nolint:mnd
 			Validator: func(d time.Duration) error {
 				if d <= time.Second {
 					return errors.New("duration can't be less than 1 second")
@@ -38,11 +65,28 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 		threadsFlag = cli.UintFlag{
 			Name:    "threads",
 			Aliases: []string{"t"},
-			Usage:   "number of threads",
-			Value:   max(2, uint64(runtime.NumCPU()/2)), //nolint:mnd
+			Usage:   "Number of threads to use",
+			Value:   max(2, uint64(math.Round(float64(runtime.NumCPU())/1.3))), //nolint:mnd
 			Validator: func(u uint64) error {
 				if u == 0 {
 					return errors.New("threads number can't be zero")
+				} else if u > math.MaxUint16 {
+					return errors.New("threads number can't be greater than 65535")
+				}
+
+				return nil
+			},
+		}
+		connectionsFlag = cli.UintFlag{
+			Name:    "connections",
+			Aliases: []string{"c"},
+			Usage:   "Number of connections to keep open",
+			Value:   max(16, uint64(runtime.NumCPU()*25)), //nolint:mnd
+			Validator: func(u uint64) error {
+				if u == 0 {
+					return errors.New("threads number can't be zero")
+				} else if u > math.MaxUint16 {
+					return errors.New("threads number can't be greater than 65535")
 				}
 
 				return nil
@@ -52,97 +96,47 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 
 	return &cli.Command{
 		Name:    "perftest",
-		Aliases: []string{"perf", "test"},
+		Aliases: []string{"perf", "benchmark", "bench"},
 		Hidden:  true,
-		Usage:   "Simple performance (load) test for the HTTP server",
-		Action: func(ctx context.Context, c *cli.Command) error { // TODO: use fasthttp.Client
-			var (
-				perfCtx, cancel = context.WithTimeout(ctx, c.Duration(durationFlag.Name))
-				startedAt       = time.Now()
-
-				wg      sync.WaitGroup
-				success atomic.Uint64
-				failed  atomic.Uint64
-			)
-
-			defer func() {
-				cancel()
-
-				log.Info("Summary",
-					logger.Uint64("success", success.Load()),
-					logger.Uint64("failed", failed.Load()),
-					logger.Duration("duration", time.Since(startedAt)),
-					logger.Float64("RPS", float64(success.Load()+failed.Load())/time.Since(startedAt).Seconds()),
-					logger.Float64("errors rate", float64(failed.Load())/float64(success.Load()+failed.Load())*100), //nolint:mnd
-				)
-			}()
-
-			log.Info("Running test",
-				logger.Uint64("threads", c.Uint(threadsFlag.Name)),
-				logger.Duration("duration", c.Duration(durationFlag.Name)),
-			)
-
-			var httpClient = &http.Client{
-				Transport: &http.Transport{MaxConnsPerHost: max(2, int(c.Uint(threadsFlag.Name))-1)}, //nolint:mnd
-				Timeout:   c.Duration(durationFlag.Name) + time.Second,
+		Usage:   "Performance (load) test for the HTTP server (locally installed wrk is required)",
+		Action: func(ctx context.Context, c *cli.Command) error {
+			var wrkBinPath, lErr = exec.LookPath("wrk")
+			if lErr != nil {
+				return fmt.Errorf("seems like wrk (https://github.com/wg/wrk) is not installed: %w", lErr)
 			}
 
-			for i := uint64(0); i < c.Uint(threadsFlag.Name); i++ {
-				wg.Add(1)
+			var runTest = func(scriptContent string) error {
+				if stdOut, stdErr, err := wrkRunTest(ctx,
+					wrkBinPath,
+					uint16(c.Uint(threadsFlag.Name)),
+					uint16(c.Uint(connectionsFlag.Name)),
+					c.Duration(durationFlag.Name),
+					uint16(c.Uint(portFlag.Name)),
+					scriptContent,
+				); err != nil {
+					var errData, _ = io.ReadAll(stdErr)
 
-				go func(log *logger.Logger) {
-					defer wg.Done()
+					return fmt.Errorf("failed to execute the test: %w (%s)", err, string(errData))
+				} else {
+					var outData, _ = io.ReadAll(stdOut)
 
-					if perfCtx.Err() != nil {
-						return
-					}
+					printf("Test completed successfully. Here is the output:\n\n%s\n", string(outData))
+				}
 
-					var req, rErr = makeRequest(perfCtx, uint16(c.Uint(portFlag.Name)))
-					if rErr != nil {
-						log.Error("Failed to create a new request", logger.Error(rErr))
-
-						return
-					}
-
-					for {
-						var sentAt = time.Now()
-
-						var resp, respErr = httpClient.Do(req)
-						if resp != nil {
-							if _, err := io.Copy(io.Discard, resp.Body); err != nil && !errIsDone(err) {
-								log.Error("Failed to read response body", logger.Error(err))
-							}
-
-							if err := resp.Body.Close(); err != nil && !errIsDone(err) {
-								log.Error("Failed to close response body", logger.Error(err))
-							}
-						}
-
-						if respErr != nil {
-							if errIsDone(respErr) {
-								return
-							}
-
-							log.Error("Request failed", logger.Error(respErr))
-							failed.Add(1)
-
-							continue
-						}
-
-						log.Debug("Response received",
-							logger.String("status", resp.Status),
-							logger.Duration("duration", time.Since(sentAt)),
-							logger.Int64("size", resp.ContentLength),
-							logger.Uint64("success", success.Load()),
-							logger.Uint64("failed", failed.Load()),
-						)
-
-						success.Add(1)
-					}
-				}(log.Named(fmt.Sprintf("thread-%d", i)))
+				return nil
 			}
 
-			wg.Wait()
+			printf("Starting the test to bomb ONE PAGE (code). Please, be patient...\n")
+
+			if err := runTest(wrkOneCodeTestLua); err != nil {
+				return err
+			}
+
+			printf("Starting the test to bomb DIFFERENT PAGES (codes). Please, be patient...\n")
+
+			if err := runTest(bombDifferentCodes); err != nil {
+				return err
+			}
 
 			return nil
 		},
@@ -150,54 +144,51 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 			&portFlag,
 			&durationFlag,
 			&threadsFlag,
+			&connectionsFlag,
 		},
 	}
 }
 
-// randomIntBetween returns a random integer between min and max.
-func randomIntBetween(min, max int) int { return min + rand.Intn(max-min) } //nolint:gosec
+func printf(format string, args ...any) { fmt.Printf(format, args...) } //nolint:forbidigo
 
-// makeRequest creates a new HTTP request for the performance test.
-func makeRequest(ctx context.Context, port uint16) (*http.Request, error) {
-	var req, rErr = http.NewRequestWithContext(ctx,
-		http.MethodGet,
-		fmt.Sprintf(
-			"http://127.0.0.1:%d/%d.html?rnd=%d", // for load testing purposes only
-			port,
-			randomIntBetween(400, 418),       //nolint:mnd
-			randomIntBetween(1, 999_999_999), //nolint:mnd
-		),
-		http.NoBody,
+func wrkRunTest(
+	ctx context.Context,
+	wrkBinPath string,
+	threadsCount, connectionsCount uint16,
+	duration time.Duration,
+	port uint16,
+	scriptContent string,
+) (io.Reader, io.Reader, error) {
+	var tmpFile, tErr = os.CreateTemp("", "ep-perf-one-page")
+	if tErr != nil {
+		return nil, nil, fmt.Errorf("failed to create a temporary file: %w", tErr)
+	}
+
+	defer func() {
+		_ = tmpFile.Close()
+		_ = os.Remove(tmpFile.Name())
+	}()
+
+	if _, err := tmpFile.WriteString(scriptContent); err != nil {
+		return nil, nil, fmt.Errorf("failed to write to a temporary file: %w", err)
+	}
+
+	if err := tmpFile.Close(); err != nil {
+		return nil, nil, err
+	}
+
+	var stdout, stderr bytes.Buffer
+
+	var cmd = exec.CommandContext(ctx, wrkBinPath, //nolint:gosec
+		"--timeout", "1s",
+		"--threads", strconv.FormatUint(uint64(threadsCount), 10),
+		"--connections", strconv.FormatUint(uint64(connectionsCount), 10),
+		"--duration", duration.String(),
+		"--script", tmpFile.Name(),
+		fmt.Sprintf("http://127.0.0.1:%d/", port),
 	)
 
-	if rErr != nil {
-		return nil, rErr
-	}
+	cmd.Stdout, cmd.Stderr = &stdout, &stderr
 
-	req.Header.Set("Connection", "keep-alive")
-	req.Header.Set("User-Agent", "perftest")
-	req.Header.Set("X-Namespace", fmt.Sprintf("namespace-%d", randomIntBetween(1, 999_999_999))) //nolint:mnd
-	req.Header.Set("X-Request-ID", fmt.Sprintf("req-id-%d", randomIntBetween(1, 999_999_999)))   //nolint:mnd
-
-	var contentType string
-
-	switch randomIntBetween(1, 4) { //nolint:mnd
-	case 1:
-		contentType = "application/json"
-	case 2: //nolint:mnd
-		contentType = "application/xml"
-	case 3: //nolint:mnd
-		contentType = "text/html"
-	default:
-		contentType = "text/plain"
-	}
-
-	req.Header.Set("Content-Type", contentType)
-
-	return req, nil
-}
-
-// errIsDone checks if the error is a context.DeadlineExceeded or context.Canceled.
-func errIsDone(err error) bool {
-	return errors.Is(err, context.DeadlineExceeded) || errors.Is(err, context.Canceled)
+	return &stdout, &stderr, cmd.Run() // execute
 }

internal/cli/serve/command.go

@@ -22,9 +22,9 @@ type command struct {
 
 	opt struct {
 		http struct { // our HTTP server
-			addr string
-			port uint16
-			// readBufferSize uint
+			addr           string
+			port           uint16
+			readBufferSize uint
 		}
 	}
 }
@@ -46,25 +46,28 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 		disableL10nFlag = shared.DisableL10nFlag
 		jsonFormatFlag  = cli.StringFlag{
 			Name: "json-format",
-			Usage: "override the default error page response in JSON format (Go templates are supported; the error " +
+			Usage: "Override the default error page response in JSON format (Go templates are supported; the error " +
 				"page will use this template if the client requests JSON content type)",
 			Sources:  env("RESPONSE_JSON_FORMAT"),
+			Category: shared.CategoryFormats,
 			OnlyOnce: true,
 			Config:   trim,
 		}
 		xmlFormatFlag = cli.StringFlag{
 			Name: "xml-format",
-			Usage: "override the default error page response in XML format (Go templates are supported; the error " +
+			Usage: "Override the default error page response in XML format (Go templates are supported; the error " +
 				"page will use this template if the client requests XML content type)",
 			Sources:  env("RESPONSE_XML_FORMAT"),
+			Category: shared.CategoryFormats,
 			OnlyOnce: true,
 			Config:   trim,
 		}
 		plainTextFormatFlag = cli.StringFlag{
 			Name: "plaintext-format",
-			Usage: "override the default error page response in plain text format (Go templates are supported; the " +
+			Usage: "Override the default error page response in plain text format (Go templates are supported; the " +
 				"error page will use this template if the client requests plain text content type or does not specify any)",
 			Sources:  env("RESPONSE_PLAINTEXT_FORMAT"),
+			Category: shared.CategoryFormats,
 			OnlyOnce: true,
 			Config:   trim,
 		}
@@ -72,17 +75,19 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 			Name:    "template-name",
 			Aliases: []string{"t"},
 			Value:   cfg.TemplateName,
-			Usage: "name of the template to use for rendering error pages (built-in templates: " +
+			Usage: "Name of the template to use for rendering error pages (built-in templates: " +
 				strings.Join(cfg.Templates.Names(), ", ") + ")",
 			Sources:  env("TEMPLATE_NAME"),
+			Category: shared.CategoryTemplates,
 			OnlyOnce: true,
 			Config:   trim,
 		}
 		defaultCodeToRenderFlag = cli.UintFlag{
-			Name:    "default-error-page",
-			Usage:   "the code of the default (index page, when a code is not specified) error page to render",
-			Value:   uint64(cfg.DefaultCodeToRender),
-			Sources: env("DEFAULT_ERROR_PAGE"),
+			Name:     "default-error-page",
+			Usage:    "The code of the default (index page, when a code is not specified) error page to render",
+			Value:    uint64(cfg.DefaultCodeToRender),
+			Sources:  env("DEFAULT_ERROR_PAGE"),
+			Category: shared.CategoryCodes,
 			Validator: func(code uint64) error {
 				if code > 999 { //nolint:mnd
 					return fmt.Errorf("wrong HTTP code [%d] for the default error page", code)
@@ -94,17 +99,19 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 		}
 		sendSameHTTPCodeFlag = cli.BoolFlag{
 			Name: "send-same-http-code",
-			Usage: "the HTTP response should have the same status code as the requested error page (by default, " +
+			Usage: "The HTTP response should have the same status code as the requested error page (by default, " +
 				"every response with an error page will have a status code of 200)",
 			Value:    cfg.RespondWithSameHTTPCode,
 			Sources:  env("SEND_SAME_HTTP_CODE"),
+			Category: shared.CategoryOther,
 			OnlyOnce: true,
 		}
 		showDetailsFlag = cli.BoolFlag{
 			Name:     "show-details",
-			Usage:    "show request details in the error page response (if supported by the template)",
+			Usage:    "Show request details in the error page response (if supported by the template)",
 			Value:    cfg.ShowDetails,
 			Sources:  env("SHOW_DETAILS"),
+			Category: shared.CategoryOther,
 			OnlyOnce: true,
 		}
 		proxyHeadersListFlag = cli.StringFlag{
@@ -122,14 +129,16 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 
 				return nil
 			},
+			Category: shared.CategoryOther,
 			OnlyOnce: true,
 			Config:   trim,
 		}
 		rotationModeFlag = cli.StringFlag{
 			Name:     "rotation-mode",
 			Value:    config.RotationModeDisabled.String(),
-			Usage:    "templates automatic rotation mode (" + strings.Join(config.RotationModeStrings(), "/") + ")",
+			Usage:    "Templates automatic rotation mode (" + strings.Join(config.RotationModeStrings(), "/") + ")",
 			Sources:  env("TEMPLATES_ROTATION_MODE"),
+			Category: shared.CategoryTemplates,
 			OnlyOnce: true,
 			Config:   trim,
 			Validator: func(s string) error {
@@ -140,23 +149,34 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 				return nil
 			},
 		}
+		readBufferSizeFlag = cli.UintFlag{
+			Name: "read-buffer-size",
+			Usage: "Per-connection buffer size in bytes for reading requests, this also limits the maximum header size " +
+				"(increase this buffer if your clients send multi-KB Request URIs and/or multi-KB headers (e.g., " +
+				"large cookies), note that increasing this value will increase memory consumption)",
+			Value:    1024 * 5, //nolint:mnd // 5 KB
+			Sources:  env("READ_BUFFER_SIZE"),
+			Category: shared.CategoryOther,
+			OnlyOnce: true,
+		}
 	)
 
 	// override some flag usage messages
-	addrFlag.Usage = "the HTTP server will listen on this IP (v4 or v6) address (set 127.0.0.1 for localhost, " +
+	addrFlag.Usage = "The HTTP server will listen on this IP (v4 or v6) address (set 127.0.0.1/::1 for localhost, " +
 		"0.0.0.0 to listen on all interfaces, or specify a custom IP)"
-	portFlag.Usage = "the TCP port number for the HTTP server to listen on (0-65535)"
+	portFlag.Usage = "The TCP port number for the HTTP server to listen on (0-65535)"
 
 	disableL10nFlag.Value = cfg.L10n.Disable // set the default value depending on the configuration
 
 	cmd.c = &cli.Command{
 		Name:    "serve",
 		Aliases: []string{"s", "server", "http"},
-		Usage:   "Start HTTP server",
+		Usage:   "Please start the HTTP server to serve the error pages. You can configure various options - please RTFM :D",
 		Suggest: true,
 		Action: func(ctx context.Context, c *cli.Command) error {
 			cmd.opt.http.addr = c.String(addrFlag.Name)
 			cmd.opt.http.port = uint16(c.Uint(portFlag.Name))
+			cmd.opt.http.readBufferSize = uint(c.Uint(readBufferSizeFlag.Name))
 			cfg.L10n.Disable = c.Bool(disableL10nFlag.Name)
 			cfg.DefaultCodeToRender = uint16(c.Uint(defaultCodeToRenderFlag.Name))
 			cfg.RespondWithSameHTTPCode = c.Bool(sendSameHTTPCodeFlag.Name)
@@ -282,6 +302,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 			&showDetailsFlag,
 			&proxyHeadersListFlag,
 			&rotationModeFlag,
+			&readBufferSizeFlag,
 		},
 	}
 
@@ -290,7 +311,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 
 // Run current command.
 func (cmd *command) Run(ctx context.Context, log *logger.Logger, cfg *config.Config) error { //nolint:funlen
-	var srv = appHttp.NewServer(log)
+	var srv = appHttp.NewServer(log, cmd.opt.http.readBufferSize)
 
 	if err := srv.Register(cfg); err != nil {
 		return err

internal/cli/serve/command_test.go

@@ -36,7 +36,7 @@ func TestCommand_Run(t *testing.T) {
 			"--add-template", "./testdata/foo-template.html",
 			"--disable-template", "ghost",
 			"--disable-template", "<unknown>",
-			"--add-http-code", "200=Code/Description",
+			"--add-code", "200=Code/Description",
 			"--json-format", "json format",
 			"--xml-format", "xml format",
 			"--plaintext-format", "plaintext format",

internal/cli/shared/flags.go

@@ -11,6 +11,15 @@ import (
 	"gh.tarampamp.am/error-pages/internal/config"
 )
 
+const (
+	CategoryHTTP      = "HTTP:"
+	CategoryTemplates = "TEMPLATES:"
+	CategoryCodes     = "HTTP CODES:"
+	CategoryFormats   = "FORMATS:"
+	CategoryBuild     = "BUILD:"
+	CategoryOther     = "OTHER:"
+)
+
 // Note: Don't use pointers for flags, because they have own state which is not thread-safe.
 // https://github.com/urfave/cli/issues/1926
 
@@ -20,6 +29,7 @@ var ListenAddrFlag = cli.StringFlag{
 	Usage:    "IP (v4 or v6) address to listen on",
 	Value:    "0.0.0.0", // bind to all interfaces by default
 	Sources:  cli.EnvVars("LISTEN_ADDR"),
+	Category: CategoryHTTP,
 	OnlyOnce: true,
 	Config:   cli.StringConfig{TrimSpace: true},
 	Validator: func(ip string) error {
@@ -41,6 +51,7 @@ var ListenPortFlag = cli.UintFlag{
 	Usage:    "TCP port number",
 	Value:    8080, // default port number
 	Sources:  cli.EnvVars("LISTEN_PORT"),
+	Category: CategoryHTTP,
 	OnlyOnce: true,
 	Validator: func(port uint64) error {
 		if port == 0 || port > 65535 {
@@ -53,9 +64,10 @@ var ListenPortFlag = cli.UintFlag{
 
 var AddTemplatesFlag = cli.StringSliceFlag{
 	Name: "add-template",
-	Usage: "to add a new template, provide the path to the file using this flag (the filename without the extension " +
+	Usage: "To add a new template, provide the path to the file using this flag (the filename without the extension " +
 		"will be used as the template name)",
-	Config: cli.StringConfig{TrimSpace: true},
+	Config:   cli.StringConfig{TrimSpace: true},
+	Category: CategoryTemplates,
 	Validator: func(paths []string) error {
 		for _, path := range paths {
 			if path == "" {
@@ -72,18 +84,19 @@ var AddTemplatesFlag = cli.StringSliceFlag{
 }
 
 var DisableTemplateNamesFlag = cli.StringSliceFlag{
-	Name:   "disable-template",
-	Usage:  "disable the specified template by its name (useful to disable the built-in templates and use only custom ones)",
-	Config: cli.StringConfig{TrimSpace: true},
+	Name:     "disable-template",
+	Usage:    "Disable the specified template by its name (useful to disable the built-in templates and use only custom ones)",
+	Config:   cli.StringConfig{TrimSpace: true},
+	Category: CategoryTemplates,
 }
 
 var AddHTTPCodesFlag = cli.StringMapFlag{
-	Name:    "add-http-code",
-	Aliases: []string{"add-code"},
-	Usage: "to add a new HTTP status code, provide the code and its message/description using this flag (the format " +
+	Name: "add-code",
+	Usage: "To add a new HTTP status code, provide the code and its message/description using this flag (the format " +
 		"should be '%code%=%message%/%description%'; the code may contain a wildcard '*' to cover multiple codes at " +
 		"once, for example, '4**' will cover all 4xx codes unless a more specific code is described previously)",
-	Config: cli.StringConfig{TrimSpace: true},
+	Config:   cli.StringConfig{TrimSpace: true},
+	Category: CategoryCodes,
 	Validator: func(codes map[string]string) error {
 		for code, msgAndDesc := range codes {
 			if code == "" {
@@ -128,7 +141,8 @@ func ParseHTTPCodes(codes map[string]string) map[string]config.CodeDescription {
 
 var DisableL10nFlag = cli.BoolFlag{
 	Name:     "disable-l10n",
-	Usage:    "disable localization of error pages (if the template supports localization)",
+	Usage:    "Disable localization of error pages (if the template supports localization)",
 	Sources:  cli.EnvVars("DISABLE_L10N"),
+	Category: CategoryOther,
 	OnlyOnce: true,
 }

internal/cli/shared/flags_test.go

@@ -122,7 +122,7 @@ func TestAddHTTPCodesFlag(t *testing.T) {
 
 	var flag = shared.AddHTTPCodesFlag
 
-	assert.Equal(t, "add-http-code", flag.Name)
+	assert.Equal(t, "add-code", flag.Name)
 
 	for name, tt := range map[string]struct {
 		giveValue  map[string]string

internal/config/config.go

@@ -72,7 +72,7 @@ const defaultJSONFormat string = `{
     "service_name": {{ service_name | json }},
     "service_port": {{ service_port | json }},
     "request_id": {{ request_id | json }},
-    "timestamp": {{ now.Unix }}
+    "timestamp": {{ nowUnix }}
   }{{ end }}
 }
 ` // an empty line at the end is important for better UX
@@ -91,7 +91,7 @@ const defaultXMLFormat string = `<?xml version="1.0" encoding="utf-8"?>
     <serviceName>{{ service_name }}</serviceName>
     <servicePort>{{ service_port }}</servicePort>
     <requestID>{{ request_id }}</requestID>
-    <timestamp>{{ now.Unix }}</timestamp>
+    <timestamp>{{ nowUnix }}</timestamp>
   </details>{{ end }}
 </error>
 ` // an empty line at the end is important for better UX
@@ -107,7 +107,7 @@ Ingress Name: {{ ingress_name }}
 Service Name: {{ service_name }}
 Service Port: {{ service_port }}
 Request ID: {{ request_id }}
-Timestamp: {{ now.Unix }}{{ end }}
+Timestamp: {{ nowUnix }}{{ end }}
 ` // an empty line at the end is important for better UX
 
 //nolint:lll

internal/http/handlers/error_page/cache.go

@@ -0,0 +1,111 @@
+package error_page
+
+import (
+	"bytes"
+	"crypto/md5" //nolint:gosec
+	"encoding/gob"
+	"sync"
+	"time"
+
+	"gh.tarampamp.am/error-pages/internal/template"
+)
+
+type (
+	// RenderedCache is a cache for rendered error pages. It's safe for concurrent use.
+	// It uses a hash of the template and props as a key.
+	//
+	// To remove expired items, call ClearExpired method periodically (a bit more often than the ttl).
+	RenderedCache struct {
+		ttl time.Duration
+
+		mu    sync.RWMutex
+		items map[[32]byte]cacheItem // map[template_hash[0:15];props_hash[16:32]]cache_item
+	}
+
+	cacheItem struct {
+		content     []byte
+		addedAtNano int64
+	}
+)
+
+// NewRenderedCache creates a new RenderedCache with the specified ttl.
+func NewRenderedCache(ttl time.Duration) *RenderedCache {
+	return &RenderedCache{ttl: ttl, items: make(map[[32]byte]cacheItem)}
+}
+
+// genKey generates a key for the cache item by hashing the template and props.
+func (rc *RenderedCache) genKey(template string, props template.Props) [32]byte {
+	var (
+		key    [32]byte
+		th, ph = hash(template), hash(props) // template hash, props hash
+	)
+
+	copy(key[:16], th[:]) // first 16 bytes for the template hash
+	copy(key[16:], ph[:]) // last 16 bytes for the props hash
+
+	return key
+}
+
+// Has checks if the cache has an item with the specified template and props.
+func (rc *RenderedCache) Has(template string, props template.Props) bool {
+	var key = rc.genKey(template, props)
+
+	rc.mu.RLock()
+	_, ok := rc.items[key]
+	rc.mu.RUnlock()
+
+	return ok
+}
+
+// Put adds a new item to the cache with the specified template, props, and content.
+func (rc *RenderedCache) Put(template string, props template.Props, content []byte) {
+	var key = rc.genKey(template, props)
+
+	rc.mu.Lock()
+	rc.items[key] = cacheItem{content: content, addedAtNano: time.Now().UnixNano()}
+	rc.mu.Unlock()
+}
+
+// Get returns the content of the item with the specified template and props.
+func (rc *RenderedCache) Get(template string, props template.Props) ([]byte, bool) {
+	var key = rc.genKey(template, props)
+
+	rc.mu.RLock()
+	item, ok := rc.items[key]
+	rc.mu.RUnlock()
+
+	return item.content, ok
+}
+
+// ClearExpired removes all expired items from the cache.
+func (rc *RenderedCache) ClearExpired() {
+	rc.mu.Lock()
+
+	var now = time.Now().UnixNano()
+
+	for key, item := range rc.items {
+		if now-item.addedAtNano > rc.ttl.Nanoseconds() {
+			delete(rc.items, key)
+		}
+	}
+
+	rc.mu.Unlock()
+}
+
+// Clear removes all items from the cache.
+func (rc *RenderedCache) Clear() {
+	rc.mu.Lock()
+	clear(rc.items)
+	rc.mu.Unlock()
+}
+
+// hash returns an MD5 hash of the provided value (it may be any built-in type).
+func hash(in any) [16]byte {
+	var b bytes.Buffer
+
+	if err := gob.NewEncoder(&b).Encode(in); err != nil {
+		return [16]byte{} // never happens because we encode only built-in types
+	}
+
+	return md5.Sum(b.Bytes()) //nolint:gosec
+}

internal/http/handlers/error_page/cache_test.go

@@ -0,0 +1,86 @@
+package error_page_test
+
+import (
+	"strconv"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"gh.tarampamp.am/error-pages/internal/http/handlers/error_page"
+	"gh.tarampamp.am/error-pages/internal/template"
+)
+
+func TestRenderedCache_CRUD(t *testing.T) {
+	t.Parallel()
+
+	var cache = error_page.NewRenderedCache(time.Millisecond)
+
+	t.Run("has", func(t *testing.T) {
+		assert.False(t, cache.Has("template", template.Props{}))
+		cache.Put("template", template.Props{}, []byte("content"))
+		assert.True(t, cache.Has("template", template.Props{}))
+
+		assert.False(t, cache.Has("template", template.Props{Code: 1}))
+		assert.False(t, cache.Has("foo", template.Props{Code: 1}))
+	})
+
+	t.Run("exists", func(t *testing.T) {
+		var got, ok = cache.Get("template", template.Props{})
+
+		assert.True(t, ok)
+		assert.Equal(t, []byte("content"), got)
+
+		cache.Clear()
+
+		assert.False(t, cache.Has("template", template.Props{}))
+	})
+
+	t.Run("not exists", func(t *testing.T) {
+		var got, ok = cache.Get("template", template.Props{Code: 2})
+
+		assert.False(t, ok)
+		assert.Nil(t, got)
+	})
+
+	t.Run("race condition provocation", func(t *testing.T) {
+		var wg sync.WaitGroup
+
+		for i := 0; i < 100; i++ {
+			wg.Add(2)
+
+			go func(i int) {
+				defer wg.Done()
+
+				cache.Get("template", template.Props{})
+				cache.Put("template"+strconv.Itoa(i), template.Props{}, []byte("content"))
+				cache.Has("template", template.Props{})
+			}(i)
+
+			go func() {
+				defer wg.Done()
+
+				cache.ClearExpired()
+			}()
+		}
+
+		wg.Wait()
+	})
+}
+
+func TestRenderedCache_Expiring(t *testing.T) {
+	t.Parallel()
+
+	var cache = error_page.NewRenderedCache(10 * time.Millisecond)
+
+	cache.Put("template", template.Props{}, []byte("content"))
+	cache.ClearExpired()
+	assert.True(t, cache.Has("template", template.Props{}))
+
+	<-time.After(10 * time.Millisecond)
+
+	assert.True(t, cache.Has("template", template.Props{})) // expired, but not cleared yet
+	cache.ClearExpired()
+	assert.False(t, cache.Has("template", template.Props{})) // cleared
+}

internal/http/handlers/error_page/handler.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"sync"
 	"sync/atomic"
 	"time"
 
@@ -15,7 +16,32 @@ import (
 )
 
 // New creates a new handler that returns an error page with the specified status code and format.
-func New(cfg *config.Config, log *logger.Logger) fasthttp.RequestHandler { //nolint:funlen,gocognit,gocyclo
+func New(cfg *config.Config, log *logger.Logger) (_ fasthttp.RequestHandler, closeCache func()) { //nolint:funlen,gocognit,gocyclo,lll
+	// if the ttl will be bigger than 1 second, the template functions like `nowUnix` will not work as expected
+	const cacheTtl = 900 * time.Millisecond // the cache TTL
+
+	var (
+		cache, stopCh = NewRenderedCache(cacheTtl), make(chan struct{})
+		stopOnce      sync.Once
+	)
+
+	// run a goroutine that will clear the cache from expired items. to stop the goroutine - close the stop channel
+	// or call the closeCache
+	go func() {
+		var timer = time.NewTimer(cacheTtl)
+		defer func() { timer.Stop(); cache.Clear() }()
+
+		for {
+			select {
+			case <-timer.C:
+				cache.ClearExpired()
+				timer.Reset(cacheTtl)
+			case <-stopCh:
+				return
+			}
+		}
+	}()
+
 	return func(ctx *fasthttp.RequestCtx) {
 		var (
 			reqHeaders = &ctx.Request.Header
@@ -106,57 +132,82 @@ func New(cfg *config.Config, log *logger.Logger) fasthttp.RequestHandler { //nol
 
 		switch {
 		case format == jsonFormat && cfg.Formats.JSON != "":
-			if content, err := template.Render(cfg.Formats.JSON, tplProps); err != nil {
-				j, _ := json.Marshal(fmt.Sprintf("Failed to render the JSON template: %s", err.Error()))
-				write(ctx, log, j)
-			} else {
-				write(ctx, log, content)
+			if cached, ok := cache.Get(cfg.Formats.JSON, tplProps); ok { // cache hit
+				write(ctx, log, cached)
+			} else { // cache miss
+				if content, err := template.Render(cfg.Formats.JSON, tplProps); err != nil {
+					errAsJson, _ := json.Marshal(fmt.Sprintf("Failed to render the JSON template: %s", err.Error()))
+					write(ctx, log, errAsJson) // error during rendering
+				} else {
+					cache.Put(cfg.Formats.JSON, tplProps, []byte(content))
+
+					write(ctx, log, content) // rendered successfully
+				}
 			}
 
 		case format == xmlFormat && cfg.Formats.XML != "":
-			if content, err := template.Render(cfg.Formats.XML, tplProps); err != nil {
-				write(ctx, log, fmt.Sprintf(
-					"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<error>Failed to render the XML template: %s</error>", err.Error(),
-				))
-			} else {
-				write(ctx, log, content)
+			if cached, ok := cache.Get(cfg.Formats.XML, tplProps); ok { // cache hit
+				write(ctx, log, cached)
+			} else { // cache miss
+				if content, err := template.Render(cfg.Formats.XML, tplProps); err != nil {
+					write(ctx, log, fmt.Sprintf(
+						"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<error>Failed to render the XML template: %s</error>\n", err.Error(),
+					))
+				} else {
+					cache.Put(cfg.Formats.XML, tplProps, []byte(content))
+
+					write(ctx, log, content)
+				}
 			}
 
 		case format == htmlFormat:
 			var templateName = templateToUse(cfg)
 
-			if tpl, found := cfg.Templates.Get(templateName); found {
-				if content, err := template.Render(tpl, tplProps); err != nil {
-					// TODO: add GZIP compression for the HTML content support
-					write(ctx, log, fmt.Sprintf(
-						"<!DOCTYPE html>\n<html><body>Failed to render the HTML template %s: %s</body></html>",
-						templateName,
-						err.Error(),
-					))
-				} else {
-					write(ctx, log, content)
+			if tpl, found := cfg.Templates.Get(templateName); found { //nolint:nestif
+				if cached, ok := cache.Get(tpl, tplProps); ok { // cache hit
+					write(ctx, log, cached)
+				} else { // cache miss
+					if content, err := template.Render(tpl, tplProps); err != nil {
+						// TODO: add GZIP compression for the HTML content support
+						write(ctx, log, fmt.Sprintf(
+							"<!DOCTYPE html>\n<html><body>Failed to render the HTML template %s: %s</body></html>\n",
+							templateName,
+							err.Error(),
+						))
+					} else {
+						cache.Put(tpl, tplProps, []byte(content))
+
+						write(ctx, log, content)
+					}
 				}
 			} else {
 				write(ctx, log, fmt.Sprintf(
-					"<!DOCTYPE html>\n<html><body>Template %s not found and cannot be used</body></html>", templateName,
+					"<!DOCTYPE html>\n<html><body>Template %s not found and cannot be used</body></html>\n", templateName,
 				))
 			}
 
 		default: // plainTextFormat as default
-			if cfg.Formats.PlainText != "" {
-				if content, err := template.Render(cfg.Formats.PlainText, tplProps); err != nil {
-					write(ctx, log, fmt.Sprintf("Failed to render the PlainText template: %s", err.Error()))
-				} else {
-					write(ctx, log, content)
+			if cfg.Formats.PlainText != "" { //nolint:nestif
+				if cached, ok := cache.Get(cfg.Formats.PlainText, tplProps); ok { // cache hit
+					write(ctx, log, cached)
+				} else { // cache miss
+					if content, err := template.Render(cfg.Formats.PlainText, tplProps); err != nil {
+						write(ctx, log, fmt.Sprintf("Failed to render the PlainText template: %s", err.Error()))
+					} else {
+						cache.Put(cfg.Formats.PlainText, tplProps, []byte(content))
+
+						write(ctx, log, content)
+					}
 				}
 			} else {
 				write(ctx, log, `The requested content format is not supported.
 Please create an issue on the project's GitHub page to request support for this format.
 
-Supported formats: JSON, XML, HTML, Plain Text`)
+Supported formats: JSON, XML, HTML, Plain Text
+`)
 			}
 		}
-	}
+	}, func() { stopOnce.Do(func() { close(stopCh) }) }
 }
 
 var (

internal/http/handlers/error_page/handler_test.go

@@ -159,7 +159,8 @@ func TestHandler(t *testing.T) {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 
-			var handler = error_page.New(tt.giveConfig(), logger.NewNop())
+			var handler, closeCache = error_page.New(tt.giveConfig(), logger.NewNop())
+			defer closeCache()
 
 			req, reqErr := http.NewRequest(http.MethodGet, tt.giveUrl, http.NoBody)
 			require.NoError(t, reqErr)
@@ -202,9 +203,11 @@ func TestRotationModeOnEachRequest(t *testing.T) {
 		lastResponseBody string
 		changedTimes     int
 
-		handler = error_page.New(&cfg, logger.NewNop())
+		handler, closeCache = error_page.New(&cfg, logger.NewNop())
 	)
 
+	defer func() { closeCache(); closeCache(); closeCache() }() // multiple calls should not panic
+
 	for range 300 {
 		req, reqErr := http.NewRequest(http.MethodGet, "http://testing/", http.NoBody)
 		require.NoError(t, reqErr)

internal/http/server.go

@@ -23,16 +23,16 @@ import (
 
 // Server is an HTTP server for serving error pages.
 type Server struct {
-	log    *logger.Logger
-	server *fasthttp.Server
+	log        *logger.Logger
+	server     *fasthttp.Server
+	beforeStop func()
 }
 
 // NewServer creates a new HTTP server.
-func NewServer(log *logger.Logger) Server {
+func NewServer(log *logger.Logger, readBufferSize uint) Server {
 	const (
-		readTimeout    = 30 * time.Second
-		writeTimeout   = readTimeout + 10*time.Second // should be bigger than the read timeout
-		maxHeaderBytes = (1 << 20) * 5                //nolint:mnd // 5 MB
+		readTimeout  = 30 * time.Second
+		writeTimeout = readTimeout + 10*time.Second // should be bigger than the read timeout
 	)
 
 	return Server{
@@ -40,33 +40,38 @@ func NewServer(log *logger.Logger) Server {
 		server: &fasthttp.Server{
 			ReadTimeout:                  readTimeout,
 			WriteTimeout:                 writeTimeout,
-			ReadBufferSize:               maxHeaderBytes,
+			ReadBufferSize:               int(readBufferSize),
 			DisablePreParseMultipartForm: true,
 			NoDefaultServerHeader:        true,
 			CloseOnShutdown:              true,
 			Logger:                       logger.NewStdLog(log),
 		},
+		beforeStop: func() {}, // noop
 	}
 }
 
 // Register server handlers, middlewares, etc.
-func (s *Server) Register(cfg *config.Config) error {
+func (s *Server) Register(cfg *config.Config) error { //nolint:funlen
 	var (
-		liveHandler       = live.New()
-		versionHandler    = version.New(appmeta.Version())
-		errorPagesHandler = ep.New(cfg, s.log)
-		faviconHandler    = static.New(static.Favicon)
+		liveHandler    = live.New()
+		versionHandler = version.New(appmeta.Version())
+		faviconHandler = static.New(static.Favicon)
+
+		errorPagesHandler, closeCache = ep.New(cfg, s.log)
 
 		notFound   = http.StatusText(http.StatusNotFound) + "\n"
 		notAllowed = http.StatusText(http.StatusMethodNotAllowed) + "\n"
 	)
 
+	// wrap the before shutdown function to close the cache
+	s.beforeStop = closeCache
+
 	s.server.Handler = func(ctx *fasthttp.RequestCtx) {
 		var url, method = string(ctx.Path()), string(ctx.Method())
 
 		switch {
 		// live endpoints
-		case url == "/health/live" || url == "/health" || url == "/healthz" || url == "/live":
+		case url == "/healthz" || url == "/health/live" || url == "/health" || url == "/live":
 			liveHandler(ctx)
 
 		// version endpoint
@@ -82,8 +87,9 @@ func (s *Server) Register(cfg *config.Config) error {
 		//	-	/{code}.html
 		//	- /{code}.htm
 		//	- /{code}
-		case method == fasthttp.MethodGet &&
-			(url == "/" || ep.URLContainsCode(url) || ep.HeadersContainCode(&ctx.Request.Header)):
+		//
+		// the HTTP method is not limited to GET and HEAD - it can be any
+		case url == "/" || ep.URLContainsCode(url) || ep.HeadersContainCode(&ctx.Request.Header):
 			errorPagesHandler(ctx)
 
 		// wrong requests handling
@@ -135,5 +141,7 @@ func (s *Server) Stop(timeout time.Duration) error {
 	var ctx, cancel = context.WithTimeout(context.Background(), timeout)
 	defer cancel()
 
+	s.beforeStop()
+
 	return s.server.ShutdownWithContext(ctx)
 }

internal/http/server_test.go

@@ -20,7 +20,7 @@ import (
 // TestRouting in fact is a test for the whole server, because it tests all the routes and their handlers.
 func TestRouting(t *testing.T) {
 	var (
-		srv = appHttp.NewServer(logger.NewNop())
+		srv = appHttp.NewServer(logger.NewNop(), 1025*5)
 		cfg = config.New()
 	)
 
@@ -38,7 +38,7 @@ func TestRouting(t *testing.T) {
 		Service Name: {{ service_name }}
 		Service Port: {{ service_port }}
 		Request ID: {{ request_id }}
-		Timestamp: {{ now.Unix }}
+		Timestamp: {{ nowUnix }}
 	</pre>{{ end }}
 </html>`))
 
@@ -221,6 +221,16 @@ func TestRouting(t *testing.T) {
 				assert.Contains(t, string(body), "404: Not Found")
 				assert.Contains(t, headers.Get("Content-Type"), "text/plain")
 			})
+
+			t.Run("other HTTP methods", func(t *testing.T) {
+				for _, method := range []string{http.MethodDelete, http.MethodPatch, http.MethodPost, http.MethodPut} {
+					var status, body, headers = sendRequest(t, method, baseUrl+"/404.html")
+
+					assert.Equal(t, http.StatusOK, status)
+					assert.Contains(t, string(body), "404: Not Found")
+					assert.Contains(t, headers.Get("Content-Type"), "text/plain")
+				}
+			})
 		})
 
 		t.Run("failure", func(t *testing.T) {
@@ -264,15 +274,6 @@ func TestRouting(t *testing.T) {
 				assert.Equal(t, http.StatusNotFound, status)
 				assertIsNotErrorPage(t, body)
 			})
-
-			t.Run("invalid HTTP methods", func(t *testing.T) {
-				for _, method := range []string{http.MethodDelete, http.MethodPatch, http.MethodPost, http.MethodPut} {
-					var status, body, _ = sendRequest(t, method, baseUrl+"/404.html")
-
-					assert.Equal(t, http.StatusMethodNotAllowed, status)
-					assertIsNotErrorPage(t, body)
-				}
-			})
 		})
 	})
 

internal/template/template.go

@@ -16,10 +16,9 @@ import (
 )
 
 var builtInFunctions = template.FuncMap{ //nolint:gochecknoglobals
-	// current time:
-	//	`{{ now.Unix }}`	// `1631610000`
-	//	`{{ now.Hour }}:{{ now.Minute }}:{{ now.Second }}`	// `15:4:5`
-	"now": time.Now,
+	// the current time in unix format (seconds since 1970 UTC):
+	//	`{{ nowUnix }}`	// `1631610000`
+	"nowUnix": func() int64 { return time.Now().Unix() },
 
 	// current hostname:
 	//	`{{ hostname }}`	// `localhost`

internal/template/template_test.go

@@ -27,7 +27,7 @@ func TestRender_BuiltInFunction(t *testing.T) {
 		wantErrMsg   string
 	}{
 		"now (unix)": {
-			giveTemplate: `{{ now.Unix }}`,
+			giveTemplate: `{{ nowUnix }}`,
 			wantResult:   strconv.Itoa(int(time.Now().Unix())),
 		},
 		"hostname":                  {giveTemplate: `{{ hostname }}`, wantResult: hostname},

templates/app-down.html

@@ -341,7 +341,7 @@
         <!-- {{- end }}{{ if request_id -}} -->
         <li><span data-l10n>Request ID</span>: <code>{{ request_id }}</code></li>
         <!-- {{- end -}} -->
-        <li><span data-l10n>Timestamp</span>: <code>{{ now.Unix }}</code></li>
+        <li><span data-l10n>Timestamp</span>: <code>{{ nowUnix }}</code></li>
       </ul>
     </div>
     <!-- {{- end -}} -->

templates/cats.html

@@ -150,7 +150,7 @@
   <!-- {{- end -}} -->
   <tr>
     <td class="name" data-l10n>Timestamp</td>
-    <td class="value">{{ now.Unix }}</td>
+    <td class="value">{{ nowUnix }}</td>
   </tr>
   </tbody>
 </table>

templates/connection.html

@@ -327,7 +327,7 @@
       <!-- {{- end }}{{ if request_id -}} -->
       <li><span data-l10n>Request ID</span>: <code>{{ request_id }}</code></li>
       <!-- {{- end -}} -->
-      <li><span data-l10n>Timestamp</span>: <code>{{ now.Unix }}</code></li>
+      <li><span data-l10n>Timestamp</span>: <code>{{ nowUnix }}</code></li>
     </ul>
   </div>
   <!-- {{- end -}} -->

templates/ghost.html

@@ -235,7 +235,7 @@
     <!-- {{- end -}} -->
     <tr>
       <td class="name" data-l10n>Timestamp</td>
-      <td class="value">{{ now.Unix }}</td>
+      <td class="value">{{ nowUnix }}</td>
     </tr>
     </tbody>
   </table>

templates/hacker-terminal.html

@@ -174,7 +174,7 @@
     <!-- {{- end }}{{ if request_id -}} -->
     <p class="output small"><span data-l10n>Request ID</span>: <code>{{ request_id }}</code></p>
     <!-- {{- end -}} -->
-    <p class="output small"><span data-l10n>Timestamp</span>: <code>{{ now.Unix }}</code></p>
+    <p class="output small"><span data-l10n>Timestamp</span>: <code>{{ nowUnix }}</code></p>
   </div>
   <!-- {{- end -}} -->
 </main>

templates/l7.html

@@ -157,7 +157,7 @@
         <!-- {{- end }}{{ if request_id -}} -->
         <li class="value">{{ request_id }}</li>
         <!-- {{- end -}} -->
-        <li class="value">{{ now.Unix }}</li>
+        <li class="value">{{ nowUnix }}</li>
       </ul>
       <!-- {{- end -}} -->
     </div>

templates/lost-in-space.html

@@ -442,7 +442,7 @@
       <!-- {{- end }}{{ if request_id -}} -->
       <li><span data-l10n>Request ID</span>: <code>{{ request_id }}</code></li>
       <!-- {{- end -}} -->
-      <li><span data-l10n>Timestamp</span>: <code>{{ now.Unix }}</code></li>
+      <li><span data-l10n>Timestamp</span>: <code>{{ nowUnix }}</code></li>
     </ul>
     <!-- {{- end -}} -->
   </div>

templates/noise.html

@@ -9,7 +9,7 @@
     {{ if service_name }}Service name: {{ service_name }}{{ end }}
     {{ if service_port }}Service port: {{ service_port }}{{ end }}
     {{ if request_id }}Request ID: {{ request_id }}{{ end }}
-    Timestamp: {{ now.Unix }}
+    Timestamp: {{ nowUnix }}
 {{ end }}
 -->
 <html lang="en">

templates/orient.html

@@ -253,7 +253,7 @@
           <!-- {{- end -}} -->
           <tr>
             <td class="name" data-l10n>Timestamp</td>
-            <td class="value">{{ now.Unix }}</td>
+            <td class="value">{{ nowUnix }}</td>
           </tr>
         </table>
       </div>

templates/shuffle.html

@@ -167,7 +167,7 @@
       <!-- {{- end -}} -->
       <tr>
         <td class="name"><span data-l10n>Timestamp</span>:</td>
-        <td class="value">{{ now.Unix }}</td>
+        <td class="value">{{ nowUnix }}</td>
       </tr>
     </table>
     <!-- {{- end -}} -->