feat: Add HTML/CSS/JS minification on the fly (#293)

Dockerfile

@@ -32,7 +32,10 @@ FROM develop AS compile
 # can be passed with any prefix (like `v1.2.3@GITHASH`), e.g.: `docker build --build-arg "APP_VERSION=v1.2.3" .`
 ARG APP_VERSION="undefined@docker"
 
-RUN --mount=type=bind,source=.,target=/src set -x \
+# copy the source code
+COPY . /src
+
+RUN set -x \
     && go generate ./... \
     && CGO_ENABLED=0 LDFLAGS="-s -w -X gh.tarampamp.am/error-pages/internal/appmeta.version=${APP_VERSION}" \
       go build -trimpath -ldflags "${LDFLAGS}" -o /tmp/error-pages ./cmd/error-pages/ \

README.md

@@ -610,11 +610,11 @@ Test completed successfully. Here is the output:
 Running 15s test @ http://127.0.0.1:8080/
   12 threads and 400 connections
   Thread Stats   Avg      Stdev     Max   +/- Stdev
-    Latency     3.54ms    4.90ms  74.57ms   86.55%
+    Latency     4.52ms    6.43ms  94.34ms   85.44%
-    Req/Sec    16.47k     2.89k   38.11k    69.46%
+    Req/Sec    15.76k     2.83k   29.64k    69.20%
-  2967567 requests in 15.09s, 44.70GB read
+  2839632 requests in 15.09s, 32.90GB read
-Requests/sec: 196596.49
+Requests/sec: 188185.61
-Transfer/sec:      2.96GB
+Transfer/sec:      2.18GB
 
 Starting the test to bomb DIFFERENT PAGES (codes). Please, be patient...
 Test completed successfully. Here is the output:
@@ -622,11 +622,11 @@ Test completed successfully. Here is the output:
 Running 15s test @ http://127.0.0.1:8080/
   12 threads and 400 connections
   Thread Stats   Avg      Stdev     Max   +/- Stdev
-    Latency     4.25ms    6.03ms  74.23ms   86.97%
+    Latency     6.75ms   13.71ms 252.66ms   91.94%
-    Req/Sec    14.29k     2.75k   32.16k    69.63%
+    Req/Sec    14.06k     3.25k   26.39k    71.98%
-  2563245 requests in 15.07s, 38.47GB read
+  2534473 requests in 15.10s, 29.22GB read
-Requests/sec: 170062.69
+Requests/sec: 167899.78
-Transfer/sec:      2.55GB
+Transfer/sec:      1.94GB
 ```
 
 </details>
@@ -678,6 +678,7 @@ The following flags are supported:
 | `--proxy-headers="…"`        | HTTP headers listed here will be proxied from the original request to the error page response (comma-separated list)                                                                                                                                                                                                      | `X-Request-Id,X-Trace-Id,X-Amzn-Trace-Id` |    `PROXY_HTTP_HEADERS`     |
 | `--rotation-mode="…"`        | Templates automatic rotation mode (disabled/random-on-startup/random-on-each-request/random-hourly/random-daily)                                                                                                                                                                                                          |                `disabled`                 |  `TEMPLATES_ROTATION_MODE`  |
 | `--read-buffer-size="…"`     | 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)                                      |                  `5120`                   |     `READ_BUFFER_SIZE`      |
+| `--disable-minification`     | Disable the minification of HTML pages, including CSS, SVG, and JS (may be useful for debugging)                                                                                                                                                                                                                          |                  `false`                  |   `DISABLE_MINIFICATION`    |
 
 ### `build` command (aliases: `b`)
 
@@ -691,14 +692,15 @@ $ error-pages [GLOBAL FLAGS] build [COMMAND FLAGS] [ARGUMENTS...]
 
 The following flags are supported:
 
-| Name                                        | Description                                                                                                                                                                                                                                                                                                               | Default value | Environment variables |
+| Name                                        | Description                                                                                                                                                                                                                                                                                                               | Default value |  Environment variables |
-|---------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-------------:|:---------------------:|
+|---------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:-------------:|:----------------------:|
-| `--add-template="…"`                        | 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)                                                                                                                                                                                |     `[]`      |        *none*         |
+| `--add-template="…"`                        | 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)                                                                                                                                                                                |     `[]`      |         *none*         |
-| `--disable-template="…"`                    | Disable the specified template by its name (useful to disable the built-in templates and use only custom ones)                                                                                                                                                                                                            |     `[]`      |        *none*         |
+| `--disable-template="…"`                    | Disable the specified template by its name (useful to disable the built-in templates and use only custom ones)                                                                                                                                                                                                            |     `[]`      |         *none*         |
-| `--add-code="…"`                            | 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) |    `map[]`    |        *none*         |
+| `--add-code="…"`                            | 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) |    `map[]`    |         *none*         |
-| `--disable-l10n`                            | Disable localization of error pages (if the template supports localization)                                                                                                                                                                                                                                               |    `false`    |    `DISABLE_L10N`     |
+| `--disable-l10n`                            | Disable localization of error pages (if the template supports localization)                                                                                                                                                                                                                                               |    `false`    |     `DISABLE_L10N`     |
-| `--index` (`-i`)                            | Generate index.html file with links to all error pages                                                                                                                                                                                                                                                                    |    `false`    |        *none*         |
+| `--index` (`-i`)                            | Generate index.html file with links to all error pages                                                                                                                                                                                                                                                                    |    `false`    |         *none*         |
-| `--target-dir="…"` (`--out`, `--dir`, `-o`) | Directory to put the built error pages into                                                                                                                                                                                                                                                                               |      `.`      |        *none*         |
+| `--target-dir="…"` (`--out`, `--dir`, `-o`) | Directory to put the built error pages into                                                                                                                                                                                                                                                                               |      `.`      |         *none*         |
+| `--disable-minification`                    | Disable the minification of HTML pages, including CSS, SVG, and JS (may be useful for debugging)                                                                                                                                                                                                                          |    `false`    | `DISABLE_MINIFICATION` |
 
 ### `healthcheck` command (aliases: `chk`, `health`, `check`)
 

go.mod

@@ -4,6 +4,7 @@ go 1.22
 
 require (
 	github.com/stretchr/testify v1.9.0
+	github.com/tdewolff/minify/v2 v2.20.35
 	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
@@ -19,6 +20,7 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.12.0 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/tdewolff/parse/v2 v2.7.15 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect

go.sum

@@ -26,6 +26,13 @@ github.com/russross/blackfriday/v2 v2.1.0 h1:JIOH55/0cWyOuilr9/qlrm0BSXldqnqwMsf
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/tdewolff/minify/v2 v2.20.35 h1:/Vq/oivpkFyi2PViD25XHZZbJz+eO4OmPSgePex1kBU=
+github.com/tdewolff/minify/v2 v2.20.35/go.mod h1:L1VYef/jwKw6Wwyk5A+T0mBjjn3mMPgmjjA688RNsxU=
+github.com/tdewolff/parse/v2 v2.7.15 h1:hysDXtdGZIRF5UZXwpfn3ZWRbm+ru4l53/ajBRGpCTw=
+github.com/tdewolff/parse/v2 v2.7.15/go.mod h1:3FbJWZp3XT9OWVN3Hmfp0p/a08v4h8J9W1aghka0soA=
+github.com/tdewolff/test v1.0.11-0.20231101010635-f1265d231d52/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
+github.com/tdewolff/test v1.0.11-0.20240106005702-7de5f7df4739 h1:IkjBCtQOOjIn03u/dMQK9g+Iw9ewps4mCl1nB8Sscbo=
+github.com/tdewolff/test v1.0.11-0.20240106005702-7de5f7df4739/go.mod h1:XPuWBzvdUzhCuxWO1ojpXsyzsA5bFoS3tO/Q3kFuTG8=
 github.com/urfave/cli-docs/v3 v3.0.0-alpha5 h1:H1oWnR2/GN0dNm2PVylws+GxSOD6YOwW/jI5l78YfPk=
 github.com/urfave/cli-docs/v3 v3.0.0-alpha5/go.mod h1:AIqom6Q60U4tiqHp41i7+/AB2XHgi1WvQ7jOFlccmZ4=
 github.com/urfave/cli/v3 v3.0.0-alpha9 h1:P0RMy5fQm1AslQS+XCmy9UknDXctOmG/q/FZkUFnJSo=

internal/cli/app.go

@@ -6,7 +6,6 @@ import (
 	"runtime"
 	"strings"
 
-	_ "github.com/urfave/cli-docs/v3" // required for `go generate` to work
 	"github.com/urfave/cli/v3"
 
 	"gh.tarampamp.am/error-pages/internal/appmeta"
@@ -17,7 +16,7 @@ import (
 	"gh.tarampamp.am/error-pages/internal/logger"
 )
 
-//go:generate go run update_readme.go
+//go:generate go run app_generate.go
 
 // NewApp creates a new console application.
 func NewApp(appName string) *cli.Command { //nolint:funlen

internal/cli/app_generate.go

@@ -1,5 +1,4 @@
-//go:build ignore
+//go:build generate
-// +build ignore
 
 package main
 
@@ -17,8 +16,10 @@ func main() {
 	if stat, err := os.Stat(readmePath); err == nil && stat.Mode().IsRegular() {
 		if err = cliDocs.ToTabularToFileBetweenTags(cli.NewApp(""), "error-pages", readmePath); err != nil {
 			panic(err)
+		} else {
+			println("✔ cli docs updated successfully")
 		}
 	} else if err != nil {
-		println("readme file not found, cli docs not updated:", err.Error())
+		println("⚠ readme file not found, cli docs not updated:", err.Error())
 	}
 }

internal/cli/build/command.go

@@ -39,11 +39,12 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 		cmd command
 		cfg = config.New()
 
-		addTplFlag      = shared.AddTemplatesFlag
+		addTplFlag              = shared.AddTemplatesFlag
-		disableTplFlag  = shared.DisableTemplateNamesFlag
+		disableTplFlag          = shared.DisableTemplateNamesFlag
-		addCodeFlag     = shared.AddHTTPCodesFlag
+		addCodeFlag             = shared.AddHTTPCodesFlag
-		disableL10nFlag = shared.DisableL10nFlag
+		disableL10nFlag         = shared.DisableL10nFlag
-		createIndexFlag = cli.BoolFlag{
+		disableMinificationFlag = shared.DisableMinificationFlag
+		createIndexFlag         = cli.BoolFlag{
 			Name:     "index",
 			Aliases:  []string{"i"},
 			Usage:    "Generate index.html file with links to all error pages",
@@ -81,6 +82,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 		Usage:   "Build the static error pages and put them into a specified directory",
 		Action: func(ctx context.Context, c *cli.Command) error {
 			cfg.L10n.Disable = c.Bool(disableL10nFlag.Name)
+			cfg.DisableMinification = c.Bool(disableMinificationFlag.Name)
 			cmd.opt.createIndex = c.Bool(createIndexFlag.Name)
 			cmd.opt.targetDirAbsPath, _ = filepath.Abs(c.String(targetDirFlag.Name)) // an error checked by [os.Stat] validator
 
@@ -140,13 +142,14 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit
 			&disableL10nFlag,
 			&createIndexFlag,
 			&targetDirFlag,
+			&disableMinificationFlag,
 		},
 	}
 
 	return cmd.c
 }
 
-func (cmd *command) Run( //nolint:funlen
+func (cmd *command) Run( //nolint:funlen,gocognit
 	ctx context.Context,
 	log *logger.Logger,
 	cfg *config.Config,
@@ -172,13 +175,21 @@ func (cmd *command) Run( //nolint:funlen
 
 			var outFilePath = path.Join(cmd.opt.targetDirAbsPath, templateName, code+".html")
 
-			if content, renderErr := appTemplate.Render(templateContent, appTemplate.Props{
+			if content, renderErr := appTemplate.Render(templateContent, appTemplate.Props{ //nolint:nestif
 				Code:               uint16(codeAsUint),
 				Message:            codeDescription.Message,
 				Description:        codeDescription.Description,
 				L10nDisabled:       cfg.L10n.Disable,
 				ShowRequestDetails: false,
 			}); renderErr == nil {
+				if !cfg.DisableMinification {
+					if mini, minErr := appTemplate.MiniHTML(content); minErr != nil {
+						log.Warn("Cannot minify the content", logger.Error(minErr))
+					} else {
+						content = mini
+					}
+				}
+
 				if err := os.WriteFile(outFilePath, []byte(content), os.FileMode(0664)); err != nil { //nolint:mnd
 					return err
 				}

internal/cli/serve/command.go

@@ -38,13 +38,14 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 	)
 
 	var (
-		addrFlag        = shared.ListenAddrFlag
+		addrFlag                = shared.ListenAddrFlag
-		portFlag        = shared.ListenPortFlag
+		portFlag                = shared.ListenPortFlag
-		addTplFlag      = shared.AddTemplatesFlag
+		addTplFlag              = shared.AddTemplatesFlag
-		disableTplFlag  = shared.DisableTemplateNamesFlag
+		disableTplFlag          = shared.DisableTemplateNamesFlag
-		addCodeFlag     = shared.AddHTTPCodesFlag
+		addCodeFlag             = shared.AddHTTPCodesFlag
-		disableL10nFlag = shared.DisableL10nFlag
+		disableL10nFlag         = shared.DisableL10nFlag
-		jsonFormatFlag  = cli.StringFlag{
+		disableMinificationFlag = shared.DisableMinificationFlag
+		jsonFormatFlag          = cli.StringFlag{
 			Name: "json-format",
 			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)",
@@ -182,6 +183,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 			cfg.RespondWithSameHTTPCode = c.Bool(sendSameHTTPCodeFlag.Name)
 			cfg.RotationMode, _ = config.ParseRotationMode(c.String(rotationModeFlag.Name))
 			cfg.ShowDetails = c.Bool(showDetailsFlag.Name)
+			cfg.DisableMinification = c.Bool(disableMinificationFlag.Name)
 
 			{ // override default JSON, XML, and PlainText formats
 				if c.IsSet(jsonFormatFlag.Name) {
@@ -303,6 +305,7 @@ func NewCommand(log *logger.Logger) *cli.Command { //nolint:funlen,gocognit,gocy
 			&proxyHeadersListFlag,
 			&rotationModeFlag,
 			&readBufferSizeFlag,
+			&disableMinificationFlag,
 		},
 	}
 

internal/cli/shared/flags.go

@@ -146,3 +146,11 @@ var DisableL10nFlag = cli.BoolFlag{
 	Category: CategoryOther,
 	OnlyOnce: true,
 }
+
+var DisableMinificationFlag = cli.BoolFlag{
+	Name:     "disable-minification",
+	Usage:    "Disable the minification of HTML pages, including CSS, SVG, and JS (may be useful for debugging)",
+	Sources:  cli.EnvVars("DISABLE_MINIFICATION"),
+	Category: CategoryOther,
+	OnlyOnce: true,
+}

internal/cli/shared/flags_test.go

@@ -216,3 +216,12 @@ func TestDisableL10nFlag(t *testing.T) {
 	assert.Equal(t, "disable-l10n", flag.Name)
 	assert.Contains(t, flag.Sources.String(), "DISABLE_L10N")
 }
+
+func TestDisableMinificationFlag(t *testing.T) {
+	t.Parallel()
+
+	var flag = shared.DisableMinificationFlag
+
+	assert.Equal(t, "disable-minification", flag.Name)
+	assert.Contains(t, flag.Sources.String(), "DISABLE_MINIFICATION")
+}

internal/config/config.go

@@ -56,6 +56,9 @@ type Config struct {
 	// ShowDetails determines whether to show additional details in the error response, extracted from the
 	// incoming request (if supported by the template).
 	ShowDetails bool
+
+	// DisableMinification determines whether to disable minification of the rendered content (e.g., HTML, CSS) or not.
+	DisableMinification bool
 }
 
 const defaultJSONFormat string = `{

internal/config/config_test.go

@@ -24,6 +24,7 @@ func TestNew(t *testing.T) {
 		assert.NotEmpty(t, cfg.TemplateName)
 		assert.True(t, cfg.Templates.Has(cfg.TemplateName))
 		assert.Equal(t, uint16(http.StatusNotFound), cfg.DefaultCodeToRender)
+		assert.False(t, cfg.DisableMinification)
 	})
 
 	t.Run("changing cfg1 should not affect cfg2", func(t *testing.T) {

internal/http/handlers/error_page/handler.go

@@ -175,6 +175,14 @@ func New(cfg *config.Config, log *logger.Logger) (_ fasthttp.RequestHandler, clo
 							err.Error(),
 						))
 					} else {
+						if !cfg.DisableMinification {
+							if mini, minErr := template.MiniHTML(content); minErr != nil {
+								log.Warn("HTML minification failed", logger.Error(minErr))
+							} else {
+								content = mini
+							}
+						}
+
 						cache.Put(tpl, tplProps, []byte(content))
 
 						write(ctx, log, content)

internal/http/handlers/error_page/handler_test.go

@@ -48,7 +48,7 @@ func TestHandler(t *testing.T) {
 			wantStatusCode: http.StatusOK,
 			wantHeaders:    map[string]string{"Content-Type": "text/html; charset=utf-8"},
 			wantBodyIncludes: []string{
-				"<!DOCTYPE html>",
+				"<!doctype html>",
 				"<title>407: Proxy Authentication Required",
 				"Proxy Authentication Required",
 			},

internal/template/minify.go

@@ -0,0 +1,23 @@
+package template
+
+import (
+	"github.com/tdewolff/minify/v2"
+	"github.com/tdewolff/minify/v2/css"
+	"github.com/tdewolff/minify/v2/html"
+	"github.com/tdewolff/minify/v2/js"
+	"github.com/tdewolff/minify/v2/svg"
+)
+
+var htmlMinify = func() *minify.M { //nolint:gochecknoglobals
+	var m = minify.New()
+
+	m.AddFunc("text/css", css.Minify)
+	m.Add("text/html", &html.Minifier{KeepDocumentTags: true, KeepEndTags: true, KeepQuotes: true})
+	m.AddFunc("image/svg+xml", svg.Minify)
+	m.AddFunc("application/javascript", js.Minify)
+
+	return m
+}()
+
+// MiniHTML minifies HTML data, including inline CSS, SVG and JS.
+func MiniHTML(data string) (string, error) { return htmlMinify.String("text/html", data) }

internal/template/minify_test.go

@@ -0,0 +1,94 @@
+package template_test
+
+import (
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"gh.tarampamp.am/error-pages/internal/template"
+)
+
+func TestMiniHTML(t *testing.T) {
+	t.Parallel()
+
+	var wg sync.WaitGroup
+
+	for range 100 { // race condition provocation
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+
+			for give, want := range map[string]string{
+				"": "",
+				`<!-- Simple HTML page -->
+<!DOCTYPE html>
+<html>
+<head>
+	<title>Test</title>
+</head>
+<body>
+	<h1 align="center">Test</h1>
+</body>
+</html>`: `<!doctype html><html><head><title>Test</title></head><body><h1 align="center">Test</h1></body></html>`,
+				`<!-- css styles -->
+<html>
+<head>
+	<style>
+		.foo:hover {
+			color: #f0a; /* comment */
+		}
+	</style>
+</head>
+<body>
+	<p style="color: red" class="bar">Text</p>
+</body>
+</html>`: `<html><head><style>.foo:hover{color:#f0a}</style></head><body><p style="color:red" class="bar">Text</p></body></html>`,
+				`<!-- svg -->
+<svg xmlns="http://www.w3.org/2000/svg">
+	<g>
+		<circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
+	</g>
+</svg>`: `<svg><g><circle cx="50" cy="50" r="40" stroke="#000" stroke-width="3" fill="red"/></g></svg>`,
+				`<!-- js -->
+<html>
+<body>
+<script>
+	// comment
+	console.log('Hello, World!');
+
+	let foo = 1;
+	foo++;
+</script>
+</body>
+</html>`: `<html><body><script>console.log("Hello, World!");let foo=1;foo++</script></body></html>`,
+				`<!-- js module not changed -->
+<html>
+<body>
+<script type="module">
+	// comment
+	console.log('Hello, World!');
+
+	let foo = 1;
+	foo++;
+</script>
+</body>
+</html>`: `<html><body><script type="module">
+	// comment
+	console.log('Hello, World!');
+
+	let foo = 1;
+	foo++;
+</script></body></html>`,
+			} {
+				var got, err = template.MiniHTML(give)
+
+				assert.NoError(t, err)
+				assert.Equal(t, want, got)
+			}
+		}()
+	}
+
+	wg.Wait()
+}