Minify html on-the-fly before sending it to users

go.mod

@@ -15,7 +15,9 @@ require (
 	github.com/gorilla/websocket v1.5.0
 	github.com/julienschmidt/httprouter v1.3.0
 	github.com/pkg/errors v0.9.1
+	github.com/pquerna/otp v1.4.0
 	github.com/rs/zerolog v1.28.0
+	github.com/tdewolff/minify v2.3.6+incompatible
 	github.com/tkw1536/goprogram v0.2.4
 	golang.org/x/crypto v0.3.0
 	golang.org/x/exp v0.0.0-20221205204356-47842c84f3db
@@ -35,7 +37,8 @@ require (
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.16 // indirect
-	github.com/pquerna/otp v1.4.0 // indirect
+	github.com/tdewolff/parse v2.3.4+incompatible // indirect
+	github.com/tdewolff/test v1.0.7 // indirect
 	golang.org/x/sys v0.3.0 // indirect
 	golang.org/x/tools v0.4.0 // indirect
 )

go.sum

@@ -9,6 +9,7 @@ github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be/go.mod h1:ySMOLuW
 github.com/boombuler/barcode v1.0.1-0.20190219062509-6c824513bacc h1:biVzkmvwrH8WK8raXaxBx6fRVTlJILwEwQGL1I/ByEI=
 github.com/boombuler/barcode v1.0.1-0.20190219062509-6c824513bacc/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl3JlRe0mD8=
 github.com/coreos/go-systemd/v22 v22.3.3-0.20220203105225-a9a7ef127534/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/feiin/sqlstring v0.3.0 h1:iyPEFijI2BxpY2M+AuhIvdNManzXa2OwGzuPaEMLUgo=
 github.com/feiin/sqlstring v0.3.0/go.mod h1:xpZTjVUw1nD3hMgF9SMRdPiooKSikLf4PS5j2NTn3RI=
@@ -46,6 +47,7 @@ github.com/mattn/go-isatty v0.0.16 h1:bq3VjFmv/sOjHtdEhmkEV4x1AJtvUvOJ2PFAZ5+peK
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pquerna/otp v1.4.0 h1:wZvl1TIVxKRThZIBiwOOHOGP/1+nZyWBil9Y2XNEDzg=
 github.com/pquerna/otp v1.4.0/go.mod h1:dkJfzwRKNiegxyNb54X/3fLwhCynbMspSyWKnvi1AEg=
@@ -53,7 +55,14 @@ github.com/rs/xid v1.4.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
 github.com/rs/zerolog v1.28.0 h1:MirSo27VyNi7RJYP3078AA1+Cyzd2GB66qy3aUHvsWY=
 github.com/rs/zerolog v1.28.0/go.mod h1:NILgTygv/Uej1ra5XxGf82ZFSLk58MFGAUS2o6usyD0=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/tdewolff/minify v2.3.6+incompatible h1:2hw5/9ZvxhWLvBUnHE06gElGYz+Jv9R4Eys0XUzItYo=
+github.com/tdewolff/minify v2.3.6+incompatible/go.mod h1:9Ov578KJUmAWpS6NeZwRZyT56Uf6o3Mcz9CEsg8USYs=
+github.com/tdewolff/parse v2.3.4+incompatible h1:x05/cnGwIMf4ceLuDMBOdQ1qGniMoxpP46ghf0Qzh38=
+github.com/tdewolff/parse v2.3.4+incompatible/go.mod h1:8oBwCsVmUkgHO8M5iCzSIDtpzXOT0WXX9cWhz+bIzJQ=
+github.com/tdewolff/test v1.0.7 h1:8Vs0142DmPFW/bQeHRP3MV19m1gvndjUb1sn8yy74LM=
+github.com/tdewolff/test v1.0.7/go.mod h1:6DAvZliBAAnD7rhVgwaM7DE5/d9NMOAJ09SqYqeK4QE=
 github.com/tkw1536/goprogram v0.2.4 h1:1l3+j8xjY3E3uf+ba3QRGWm09ucFCKrnNLq6g1Gq8YA=
 github.com/tkw1536/goprogram v0.2.4/go.mod h1:3Ngcwy7jtsZ+pINc+JfLdf8TWbvthdSS2T6Vbg44Fy8=
 golang.org/x/crypto v0.0.0-20220826181053-bd7e27e6170d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=

internal/dis/component/control/home/cron.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/dis/component"
+	"github.com/FAU-CDI/wisski-distillery/pkg/httpx"
 )
 
 type UpdateInstanceList struct {
@@ -77,6 +78,6 @@ func (ur *UpdateHome) Cron(ctx context.Context) error {
 		return err
 	}
 
-	ur.Dependencies.Home.homeBytes.Set(bytes)
+	ur.Dependencies.Home.homeBytes.Set(httpx.MinifyHTML(bytes))
 	return nil
 }

pkg/httpx/errors.go

@@ -72,6 +72,6 @@ var (
 		return json.Marshal(map[string]any{"status": text, "code": code})
 	})
 	HTMLInterceptor = StatusInterceptor("text/html", func(code int, text string) ([]byte, error) {
-		return []byte(`<!DOCTYPE HTML><title>` + text + `</title>` + text), nil
+		return MinifyHTML([]byte(`<!DOCTYPE HTML><title>` + text + `</title>` + text)), nil
 	})
 )

pkg/httpx/html.go

@@ -17,10 +17,15 @@ func WriteHTML[T any](result T, err error, template *template.Template, template
 	w.Header().Set("Content-Type", "text/html")
 	w.WriteHeader(http.StatusOK)
 
+	// minify html!
+	minifier := MinifyHTMLWriter(w)
+	defer minifier.Close()
+
+	// and return the template
 	if templateName != "" {
-		template.ExecuteTemplate(w, templateName, result)
+		template.ExecuteTemplate(minifier, templateName, result)
 	} else {
-		template.Execute(w, result)
+		template.Execute(minifier, result)
 	}
 }
 

pkg/httpx/html_minify.go

@@ -0,0 +1,42 @@
+package httpx
+
+import (
+	"io"
+	"regexp"
+
+	"github.com/tdewolff/minify"
+	"github.com/tdewolff/minify/css"
+	"github.com/tdewolff/minify/html"
+	"github.com/tdewolff/minify/js"
+	"github.com/tdewolff/minify/svg"
+)
+
+// minifier holds the minfier used for all html minification
+//
+// NOTE(twiesing): We can't use an init function for this, because otherwise initialization order is incorrect.
+var minifier = (func() *minify.M {
+	m := minify.New()
+	m.AddFunc("text/html", html.Minify)
+	m.AddFunc("text/css", css.Minify)
+	m.AddFunc("image/svg+xml", svg.Minify)
+	m.AddFuncRegexp(regexp.MustCompile("^(application|text)/(x-)?(java|ecma)script$"), js.Minify)
+	return m
+})()
+
+// MinifyHTMLWriter wraps the given io.Writer to minify the given html instead.
+// The writer must be closed explicitly.
+//
+// Specific environments may chose to disable http minification, in which case MinifyHTMLWriter becomes the identity function.
+func MinifyHTMLWriter(dest io.Writer) io.WriteCloser {
+	return minifier.Writer("text/html", dest)
+}
+
+// MinifyHTML minifies the html source.
+// If an error occurs, returns the unmodified source instead.
+func MinifyHTML(source []byte) []byte {
+	result, err := minifier.Bytes("text/html", source)
+	if err != nil {
+		return source
+	}
+	return result
+}

pkg/lazy/lazy.go

@@ -5,7 +5,7 @@ import (
 )
 
 // Lazy holds a lazily initialized value of T.
-// Lazy non-zero lazy must not be copied after first use.
+// A non-zero lazy must not be copied after first use.
 type Lazy[T any] struct {
 	once sync.Once