add support for go-source meta tags

Go Packages inspects this to generate source links. Legacy GoDoc websites do too. There are perhaps other reasons a go-get redirector would want to include these. This change adds primitive support for them.
djmoch · Dec 9, 2023 · e29abc4 · e29abc4
1 parent 08f6126
commit e29abc4
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Showing 3 changed files with 54 additions and 31 deletions.
diff --git a/cmd/shrt/internal/base/base.go b/cmd/shrt/internal/base/base.go
@@ -11,13 +11,15 @@ import (
 
 // Environment variable keys
 const (
-	SHRTENV      = "SHRTENV"
-	SHRT_SRVNAME = "SHRT_SRVNAME"
-	SHRT_SCMTYPE = "SHRT_SCMTYPE"
-	SHRT_SUFFIX  = "SHRT_SUFFIX"
-	SHRT_RDRNAME = "SHRT_RDRNAME"
-	SHRT_BARERDR = "SHRT_BARERDR"
-	SHRT_DBPATH  = "SHRT_DBPATH"
+	SHRTENV           = "SHRTENV"
+	SHRT_SRVNAME      = "SHRT_SRVNAME"
+	SHRT_SCMTYPE      = "SHRT_SCMTYPE"
+	SHRT_SUFFIX       = "SHRT_SUFFIX"
+	SHRT_RDRNAME      = "SHRT_RDRNAME"
+	SHRT_BARERDR      = "SHRT_BARERDR"
+	SHRT_DBPATH       = "SHRT_DBPATH"
+	SHRT_GOSOURCEDIR  = "SHRT_GOSOURCEDIR"
+	SHRT_GOSOURCEFILE = "SHRT_GOSOURCEFILE"
 )
 
 // KnownEnv is a list of environment variables that affect the
@@ -30,6 +32,8 @@ const KnownEnv = `
 	SHRT_RDRNAME
 	SHRT_BARERDR
 	SHRT_DBPATH
+	SHRT_GOSOURCEDIR
+	SHRT_GOSOURCEFILE
 	`
 
 type Command struct {

diff --git a/cmd/shrt/internal/env/env.go b/cmd/shrt/internal/env/env.go
@@ -21,11 +21,13 @@ import (
 )
 
 const (
-	srvNameDefault = "example.com"
-	scmTypeDefault = "git"
-	suffixDefault  = ".git"
-	rdrNameDefault = "github.com/user"
-	bareRdrDefault = "example.org"
+	srvNameDefault      = "example.com"
+	scmTypeDefault      = "git"
+	suffixDefault       = ".git"
+	rdrNameDefault      = "github.com/user"
+	bareRdrDefault      = "example.org"
+	goSourceDirDefault  = ""
+	goSourceFileDefault = ""
 )
 
 var Cmd = &base.Command{
@@ -187,7 +189,9 @@ func ConfigFromEnv() shrt.Config {
 		RdrName: envOrDefault(base.SHRT_RDRNAME, rdrNameDefault),
 		BareRdr: envOrDefault(base.SHRT_BARERDR, bareRdrDefault),
 		// Trim the leading / to satisfy fs.FS
-		DbPath: strings.TrimPrefix(envOrDefault(base.SHRT_DBPATH, dbPathDefault), "/"),
+		DbPath:       strings.TrimPrefix(envOrDefault(base.SHRT_DBPATH, dbPathDefault), "/"),
+		GoSourceDir:  envOrDefault(base.SHRT_GOSOURCEDIR, goSourceDirDefault),
+		GoSourceFile: envOrDefault(base.SHRT_GOSOURCEFILE, goSourceFileDefault),
 	}
 }
 
@@ -224,13 +228,15 @@ func MergeEnv() {
 	}
 
 	defaults := map[string]string{
-		base.SHRTENV:      envDefault,
-		base.SHRT_SRVNAME: srvNameDefault,
-		base.SHRT_SCMTYPE: scmTypeDefault,
-		base.SHRT_SUFFIX:  suffixDefault,
-		base.SHRT_RDRNAME: rdrNameDefault,
-		base.SHRT_BARERDR: bareRdrDefault,
-		base.SHRT_DBPATH:  dbPathDefault,
+		base.SHRTENV:           envDefault,
+		base.SHRT_SRVNAME:      srvNameDefault,
+		base.SHRT_SCMTYPE:      scmTypeDefault,
+		base.SHRT_SUFFIX:       suffixDefault,
+		base.SHRT_RDRNAME:      rdrNameDefault,
+		base.SHRT_BARERDR:      bareRdrDefault,
+		base.SHRT_DBPATH:       dbPathDefault,
+		base.SHRT_GOSOURCEDIR:  goSourceDirDefault,
+		base.SHRT_GOSOURCEFILE: goSourceFileDefault,
 	}
 
 	// Populate missing environment variables with defaults

diff --git a/shrt.go b/shrt.go
@@ -33,7 +33,8 @@ var shrtrsp = `<!DOCTYPE html>
 <html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>"
-<meta name="go-import" content="{{ .SrvName }}/{{ .Repo }} {{ .ScmType }} {{ .URL }}">
+<meta name="go-import" content="{{ .SrvName }}/{{ .Repo }} {{ .ScmType }} {{ .URL }}">{{ if ne .GoSourceDir "" }}
+<meta name="go-source" content="{{ .SrvName }}/{{ .Repo }} {{ .URL }} {{ .URL }}/{{ .GoSourceDir }} {{ .URL }}/{{ .GoSourceFile }}">{{ end }}
 <meta http-equiv="refresh" content="0; url=https://godoc.org/{{ .SrvName }}/{{ .DocPath }}">
 </head>
 <body>
@@ -43,11 +44,13 @@ Redirecting to docs at <a href="https://godoc.org/{{ .SrvName }}/{{ .DocPath }}"
 `
 
 type shrtRequest struct {
-	SrvName string
-	Repo    string
-	ScmType string
-	URL     string
-	DocPath string
+	SrvName      string
+	Repo         string
+	ScmType      string
+	URL          string
+	DocPath      string
+	GoSourceDir  string
+	GoSourceFile string
 }
 
 // Config contains all of the global configuration for Shrt. All
@@ -66,6 +69,14 @@ type Config struct {
 	BareRdr string
 	// The path to the [ShrtFile]-formatted database file.
 	DbPath string
+	// The string to append to the URL for go-get redirects to
+	// form the directory entry in the go-source meta tag. This
+	// key is experimental and may be removed in a future release.
+	GoSourceDir string
+	// The string to append to the URL for go-get redirects to
+	// form the file entry in the go-source meta tag.  This
+	// key is experimental and may be removed in a future release.
+	GoSourceFile string
 }
 
 // ShrtHandler is the core [http.Handler] for go-shrt.
@@ -124,11 +135,13 @@ func (s *ShrtHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		log.Println("go-get request for", key)
 		t := template.Must(template.New("shrt").Parse(shrtrsp))
 		sReq := shrtRequest{
-			SrvName: s.Config.SrvName,
-			Repo:    key,
-			ScmType: s.Config.ScmType,
-			URL:     val.URL,
-			DocPath: p,
+			SrvName:      s.Config.SrvName,
+			Repo:         key,
+			ScmType:      s.Config.ScmType,
+			URL:          val.URL,
+			DocPath:      p,
+			GoSourceDir:  s.Config.GoSourceDir,
+			GoSourceFile: s.Config.GoSourceFile,
 		}
 		if err := t.Execute(w, sReq); err != nil {
 			log.Println("error executing template:", err)