httpcaddyfile: Add 'vars' directive

See discussion in #4650

caddyconfig/httpcaddyfile/builtins.go

@@ -39,6 +39,7 @@ func init() {
 	RegisterDirective("bind", parseBind)
 	RegisterDirective("tls", parseTLS)
 	RegisterHandlerDirective("root", parseRoot)
+	RegisterHandlerDirective("vars", parseVars)
 	RegisterHandlerDirective("redir", parseRedir)
 	RegisterHandlerDirective("respond", parseRespond)
 	RegisterHandlerDirective("abort", parseAbort)
@@ -530,6 +531,13 @@ func parseRoot(h Helper) (caddyhttp.MiddlewareHandler, error) {
 	return caddyhttp.VarsMiddleware{"root": root}, nil
 }
 
+// parseVars parses the vars directive. See its UnmarshalCaddyfile method for syntax.
+func parseVars(h Helper) (caddyhttp.MiddlewareHandler, error) {
+	v := new(caddyhttp.VarsMiddleware)
+	err := v.UnmarshalCaddyfile(h.Dispenser)
+	return v, err
+}
+
 // parseRedir parses the redir directive. Syntax:
 //
 //     redir [<matcher>] <to> [<code>]

caddyconfig/httpcaddyfile/directives.go

@@ -40,6 +40,7 @@ var directiveOrder = []string{
 	"tracing",
 
 	"map",
+	"vars",
 	"root",
 
 	"header",

caddytest/integration/caddyfile_adapt/map_and_vars_with_raw_types.txt

@@ -19,6 +19,14 @@ map {host}             {my_placeholder}  {magic_number} {
 	# Should output two strings, second being escaped quote
 	default            "unknown domain"  \"""
 }
+
+vars foo bar
+vars {
+	abc true
+	def 1
+	ghi 2.3
+	jkl "mn op"
+}
 ----------
 {
 	"apps": {
@@ -91,6 +99,17 @@ map {host}             {my_placeholder}  {magic_number} {
 														}
 													],
 													"source": "{http.request.host}"
+												},
+												{
+													"foo": "bar",
+													"handler": "vars"
+												},
+												{
+													"abc": true,
+													"def": 1,
+													"ghi": 2.3,
+													"handler": "vars",
+													"jkl": "mn op"
 												}
 											]
 										}

modules/caddyhttp/vars.go

@@ -37,7 +37,7 @@ func init() {
 //
 // The key is the variable name, and the value is the value of the
 // variable. Both the name and value may use or contain placeholders.
-type VarsMiddleware map[string]string
+type VarsMiddleware map[string]interface{}
 
 // CaddyModule returns the Caddy module information.
 func (VarsMiddleware) CaddyModule() caddy.ModuleInfo {
@@ -47,17 +47,67 @@ func (VarsMiddleware) CaddyModule() caddy.ModuleInfo {
 	}
 }
 
-func (t VarsMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
+func (m VarsMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
 	vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
-	for k, v := range t {
+	for k, v := range m {
 		keyExpanded := repl.ReplaceAll(k, "")
-		valExpanded := repl.ReplaceAll(v, "")
-		vars[keyExpanded] = valExpanded
+		if valStr, ok := v.(string); ok {
+			v = repl.ReplaceAll(valStr, "")
+		}
+		vars[keyExpanded] = v
 	}
 	return next.ServeHTTP(w, r)
 }
 
+// UnmarshalCaddyfile implements caddyfile.Unmarshaler. Syntax:
+//
+//     vars [<name> <val>] {
+//         <name> <val>
+//         ...
+//     }
+//
+func (m *VarsMiddleware) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
+	if *m == nil {
+		*m = make(VarsMiddleware)
+	}
+
+	nextVar := func(headerLine bool) error {
+		if headerLine {
+			// header line is optional
+			if !d.NextArg() {
+				return nil
+			}
+		}
+		varName := d.Val()
+
+		if !d.NextArg() {
+			return d.ArgErr()
+		}
+		varValue := d.ScalarVal()
+
+		(*m)[varName] = varValue
+
+		if d.NextArg() {
+			return d.ArgErr()
+		}
+		return nil
+	}
+
+	for d.Next() {
+		if err := nextVar(true); err != nil {
+			return err
+		}
+		for nesting := d.Nesting(); d.NextBlock(nesting); {
+			if err := nextVar(false); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
 // VarsMatcher is an HTTP request matcher which can match
 // requests based on variables in the context. The key is
 // the name of the variable, and the values are possible
@@ -262,5 +312,7 @@ func SetVar(ctx context.Context, key string, value interface{}) {
 // Interface guards
 var (
 	_ MiddlewareHandler     = (*VarsMiddleware)(nil)
+	_ caddyfile.Unmarshaler = (*VarsMiddleware)(nil)
 	_ RequestMatcher        = (*VarsMatcher)(nil)
+	_ caddyfile.Unmarshaler = (*VarsMatcher)(nil)
 )