httpcaddyfile: Add {vars.*} placeholder shortcut, reverse vars sort order (#4726)

* httpcaddyfile: Add `{vars.*}` placeholder shortcut

I'm yoinking this from my https://github.com/caddyserver/caddy/pull/4657 PR because I think we should get this in ASAP for v2.5.0 along with the new `vars` directive.

* Sort vars by matchers in reverse

caddyconfig/httpcaddyfile/directives.go

@@ -424,6 +424,20 @@ func sortRoutes(routes []ConfigValue) {
 			jPathLen = len(jPM[0])
 		}
 
+		// some directives involve setting values which can overwrite
+		// eachother, so it makes most sense to reverse the order so
+		// that the lease specific matcher is first; everything else
+		// has most-specific matcher first
+		if iDir == "vars" {
+			// if both directives have no path matcher, use whichever one
+			// has no matcher first.
+			if iPathLen == 0 && jPathLen == 0 {
+				return len(iRoute.MatcherSetsRaw) == 0 && len(jRoute.MatcherSetsRaw) > 0
+			}
+
+			// sort with the least-specific (shortest) path first
+			return iPathLen < jPathLen
+		} else {
 			// if both directives have no path matcher, use whichever one
 			// has any kind of matcher defined first.
 			if iPathLen == 0 && jPathLen == 0 {
@@ -432,6 +446,7 @@ func sortRoutes(routes []ConfigValue) {
 
 			// sort with the most-specific (longest) path first
 			return iPathLen > jPathLen
+		}
 	})
 }
 

caddyconfig/httpcaddyfile/httptype.go

@@ -129,6 +129,7 @@ func (st ServerType) Setup(inputServerBlocks []caddyfile.ServerBlock,
 		{regexp.MustCompile(`{header\.([\w-]*)}`), "{http.request.header.$1}"},
 		{regexp.MustCompile(`{path\.([\w-]*)}`), "{http.request.uri.path.$1}"},
 		{regexp.MustCompile(`{re\.([\w-]*)\.([\w-]*)}`), "{http.regexp.$1.$2}"},
+		{regexp.MustCompile(`{vars\.([\w-]*)}`), "{http.vars.$1}"},
 	}
 
 	for _, sb := range originalServerBlocks {

caddytest/integration/caddyfile_adapt/sort_vars_in_reverse.txt

@@ -0,0 +1,59 @@
+:80
+
+vars /foobar foo last
+vars /foo foo middle
+vars * foo first
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":80"
+					],
+					"routes": [
+						{
+							"handle": [
+								{
+									"foo": "first",
+									"handler": "vars"
+								}
+							]
+						},
+						{
+							"match": [
+								{
+									"path": [
+										"/foo"
+									]
+								}
+							],
+							"handle": [
+								{
+									"foo": "middle",
+									"handler": "vars"
+								}
+							]
+						},
+						{
+							"match": [
+								{
+									"path": [
+										"/foobar"
+									]
+								}
+							],
+							"handle": [
+								{
+									"foo": "last",
+									"handler": "vars"
+								}
+							]
+						}
+					]
+				}
+			}
+		}
+	}
+}