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

1 files changed, 22 insertions, 7 deletions

diff --git a/caddyconfig/httpcaddyfile/directives.go b/caddyconfig/httpcaddyfile/directives.go
index 6b80e34..aaa8cb0 100644
--- a/caddyconfig/httpcaddyfile/directives.go
+++ b/caddyconfig/httpcaddyfile/directives.go
@@ -424,14 +424,29 @@ func sortRoutes(routes []ConfigValue) {
 			jPathLen = len(jPM[0])
 		}
 
-		// if both directives have no path matcher, use whichever one
-		// has any kind of matcher defined first.
-		if iPathLen == 0 && jPathLen == 0 {
-			return len(iRoute.MatcherSetsRaw) > 0 && len(jRoute.MatcherSetsRaw) == 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 {
+				return len(iRoute.MatcherSetsRaw) > 0 && len(jRoute.MatcherSetsRaw) == 0
+			}
 
-		// sort with the most-specific (longest) path first
-		return iPathLen > jPathLen
+			// sort with the most-specific (longest) path first
+			return iPathLen > jPathLen
+		}
 	})
 }