caddyconfig: Specify config adapter for HTTP loader (close #5607)

1 files changed, 19 insertions, 3 deletions

diff --git a/caddyconfig/httploader.go b/caddyconfig/httploader.go
index 7c4dc2319..e0ce4ebf7 100644
--- a/caddyconfig/httploader.go
+++ b/caddyconfig/httploader.go
@@ -30,8 +30,14 @@ func init() {
 	caddy.RegisterModule(HTTPLoader{})
 }
 
-// HTTPLoader can load Caddy configs over HTTP(S). It can adapt the config
-// based on the Content-Type header of the HTTP response.
+// HTTPLoader can load Caddy configs over HTTP(S).
+//
+// If the response is not a JSON config, a config adapter must be specified
+// either in the loader config (`adapter`), or in the Content-Type HTTP header
+// returned in the HTTP response from the server. The Content-Type header is
+// read just like the admin API's `/load` endpoint. Uf you don't have control
+// over the HTTP server (but can still trust its response), you can override
+// the Content-Type header by setting the `adapter` property in this config.
 type HTTPLoader struct {
 	// The method for the request. Default: GET
 	Method string `json:"method,omitempty"`
@@ -45,6 +51,11 @@ type HTTPLoader struct {
 	// Maximum time allowed for a complete connection and request.
 	Timeout caddy.Duration `json:"timeout,omitempty"`
 
+	// The name of the config adapter to use, if any. Only needed
+	// if the HTTP response is not a JSON config and if the server's
+	// Content-Type header is missing or incorrect.
+	Adapter string `json:"adapter,omitempty"`
+
 	TLS *struct {
 		// Present this instance's managed remote identity credentials to the server.
 		UseServerIdentity bool `json:"use_server_identity,omitempty"`
@@ -108,7 +119,12 @@ func (hl HTTPLoader) LoadConfig(ctx caddy.Context) ([]byte, error) {
 		return nil, err
 	}
 
-	result, warnings, err := adaptByContentType(resp.Header.Get("Content-Type"), body)
+	// adapt the config based on either manually-configured adapter or server's response header
+	ct := resp.Header.Get("Content-Type")
+	if hl.Adapter != "" {
+		ct = "text/" + hl.Adapter
+	}
+	result, warnings, err := adaptByContentType(ct, body)
 	if err != nil {
 		return nil, err
 	}