Various tweaks

- Allow specification of target in config file.
- Allow sepcification of HTTP prefix (/api/prom), so we can drop it to look like a 'normal' prometheus.
- Fix forwarding request to normal Prometheus.

Signed-off-by: Tom Wilkie <[email protected]>

Author: tomwilkie

pkg/cortex/cortex.go

@@ -53,6 +53,7 @@ type Config struct {
 	Target      moduleName `yaml:"target,omitempty"`
 	AuthEnabled bool       `yaml:"auth_enabled,omitempty"`
 	PrintConfig bool       `yaml:"-"`
+	HTTPPrefix  string     `yaml:"http_prefix"`
 
 	Server         server.Config            `yaml:"server,omitempty"`
 	Distributor    distributor.Config       `yaml:"distributor,omitempty"`
@@ -82,6 +83,7 @@ func (c *Config) RegisterFlags(f *flag.FlagSet) {
 	f.Var(&c.Target, "target", "target module (default All)")
 	f.BoolVar(&c.AuthEnabled, "auth.enabled", true, "Set to false to disable auth.")
 	f.BoolVar(&c.PrintConfig, "print.config", false, "Print the config and exit.")
+	f.StringVar(&c.HTTPPrefix, "http.prefix", "/api/prom", "HTTP path prefix for Cortex API.")
 
 	c.Server.RegisterFlags(f)
 	c.Distributor.RegisterFlags(f)

pkg/cortex/modules.go

@@ -132,6 +132,14 @@ func (m *moduleName) Set(s string) error {
 	}
 }
 
+func (m *moduleName) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+	return m.Set(s)
+}
+
 func (t *Cortex) initServer(cfg *Config) (err error) {
 	t.server, err = server.New(cfg.Server)
 	return
@@ -259,7 +267,7 @@ func (t *Cortex) initQueryFrontend(cfg *Config) (err error) {
 	}
 
 	frontend.RegisterFrontendServer(t.server.GRPC, t.frontend)
-	t.server.HTTP.PathPrefix("/api/prom").Handler(
+	t.server.HTTP.PathPrefix(cfg.HTTPPrefix).Handler(
 		t.httpAuthMiddleware.Wrap(
 			t.frontend.Handler(),
 		),

pkg/querier/frontend/frontend.go

@@ -71,7 +71,7 @@ func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
 	f.BoolVar(&cfg.CacheResults, "querier.cache-results", false, "Cache query results.")
 	f.BoolVar(&cfg.CompressResponses, "querier.compress-http-responses", false, "Compress HTTP responses.")
 	cfg.ResultsCacheConfig.RegisterFlags(f)
-	f.StringVar(&cfg.DownstreamURL, "querier.downstream-url", "", "URL of downstream Prometheus.")
+	f.StringVar(&cfg.DownstreamURL, "frontend.downstream-url", "", "URL of downstream Prometheus.")
 }
 
 // Frontend queues HTTP requests, dispatches them to backends, and handles retries
@@ -135,6 +135,7 @@ func New(cfg Config, log log.Logger, limits *validation.Overrides) (*Frontend, e
 		}
 
 		roundTripper = RoundTripFunc(func(r *http.Request) (*http.Response, error) {
+			r.URL.Scheme = u.Scheme
 			r.URL.Host = u.Host
 			r.URL.Path = path.Join(u.Path, r.URL.Path)
 			return http.DefaultTransport.RoundTrip(r)
@@ -144,8 +145,8 @@ func New(cfg Config, log log.Logger, limits *validation.Overrides) (*Frontend, e
 	// Finally, if the user selected any query range middleware, stitch it in.
 	if len(queryRangeMiddleware) > 0 {
 		roundTripper = queryrange.NewRoundTripper(
-			f,
-			queryrange.MergeMiddlewares(queryRangeMiddleware...).Wrap(&queryrange.ToRoundTripperMiddleware{Next: f}),
+			roundTripper,
+			queryrange.MergeMiddlewares(queryRangeMiddleware...).Wrap(&queryrange.ToRoundTripperMiddleware{Next: roundTripper}),
 			limits,
 		)
 	}