Add support for consul path_prefix

Signed-off-by: Julien Pivotto <roidelapluie@o11y.eu>

config/config_test.go

@@ -363,6 +363,7 @@ var expectedConf = &Config{
 			ServiceDiscoveryConfigs: discovery.Configs{
 				&consul.SDConfig{
 					Server:          "localhost:1234",
+					PathPrefix:      "/consul",
 					Token:           "mysecret",
 					Services:        []string{"nginx", "cache", "mysql"},
 					ServiceTags:     []string{"canary", "v1"},

config/testdata/conf.good.yml

@@ -151,6 +151,7 @@ scrape_configs:
     consul_sd_configs:
       - server: "localhost:1234"
         token: mysecret
+        path_prefix: /consul
         services: ["nginx", "cache", "mysql"]
         tags: ["canary", "v1"]
         node_meta:

discovery/consul/consul.go

@@ -111,6 +111,7 @@ func init() {
 // SDConfig is the configuration for Consul service discovery.
 type SDConfig struct {
 	Server       string        `yaml:"server,omitempty"`
+	PathPrefix   string        `yaml:"path_prefix,omitempty"`
 	Token        config.Secret `yaml:"token,omitempty"`
 	Datacenter   string        `yaml:"datacenter,omitempty"`
 	Namespace    string        `yaml:"namespace,omitempty"`
@@ -211,6 +212,7 @@ func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
 
 	clientConf := &consul.Config{
 		Address:    conf.Server,
+		PathPrefix: conf.PathPrefix,
 		Scheme:     conf.Scheme,
 		Datacenter: conf.Datacenter,
 		Namespace:  conf.Namespace,

docs/configuration/configuration.md

@@ -585,6 +585,8 @@ The following meta labels are available on targets during [relabeling](#relabel_
 # The information to access the Consul API. It is to be defined
 # as the Consul documentation requires.
 [ server: <host> | default = "localhost:8500" ]
+# Prefix for URIs for when consul is behind an API gateway (reverse proxy).
+[ path_prefix: <string> ]
 [ token: <secret> ]
 [ datacenter: <string> ]
 # Namespaces are only supported in Consul Enterprise.