Make URLHostParserBuilder support a basepath setting (#7700)

This will allow modules using URLHostParserBuilder to support a setting named "basepath" in their configuration. If users set this setting to some value, the value will be inserted into the HTTP URI as the first path segment.

CHANGELOG.asciidoc

@@ -323,6 +323,7 @@ https://github.com/elastic/beats/compare/v6.2.3...master[Check the HEAD diff]
 - Add envoyproxy module. {pull}7569[7569]
 - Release prometheus collector metricset as GA. {pull}7660[7660]
 - Add Elasticsearch `cluster_stats` metricset. {pull}7638[7638]
+- Added `basepath` setting for HTTP-based metricsets {pull}7700[7700]
 
 *Packetbeat*
 

metricbeat/docs/metricbeat-options.asciidoc

@@ -221,4 +221,10 @@ The password to use for basic authentication.
 ==== `bearer_token_file`
 
 If defined, Metricbeat will read the contents of the file once at initialization
-and then use the value in an HTTP Authorization header.
+and then use the value in an HTTP Authorization header.
+
+[float]
+==== `basepath`
+
+An optional base path to be used in HTTP URIs. If defined, Metricbeat will insert this value
+as the first segment in the HTTP URI path.

metricbeat/mb/parse/url.go

@@ -32,13 +32,12 @@ import (
 // URLHostParserBuilder builds a tailored HostParser for used with host strings
 // that are URLs.
 type URLHostParserBuilder struct {
-	BasePathConfigKey string
-	PathConfigKey     string
-	DefaultPath       string
-	DefaultUsername   string
-	DefaultPassword   string
-	DefaultScheme     string
-	QueryParams       string
+	PathConfigKey   string
+	DefaultPath     string
+	DefaultUsername string
+	DefaultPassword string
+	DefaultScheme   string
+	QueryParams     string
 }
 
 // Build returns a new HostParser function whose behavior is influenced by the
@@ -82,11 +81,11 @@ func (b URLHostParserBuilder) Build() mb.HostParser {
 		// Normalize path
 		path = strings.Trim(path, "/")
 
-		t, ok = conf[b.BasePathConfigKey]
+		t, ok = conf["basepath"]
 		if ok {
 			basePath, ok = t.(string)
 			if !ok {
-				return mb.HostData{}, errors.Errorf("'%v' config for module %v is not a string", b.BasePathConfigKey, module.Name())
+				return mb.HostData{}, errors.Errorf("'basepath' config for module %v is not a string", module.Name())
 			}
 		}
 		// Normalize basepath

metricbeat/mb/parse/url_test.go

@@ -114,10 +114,10 @@ func TestURLHostParserBuilder(t *testing.T) {
 		{map[string]interface{}{}, URLHostParserBuilder{DefaultPath: "/default"}, "http://example.com/default"},
 		{map[string]interface{}{"username": "guest"}, URLHostParserBuilder{}, "http://[email protected]"},
 		{map[string]interface{}{"username": "guest", "password": "secret"}, URLHostParserBuilder{}, "http://guest:[email protected]"},
-		{map[string]interface{}{"basepath": "/foo"}, URLHostParserBuilder{BasePathConfigKey: "basepath", DefaultPath: "/default"}, "http://example.com/foo/default"},
-		{map[string]interface{}{"basepath": "foo/"}, URLHostParserBuilder{BasePathConfigKey: "basepath", DefaultPath: "/default"}, "http://example.com/foo/default"},
-		{map[string]interface{}{"basepath": "/foo/"}, URLHostParserBuilder{BasePathConfigKey: "basepath", DefaultPath: "/default"}, "http://example.com/foo/default"},
-		{map[string]interface{}{"basepath": "foo"}, URLHostParserBuilder{BasePathConfigKey: "basepath", DefaultPath: "/default"}, "http://example.com/foo/default"},
+		{map[string]interface{}{"basepath": "/foo"}, URLHostParserBuilder{DefaultPath: "/default"}, "http://example.com/foo/default"},
+		{map[string]interface{}{"basepath": "foo/"}, URLHostParserBuilder{DefaultPath: "/default"}, "http://example.com/foo/default"},
+		{map[string]interface{}{"basepath": "/foo/"}, URLHostParserBuilder{DefaultPath: "/default"}, "http://example.com/foo/default"},
+		{map[string]interface{}{"basepath": "foo"}, URLHostParserBuilder{DefaultPath: "/default"}, "http://example.com/foo/default"},
 	}
 
 	for _, test := range cases {

metricbeat/module/kibana/stats/_meta/docs.asciidoc

@@ -1,3 +1,7 @@
 This is the `stats` metricset of the Kibana module. This stats endpoint is available in 6.4 by default.
 
 The intention of the Kibana module is to have a minimal data set that works across Kibana versions.
+
+=== Module-specific configuration notes
+
+If the Kibana instance is using a basepath in its URL, you must set the `basepath` setting for this module with the same value.

metricbeat/module/kibana/stats/stats.go

@@ -35,10 +35,9 @@ func init() {
 
 var (
 	hostParser = parse.URLHostParserBuilder{
-		DefaultScheme:     "http",
-		BasePathConfigKey: "basepath",
-		DefaultPath:       "api/stats",
-		QueryParams:       "extended=true", // make Kibana fetch the cluster_uuid
+		DefaultScheme: "http",
+		DefaultPath:   "api/stats",
+		QueryParams:   "extended=true", // make Kibana fetch the cluster_uuid
 	}.Build()
 )