Graphite: Backend tag values autocomplete endpoint (#110773)

* Add lint rules

* Backend decoupling

- Add standalone files
- Add graphite query type
- Add logger to Service
- Create logger in the ProvideService method
- Use a pointer for the HTTP client provider
- Update logger usage everywhere
- Update tracer type
- Replace simplejson with json
- Add dummy CallResource and CheckHealth methods
- Update tests

* Update ConfigEditor imports

* Update types imports

* Update datasource

- Switch to using semver package
- Update imports

* Update store imports

* Update helper imports and notification creation

* Update context import

* Update version numbers and logic

* Copy array_move from core

* Test updates

* Add required files and update plugin.json

* Update core references and packages

* Remove commented code

* Update wire

* Lint

* Fix import

* Copy null type

* More lint

* Update snapshot

* Refactor backend

- Split query logic into separate file
- Move utils to separate file

* Add health-check logic

- Support backend healthcheck if the FF is enabled

* Remove query import support as unneeded

* Add test

* Add util function for decoding responses

* Add events types

* Add resource handler

* Add events handler and generic resource req handler

* Tests

* Update frontend

- Add types
- Update events function to support backend requests

* Lint and typing

* Lint

* Add metrics find endpoint

- Add types
- Add generic response parser
- Add endpoint
- Tests

* Update FE functoin to use backend endpoint

* Lint

* Simplify request

* Update test

* Metrics expand type

* Extract shared logic and add metric expand endpoint

* Update tests

* Call metric expand from backend

* Rename type for clarity

* Add get resource req handler

* Refactor doGraphiteRequest, parseResponse

Update tests

* Migrate functions endpoint to backend

* Support tags autocomplete in backend

- Add tests
- Add types
- Remove unneeded comments

* Support tag values autocomplete

- Remove unused frontend endpoints
- Add types
- Update tests

* Add tests

* Review

* Review

* Fix packages

* Format

* Fix merge issues

* Review

* Fix undefined values

* Extract request creation

- Add method for create requests generically with tests
- Replace usage in query method
- Update usages in resource handlers
- Update tests
- Update types

* Lint

pkg/tsdb/graphite/graphite_test.go

@@ -26,7 +26,7 @@ func Test_CreateRequest(t *testing.T) {
 		expectedMethod string
 		expectedError  string
 		checkHeaders   map[string]string
-		checkQuery     map[string]string
+		checkQuery     map[string][]string
 	}{
 		{
 			name:           "basic request with default GET method",
@@ -57,16 +57,16 @@ func Test_CreateRequest(t *testing.T) {
 			name:   "request with query parameters",
 			dsInfo: dsInfo,
 			params: URLParams{
-				QueryParams: map[string]string{
-					"query":  "stats.counters.*",
-					"format": "json",
+				QueryParams: map[string][]string{
+					"query":  {"stats.counters.*"},
+					"format": {"json"},
 				},
 			},
 			expectedURL:    "http://graphite.example.com",
 			expectedMethod: "GET",
-			checkQuery: map[string]string{
-				"query":  "stats.counters.*",
-				"format": "json",
+			checkQuery: map[string][]string{
+				"query":  {"stats.counters.*"},
+				"format": {"json"},
 			},
 		},
 		{
@@ -99,9 +99,9 @@ func Test_CreateRequest(t *testing.T) {
 			params: URLParams{
 				SubPath: "/metrics/expand",
 				Method:  "POST",
-				QueryParams: map[string]string{
-					"groupByExpr": "true",
-					"leavesOnly":  "false",
+				QueryParams: map[string][]string{
+					"groupByExpr": {"true"},
+					"leavesOnly":  {"false"},
 				},
 				Headers: map[string]string{
 					"X-Custom-Header": "test-value",
@@ -110,9 +110,9 @@ func Test_CreateRequest(t *testing.T) {
 			},
 			expectedURL:    "http://graphite.example.com/metrics/expand",
 			expectedMethod: "POST",
-			checkQuery: map[string]string{
-				"groupByExpr": "true",
-				"leavesOnly":  "false",
+			checkQuery: map[string][]string{
+				"groupByExpr": {"true"},
+				"leavesOnly":  {"false"},
 			},
 			checkHeaders: map[string]string{
 				"X-Custom-Header": "test-value",
@@ -130,16 +130,30 @@ func Test_CreateRequest(t *testing.T) {
 			name:   "empty query parameter values",
 			dsInfo: dsInfo,
 			params: URLParams{
-				QueryParams: map[string]string{
-					"empty": "",
-					"valid": "value",
+				QueryParams: map[string][]string{
+					"empty": {""},
+					"valid": {"value"},
 				},
 			},
 			expectedURL:    "http://graphite.example.com",
 			expectedMethod: "GET",
-			checkQuery: map[string]string{
-				"empty": "",
-				"valid": "value",
+			checkQuery: map[string][]string{
+				"empty": {""},
+				"valid": {"value"},
+			},
+		},
+		{
+			name:   "multi-valued query parameter",
+			dsInfo: dsInfo,
+			params: URLParams{
+				QueryParams: map[string][]string{
+					"valid": {"value1", "value2"},
+				},
+			},
+			expectedURL:    "http://graphite.example.com",
+			expectedMethod: "GET",
+			checkQuery: map[string][]string{
+				"valid": {"value1", "value2"},
 			},
 		},
 	}
@@ -163,9 +177,13 @@ func Test_CreateRequest(t *testing.T) {
 			assert.Equal(t, tt.expectedMethod, req.Method)
 
 			if tt.checkQuery != nil {
-				for key, expectedValue := range tt.checkQuery {
-					actualValue := req.URL.Query().Get(key)
-					assert.Equal(t, expectedValue, actualValue, "Query parameter %s", key)
+				for key, expectedValues := range tt.checkQuery {
+					actualValue := req.URL.Query()[key]
+					assert.NotZero(t, len(actualValue))
+
+					for _, expectedValue := range expectedValues {
+						assert.Contains(t, actualValue, expectedValue, "Query parameter %s", key)
+					}
 				}
 			}