From 9df8c4fe86a7fb3b10abba9b282913df6d269b90 Mon Sep 17 00:00:00 2001
From: David Kaltschmidt <david.kaltschmidt@gmail.com>
Date: Tue, 24 Apr 2018 16:26:46 +0200
Subject: [PATCH] force GET for metadataRequests, w/ test

(cherry picked from commit 707700ac7dd1d938f281c110113d274907417692)
---
 .../datasource/prometheus/datasource.ts       |  2 +-
 .../prometheus/specs/datasource.jest.ts       | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/public/app/plugins/datasource/prometheus/datasource.ts b/public/app/plugins/datasource/prometheus/datasource.ts
index 3a2c78dce2d..cbf701a0abe 100644
--- a/public/app/plugins/datasource/prometheus/datasource.ts
+++ b/public/app/plugins/datasource/prometheus/datasource.ts
@@ -84,7 +84,7 @@ export class PrometheusDatasource {
 
   // Use this for tab completion features, wont publish response to other components
   metadataRequest(url) {
-    return this._request(url, null, { silent: true });
+    return this._request(url, null, { method: 'GET', silent: true });
   }
 
   interpolateQueryExpr(value, variable, defaultFormatFn) {
diff --git a/public/app/plugins/datasource/prometheus/specs/datasource.jest.ts b/public/app/plugins/datasource/prometheus/specs/datasource.jest.ts
index d2620b93bbc..a997a2d8233 100644
--- a/public/app/plugins/datasource/prometheus/specs/datasource.jest.ts
+++ b/public/app/plugins/datasource/prometheus/specs/datasource.jest.ts
@@ -14,6 +14,7 @@ describe('PrometheusDatasource', () => {
   };
 
   ctx.backendSrvMock = {};
+
   ctx.templateSrvMock = {
     replace: a => a,
   };
@@ -23,6 +24,25 @@ describe('PrometheusDatasource', () => {
     ctx.ds = new PrometheusDatasource(instanceSettings, q, ctx.backendSrvMock, ctx.templateSrvMock, ctx.timeSrvMock);
   });
 
+  describe('Datasource metadata requests', () => {
+    it('should perform a GET request with the default config', () => {
+      ctx.backendSrvMock.datasourceRequest = jest.fn();
+      ctx.ds.metadataRequest('/foo');
+      expect(ctx.backendSrvMock.datasourceRequest.mock.calls.length).toBe(1);
+      expect(ctx.backendSrvMock.datasourceRequest.mock.calls[0][0].method).toBe('GET');
+    });
+
+    it('should still perform a GET request with the DS HTTP method set to POST', () => {
+      ctx.backendSrvMock.datasourceRequest = jest.fn();
+      const postSettings = _.cloneDeep(instanceSettings);
+      postSettings.jsonData.httpMethod = 'POST';
+      const ds = new PrometheusDatasource(postSettings, q, ctx.backendSrvMock, ctx.templateSrvMock, ctx.timeSrvMock);
+      ds.metadataRequest('/foo');
+      expect(ctx.backendSrvMock.datasourceRequest.mock.calls.length).toBe(1);
+      expect(ctx.backendSrvMock.datasourceRequest.mock.calls[0][0].method).toBe('GET');
+    });
+  });
+
   describe('When converting prometheus histogram to heatmap format', () => {
     beforeEach(() => {
       ctx.query = {