From ed155e47c4f9a2c57acfee0a9a5ca681b5dd2894 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Piotr=20Jamr=C3=B3z?= <pm.jamroz@gmail.com>
Date: Thu, 17 Mar 2022 14:26:08 +0100
Subject: [PATCH] Graphite: Fallback to hardcoded list of functions when no
 functions are returned (#46681)

---
 .../app/plugins/datasource/graphite/datasource.test.ts   | 8 ++++++++
 public/app/plugins/datasource/graphite/datasource.ts     | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/public/app/plugins/datasource/graphite/datasource.test.ts b/public/app/plugins/datasource/graphite/datasource.test.ts
index aa120c42d61..da27191be21 100644
--- a/public/app/plugins/datasource/graphite/datasource.test.ts
+++ b/public/app/plugins/datasource/graphite/datasource.test.ts
@@ -292,6 +292,14 @@ describe('graphiteDatasource', () => {
         },
       });
     });
+
+    it('should use hardcoded list of functions when no functions are returned', async () => {
+      fetchMock.mockImplementation(() => {
+        return of(createFetchResponse('{}'));
+      });
+      const funcDefs = await ctx.ds.getFuncDefs();
+      expect(Object.keys(funcDefs)).not.toHaveLength(0);
+    });
   });
 
   describe('building graphite params', () => {
diff --git a/public/app/plugins/datasource/graphite/datasource.ts b/public/app/plugins/datasource/graphite/datasource.ts
index b33baad6011..f09ea680694 100644
--- a/public/app/plugins/datasource/graphite/datasource.ts
+++ b/public/app/plugins/datasource/graphite/datasource.ts
@@ -769,6 +769,15 @@ export class GraphiteDatasource
           } else {
             this.funcDefs = gfunc.parseFuncDefs(results.data);
           }
+
+          // When /functions endpoint returns application/json response but containing invalid JSON the fix above
+          // wont' be triggered due to the changes in https://github.com/grafana/grafana/pull/45598 (parsing happens
+          // in fetch and Graphite receives an empty object and no error). In such cases, when the provided JSON
+          // seems empty we fallback to the hardcoded list of functions.
+          // See also: https://github.com/grafana/grafana/issues/45948
+          if (Object.keys(this.funcDefs).length === 0) {
+            this.funcDefs = gfunc.getFuncDefs(this.graphiteVersion);
+          }
           return this.funcDefs;
         }),
         catchError((error: any) => {