Annotations does not support templating variables (Prometheus datasource does)

[Dawid Gosławski]

When using dynamic datasource for annotation like "${datasource}" the Datasource won't be found and query will fail

Also when query itself has templating like my_counter{db="$db"} the value is sent raw so it's not functional

[Dawid Gosławski]

The source of these problems are two:

1. Datasource is always taken raw, I tested fix by adding to datasource.tsx:705:

if (datasource?.uid?.startsWith("$") === true){
      datasource.uid = this.templateSrv.replace(datasource.uid, {});
    };

2. Variables templating is discarded in this section:

if (request.targets.every(t => t.refId === "Anno")) {
  const query = request.targets[0] as PromQueryRequest
  return this.performAnnotationQuery({ ...query, start, end })
}

this discards all query preparation done by prepareTargets / createQuery which has query.expr = this.templateSrv.replace(expr, scopedVars, this.interpolateQueryExpr); and takes raw input from target instead, fixed by:

       if (request.targets.every(t => t.refId === "Anno")) {
-        const query = request.targets[0] as PromQueryRequest
+        const query = {...request.targets[0], expr: queries[0].expr} as PromQueryRequest
         return this.performAnnotationQuery({ ...query, start, end })
       }

I am not javascript expert so these fixes can be raw, but generally after adding these both Datasource and Expression templating works as intended.

[Yury Molodov]

This issue has been fixed in datasource starting from v0.8.0. Closing the issue as fixed. Thanks @dg-nvm!