Add storage.Warnings to LabelValues and LabelNames (#5673)

Fixes #5661
Signed-off-by: NThomas Jackson <jacksontj.89@gmail.com>

promql/engine_test.go

@@ -173,9 +173,9 @@ type errQuerier struct {
 func (q *errQuerier) Select(*storage.SelectParams, ...*labels.Matcher) (storage.SeriesSet, storage.Warnings, error) {
 	return errSeriesSet{err: q.err}, nil, q.err
 }
-func (*errQuerier) LabelValues(name string) ([]string, error) { return nil, nil }
-func (*errQuerier) LabelNames() ([]string, error)             { return nil, nil }
-func (*errQuerier) Close() error                              { return nil }
+func (*errQuerier) LabelValues(name string) ([]string, storage.Warnings, error) { return nil, nil, nil }
+func (*errQuerier) LabelNames() ([]string, storage.Warnings, error)             { return nil, nil, nil }
+func (*errQuerier) Close() error                                                { return nil }
 
 // errSeriesSet implements storage.SeriesSet which always returns error.
 type errSeriesSet struct {
@@ -242,9 +242,11 @@ func (q *paramCheckerQuerier) Select(sp *storage.SelectParams, _ ...*labels.Matc
 
 	return errSeriesSet{err: nil}, nil, nil
 }
-func (*paramCheckerQuerier) LabelValues(name string) ([]string, error) { return nil, nil }
-func (*paramCheckerQuerier) LabelNames() ([]string, error)             { return nil, nil }
-func (*paramCheckerQuerier) Close() error                              { return nil }
+func (*paramCheckerQuerier) LabelValues(name string) ([]string, storage.Warnings, error) {
+	return nil, nil, nil
+}
+func (*paramCheckerQuerier) LabelNames() ([]string, storage.Warnings, error) { return nil, nil, nil }
+func (*paramCheckerQuerier) Close() error                                    { return nil }
 
 func TestParamsSetCorrectly(t *testing.T) {
 	opts := EngineOpts{

storage/fanout.go

@@ -253,16 +253,28 @@ func (q *mergeQuerier) Select(params *SelectParams, matchers ...*labels.Matcher)
 }
 
 // LabelValues returns all potential values for a label name.
-func (q *mergeQuerier) LabelValues(name string) ([]string, error) {
+func (q *mergeQuerier) LabelValues(name string) ([]string, Warnings, error) {
 	var results [][]string
+	var warnings Warnings
 	for _, querier := range q.queriers {
-		values, err := querier.LabelValues(name)
+		values, wrn, err := querier.LabelValues(name)
+
+		if wrn != nil {
+			warnings = append(warnings, wrn...)
+		}
 		if err != nil {
-			return nil, err
+			q.failedQueriers[querier] = struct{}{}
+			// If the error source isn't the primary querier, return the error as a warning and continue.
+			if querier != q.primaryQuerier {
+				warnings = append(warnings, err)
+				continue
+			} else {
+				return nil, nil, err
+			}
 		}
 		results = append(results, values)
 	}
-	return mergeStringSlices(results), nil
+	return mergeStringSlices(results), warnings, nil
 }
 
 func (q *mergeQuerier) IsFailedSet(set SeriesSet) bool {
@@ -310,13 +322,25 @@ func mergeTwoStringSlices(a, b []string) []string {
 }
 
 // LabelNames returns all the unique label names present in the block in sorted order.
-func (q *mergeQuerier) LabelNames() ([]string, error) {
+func (q *mergeQuerier) LabelNames() ([]string, Warnings, error) {
 	labelNamesMap := make(map[string]struct{})
+	var warnings Warnings
 	for _, b := range q.queriers {
-		names, err := b.LabelNames()
+		names, wrn, err := b.LabelNames()
+		if wrn != nil {
+			warnings = append(warnings, wrn...)
+		}
+
 		if err != nil {
-			return nil, errors.Wrap(err, "LabelNames() from Querier")
+			// If the error source isn't the primary querier, return the error as a warning and continue.
+			if b != q.primaryQuerier {
+				warnings = append(warnings, err)
+				continue
+			} else {
+				return nil, nil, errors.Wrap(err, "LabelNames() from Querier")
+			}
 		}
+
 		for _, name := range names {
 			labelNamesMap[name] = struct{}{}
 		}
@@ -328,7 +352,7 @@ func (q *mergeQuerier) LabelNames() ([]string, error) {
 	}
 	sort.Strings(labelNames)
 
-	return labelNames, nil
+	return labelNames, warnings, nil
 }
 
 // Close releases the resources of the Querier.

storage/interface.go

@@ -55,10 +55,10 @@ type Querier interface {
 	Select(*SelectParams, ...*labels.Matcher) (SeriesSet, Warnings, error)
 
 	// LabelValues returns all potential values for a label name.
-	LabelValues(name string) ([]string, error)
+	LabelValues(name string) ([]string, Warnings, error)
 
 	// LabelNames returns all the unique label names present in the block in sorted order.
-	LabelNames() ([]string, error)
+	LabelNames() ([]string, Warnings, error)
 
 	// Close releases the resources of the Querier.
 	Close() error

storage/noop.go

@@ -30,12 +30,12 @@ func (noopQuerier) Select(*SelectParams, ...*labels.Matcher) (SeriesSet, Warning
 	return NoopSeriesSet(), nil, nil
 }
 
-func (noopQuerier) LabelValues(name string) ([]string, error) {
-	return nil, nil
+func (noopQuerier) LabelValues(name string) ([]string, Warnings, error) {
+	return nil, nil, nil
 }
 
-func (noopQuerier) LabelNames() ([]string, error) {
-	return nil, nil
+func (noopQuerier) LabelNames() ([]string, Warnings, error) {
+	return nil, nil, nil
 }
 
 func (noopQuerier) Close() error {

storage/remote/read.go

@@ -77,15 +77,15 @@ func (q *querier) Select(p *storage.SelectParams, matchers ...*labels.Matcher) (
 }
 
 // LabelValues implements storage.Querier and is a noop.
-func (q *querier) LabelValues(name string) ([]string, error) {
+func (q *querier) LabelValues(name string) ([]string, storage.Warnings, error) {
 	// TODO implement?
-	return nil, nil
+	return nil, nil, nil
 }
 
 // LabelNames implements storage.Querier and is a noop.
-func (q *querier) LabelNames() ([]string, error) {
+func (q *querier) LabelNames() ([]string, storage.Warnings, error) {
 	// TODO implement?
-	return nil, nil
+	return nil, nil, nil
 }
 
 // Close implements storage.Querier and is a noop.

storage/tsdb/tsdb.go

@@ -253,9 +253,15 @@ func (q querier) Select(_ *storage.SelectParams, oms ...*labels.Matcher) (storag
 	return seriesSet{set: set}, nil, nil
 }
 
-func (q querier) LabelValues(name string) ([]string, error) { return q.q.LabelValues(name) }
-func (q querier) LabelNames() ([]string, error)             { return q.q.LabelNames() }
-func (q querier) Close() error                              { return q.q.Close() }
+func (q querier) LabelValues(name string) ([]string, storage.Warnings, error) {
+	v, err := q.q.LabelValues(name)
+	return v, nil, err
+}
+func (q querier) LabelNames() ([]string, storage.Warnings, error) {
+	v, err := q.q.LabelNames()
+	return v, nil, err
+}
+func (q querier) Close() error { return q.q.Close() }
 
 type seriesSet struct {
 	set tsdb.SeriesSet

web/api/v1/api.go

@@ -410,11 +410,11 @@ func (api *API) labelNames(r *http.Request) apiFuncResult {
 	}
 	defer q.Close()
 
-	names, err := q.LabelNames()
+	names, warnings, err := q.LabelNames()
 	if err != nil {
-		return apiFuncResult{nil, &apiError{errorExec, err}, nil, nil}
+		return apiFuncResult{nil, &apiError{errorExec, err}, warnings, nil}
 	}
-	return apiFuncResult{names, nil, nil, nil}
+	return apiFuncResult{names, nil, warnings, nil}
 }
 
 func (api *API) labelValues(r *http.Request) apiFuncResult {
@@ -430,12 +430,12 @@ func (api *API) labelValues(r *http.Request) apiFuncResult {
 	}
 	defer q.Close()
 
-	vals, err := q.LabelValues(name)
+	vals, warnings, err := q.LabelValues(name)
 	if err != nil {
-		return apiFuncResult{nil, &apiError{errorExec, err}, nil, nil}
+		return apiFuncResult{nil, &apiError{errorExec, err}, warnings, nil}
 	}
 
-	return apiFuncResult{vals, nil, nil, nil}
+	return apiFuncResult{vals, nil, warnings, nil}
 }
 
 var (