Support gzipped runtime configurations (#571)

* Support gzipped runtime configurations

Some runtime configs can be too large to fit in one kubernetes
configmap. However, Kubernetes configmaps accept binary data, so we can
gzip the yaml, which offers up to 10x compression.

This adds a new flag to runtimeconfig.Manager's config that enabled gzip
uncompression of the files, disabled by default.

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

* Just check the extension

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

* Fix test

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

* Update CHANGELOG.md

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

---------

Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>

CHANGELOG.md

@@ -222,7 +222,8 @@
 * [EHNANCEMENT] crypto/tls: Support reloading client certificates #537 #552
 * [ENHANCEMENT] Add read only support for ingesters in the ring and lifecycler. #553 #554 #556
 * [ENHANCEMENT] Added new ring methods to expose number of writable instances with tokens per zone, and overall. #560 #562
-* [ENHANCEMENT] `services.FailureWatcher` can now be closed, which unregisters all service and manager listeners, and closes channel used to receive errors. #564 
+* [ENHANCEMENT] `services.FailureWatcher` can now be closed, which unregisters all service and manager listeners, and closes channel used to receive errors. #564
+* [ENHANCEMENT] Runtimeconfig: support gzip-compressed files with `.gz` extension. #571
 * [CHANGE] Backoff: added `Backoff.ErrCause()` which is like `Backoff.Err()` but returns the context cause if backoff is terminated because the context has been canceled. #538
 * [BUGFIX] spanlogger: Support multiple tenant IDs. #59
 * [BUGFIX] Memberlist: fixed corrupted packets when sending compound messages with more than 255 messages or messages bigger than 64KB. #85

runtimeconfig/manager.go

@@ -2,12 +2,14 @@ package runtimeconfig
 
 import (
 	"bytes"
+	"compress/gzip"
 	"context"
 	"crypto/sha256"
 	"flag"
 	"fmt"
 	"io"
 	"os"
+	"strings"
 	"sync"
 	"time"
 
@@ -183,8 +185,8 @@ func (om *Manager) loadConfig() error {
 
 	mergedConfig := map[string]interface{}{}
 	for _, f := range om.cfg.LoadPath {
-		yamlFile := map[string]interface{}{}
-		err := yaml.Unmarshal(rawData[f], &yamlFile)
+		data := rawData[f]
+		yamlFile, err := om.unmarshalMaybeGzipped(f, data)
 		if err != nil {
 			om.configLoadSuccess.Set(0)
 			return errors.Wrapf(err, "unmarshal file %q", f)
@@ -218,6 +220,32 @@ func (om *Manager) loadConfig() error {
 	return nil
 }
 
+func (om *Manager) unmarshalMaybeGzipped(filename string, data []byte) (map[string]any, error) {
+	yamlFile := map[string]any{}
+	if strings.HasSuffix(filename, ".gz") {
+		r, err := gzip.NewReader(bytes.NewReader(data))
+		if err != nil {
+			return nil, errors.Wrap(err, "read gzipped file")
+		}
+		defer r.Close()
+		err = yaml.NewDecoder(r).Decode(&yamlFile)
+		return yamlFile, errors.Wrap(err, "uncompress/unmarshal gzipped file")
+	}
+
+	if err := yaml.Unmarshal(data, &yamlFile); err != nil {
+		// Give a hint if we think that file is gzipped.
+		if isGzip(data) {
+			return nil, errors.Wrap(err, "file looks gzipped but doesn't have a .gz extension")
+		}
+		return nil, err
+	}
+	return yamlFile, nil
+}
+
+func isGzip(data []byte) bool {
+	return len(data) > 2 && data[0] == 0x1f && data[1] == 0x8b
+}
+
 func mergeConfigMaps(a, b map[string]interface{}) map[string]interface{} {
 	out := make(map[string]interface{}, len(a))
 	for k, v := range a {

runtimeconfig/manager_test.go

@@ -1,11 +1,13 @@
 package runtimeconfig
 
 import (
+	"compress/gzip"
 	"context"
 	"crypto/sha256"
 	"fmt"
 	"io"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -176,6 +178,71 @@ func TestNewOverridesManager(t *testing.T) {
 	require.Equal(t, 150, conf.Overrides["user1"].Limit2)
 }
 
+func TestManagerGzip(t *testing.T) {
+	writeConfig := func(filename string, gzipped bool) string {
+		dir := t.TempDir()
+		filePath := filepath.Join(dir, filename)
+		f, err := os.Create(filePath)
+		require.NoError(t, err)
+		defer f.Close()
+		w := io.Writer(f)
+		if gzipped {
+			gw := gzip.NewWriter(f)
+			defer gw.Close()
+			w = gw
+		}
+		require.NoError(t, yaml.NewEncoder(w).Encode(map[string]any{
+			"overrides": map[string]any{
+				"user1": map[string]any{
+					"limit2": 150,
+				},
+			},
+		}))
+		return filePath
+	}
+
+	cfg := func(file string) Config {
+		return Config{
+			ReloadPeriod: time.Second,
+			LoadPath:     []string{file},
+			Loader:       testLoadOverrides,
+		}
+	}
+
+	defaultTestLimits = &TestLimits{Limit1: 100}
+	t.Run("gzipped with .gz extension should succeed", func(t *testing.T) {
+		file := writeConfig("overrides.yaml.gz", true)
+		manager, err := New(cfg(file), "overrides", nil, log.NewNopLogger())
+		require.NoError(t, err)
+		require.NoError(t, services.StartAndAwaitRunning(context.Background(), manager))
+		t.Cleanup(func() { require.NoError(t, services.StopAndAwaitTerminated(context.Background(), manager)) })
+
+		// Make sure test limits were loaded.
+		require.NotNil(t, manager.GetConfig())
+		conf := manager.GetConfig().(*testOverrides)
+		require.NotNil(t, conf)
+		require.Equal(t, 150, conf.Overrides["user1"].Limit2)
+	})
+
+	t.Run("non-gzipped with .gz extension should fail", func(t *testing.T) {
+		file := writeConfig("overrides.yaml.gz", false)
+		manager, err := New(cfg(file), "overrides", nil, log.NewNopLogger())
+		require.NoError(t, err)
+		err = services.StartAndAwaitRunning(context.Background(), manager)
+		require.Error(t, err)
+		require.ErrorIs(t, err, gzip.ErrHeader)
+	})
+
+	t.Run("gzipped without .gz extension should mention that in the error", func(t *testing.T) {
+		file := writeConfig("overrides.yaml", true)
+		manager, err := New(cfg(file), "overrides", nil, log.NewNopLogger())
+		require.NoError(t, err)
+		err = services.StartAndAwaitRunning(context.Background(), manager)
+		require.Error(t, err)
+		require.Contains(t, err.Error(), "file looks gzipped but doesn't have a .gz extension")
+	})
+}
+
 func TestOverridesManagerMultipleFilesAppend(t *testing.T) {
 	tempFiles, err := generateRuntimeFiles(t,
 		[]string{`overrides: