Runtime config endpoint now supports diff parameter

CHANGELOG.md

@@ -8,6 +8,7 @@
   * Avoid unnecessary `runtime.GC()` during compactions.
   * Prevent compaction loop in TSDB on data gap.
 * [ENHANCEMENT] Return server side performance metrics for query-frontend (using Server-timing header). #3685
+* [ENHANCEMENT] Runtime Config: Add a `mode` query parameter for the runtime config endpoint. `/runtime_config?mode=diff` now shows the YAML runtime configuration with all values that differ from the defaults. #3700
 * [BUGFIX] HA Tracker: don't track as error in the `cortex_kv_request_duration_seconds` metric a CAS operation intentionally aborted. #3745
 
 ## 1.7.0 in progress

docs/api/_index.md

@@ -117,7 +117,7 @@ Displays the configuration currently applied to Cortex (in YAML format), includi
 GET /config?mode=diff
 ```
 
-Displays the configuration currently applied to Cortex (in YAML format) as before, but containing only the values that differ from the  default values.
+Displays the configuration currently applied to Cortex (in YAML format) as before, but containing only the values that differ from the default values.
 
 ```
 GET /config?mode=defaults
@@ -133,6 +133,14 @@ GET /runtime_config
 
 Displays the runtime configuration currently applied to Cortex (in YAML format), including default values. Please be aware that the endpoint will be only available if Cortex is configured with the `-runtime-config.file` option.
 
+#### Different modes
+
+```
+GET /runtime_config?mode=diff
+```
+
+Displays the runtime configuration currently applied to Cortex (in YAML format) as before, but containing only the values that differ from the default values.
+
 ### Services status
 
 ```

docs/configuration/arguments.md

@@ -422,7 +422,7 @@ multi_kv_config:
 
 When running Cortex on Kubernetes, store this file in a config map and mount it in each services' containers.  When changing the values there is no need to restart the services, unless otherwise specified.
 
-The `/runtime_config` endpoint returns the runtime configuration, including the overrides.
+The `/runtime_config` endpoint returns the whole runtime configuration, including the overrides. In case you want to get only the non-default values of the configuration you can pass the `mode` parameter with the `diff` value.
 
 ## Ingester, Distributor & Querier limits.
 

pkg/api/api.go

@@ -33,7 +33,6 @@ import (
 	"github.com/cortexproject/cortex/pkg/storegateway"
 	"github.com/cortexproject/cortex/pkg/storegateway/storegatewaypb"
 	"github.com/cortexproject/cortex/pkg/util/push"
-	"github.com/cortexproject/cortex/pkg/util/runtimeconfig"
 )
 
 type Config struct {
@@ -179,10 +178,11 @@ func (a *API) RegisterAPI(httpPathPrefix string, actualCfg interface{}, defaultC
 }
 
 // RegisterRuntimeConfig registers the endpoints associates with the runtime configuration
-func (a *API) RegisterRuntimeConfig(runtimeCfgManager *runtimeconfig.Manager) {
+func (a *API) RegisterRuntimeConfig(runtimeConfigHandler http.HandlerFunc) {
 	a.indexPage.AddLink(SectionAdminEndpoints, "/runtime_config", "Current Runtime Config (incl. Overrides)")
+	a.indexPage.AddLink(SectionAdminEndpoints, "/runtime_config?mode=diff", "Current Runtime Config (show only values that differ from the defaults)")
 
-	a.RegisterRoute("/runtime_config", runtimeConfigHandler(runtimeCfgManager), false, "GET")
+	a.RegisterRoute("/runtime_config", runtimeConfigHandler, false, "GET")
 }
 
 // RegisterDistributor registers the endpoints associated with the distributor.

pkg/api/handlers.go

@@ -2,11 +2,9 @@ package api
 
 import (
 	"context"
-	"fmt"
 	"html/template"
 	"net/http"
 	"path"
-	"reflect"
 	"regexp"
 	"sync"
 
@@ -25,14 +23,12 @@ import (
 	v1 "github.com/prometheus/prometheus/web/api/v1"
 	"github.com/weaveworks/common/instrument"
 	"github.com/weaveworks/common/middleware"
-	"gopkg.in/yaml.v2"
 
 	"github.com/cortexproject/cortex/pkg/chunk/purger"
 	"github.com/cortexproject/cortex/pkg/distributor"
 	"github.com/cortexproject/cortex/pkg/querier"
 	"github.com/cortexproject/cortex/pkg/querier/stats"
 	"github.com/cortexproject/cortex/pkg/util"
-	"github.com/cortexproject/cortex/pkg/util/runtimeconfig"
 )
 
 const (
@@ -117,95 +113,24 @@ func indexHandler(httpPathPrefix string, content *IndexPageContent) http.Handler
 	}
 }
 
-func yamlMarshalUnmarshal(in interface{}) (map[interface{}]interface{}, error) {
-	yamlBytes, err := yaml.Marshal(in)
-	if err != nil {
-		return nil, err
-	}
-
-	object := make(map[interface{}]interface{})
-	if err := yaml.Unmarshal(yamlBytes, object); err != nil {
-		return nil, err
-	}
-
-	return object, nil
-}
-
-func diffConfig(defaultConfig, actualConfig map[interface{}]interface{}) (map[interface{}]interface{}, error) {
-	output := make(map[interface{}]interface{})
-
-	for key, value := range actualConfig {
-
-		defaultValue, ok := defaultConfig[key]
-		if !ok {
-			output[key] = value
-			continue
-		}
-
-		switch v := value.(type) {
-		case int:
-			defaultV, ok := defaultValue.(int)
-			if !ok || defaultV != v {
-				output[key] = v
-			}
-		case string:
-			defaultV, ok := defaultValue.(string)
-			if !ok || defaultV != v {
-				output[key] = v
-			}
-		case bool:
-			defaultV, ok := defaultValue.(bool)
-			if !ok || defaultV != v {
-				output[key] = v
-			}
-		case []interface{}:
-			defaultV, ok := defaultValue.([]interface{})
-			if !ok || !reflect.DeepEqual(defaultV, v) {
-				output[key] = v
-			}
-		case float64:
-			defaultV, ok := defaultValue.(float64)
-			if !ok || !reflect.DeepEqual(defaultV, v) {
-				output[key] = v
-			}
-		case map[interface{}]interface{}:
-			defaultV, ok := defaultValue.(map[interface{}]interface{})
-			if !ok {
-				output[key] = value
-			}
-			diff, err := diffConfig(defaultV, v)
-			if err != nil {
-				return nil, err
-			}
-			if len(diff) > 0 {
-				output[key] = diff
-			}
-		default:
-			return nil, fmt.Errorf("unsupported type %T", v)
-		}
-	}
-
-	return output, nil
-}
-
 func configHandler(actualCfg interface{}, defaultCfg interface{}) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		var output interface{}
 		switch r.URL.Query().Get("mode") {
 		case "diff":
-			defaultCfgObj, err := yamlMarshalUnmarshal(defaultCfg)
+			defaultCfgObj, err := util.YAMLMarshalUnmarshal(defaultCfg)
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
 			}
 
-			actualCfgObj, err := yamlMarshalUnmarshal(actualCfg)
+			actualCfgObj, err := util.YAMLMarshalUnmarshal(actualCfg)
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
 			}
 
-			diff, err := diffConfig(defaultCfgObj, actualCfgObj)
+			diff, err := util.DiffConfig(defaultCfgObj, actualCfgObj)
 			if err != nil {
 				http.Error(w, err.Error(), http.StatusInternalServerError)
 				return
@@ -222,17 +147,6 @@ func configHandler(actualCfg interface{}, defaultCfg interface{}) http.HandlerFu
 	}
 }
 
-func runtimeConfigHandler(runtimeCfgManager *runtimeconfig.Manager) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		runtimeConfig := runtimeCfgManager.GetConfig()
-		if runtimeConfig == nil {
-			util.WriteTextResponse(w, "runtime config file doesn't exist")
-			return
-		}
-		util.WriteYAMLResponse(w, runtimeConfig)
-	}
-}
-
 // NewQuerierHandler returns a HTTP handler that can be used by the querier service to
 // either register with the frontend worker query processor or with the external HTTP
 // server to fulfill the Prometheus query API.

pkg/cortex/modules.go

@@ -159,7 +159,7 @@ func (t *Cortex) initRuntimeConfig() (services.Service, error) {
 
 	serv, err := runtimeconfig.NewRuntimeConfigManager(t.Cfg.RuntimeConfig, prometheus.DefaultRegisterer)
 	t.RuntimeConfig = serv
-	t.API.RegisterRuntimeConfig(t.RuntimeConfig)
+	t.API.RegisterRuntimeConfig(runtimeConfigHandler(t.RuntimeConfig, t.Cfg.LimitsConfig))
 	return serv, err
 }
 

pkg/cortex/runtime_config.go

@@ -3,10 +3,12 @@ package cortex
 import (
 	"errors"
 	"io"
+	"net/http"
 
 	"gopkg.in/yaml.v2"
 
 	"github.com/cortexproject/cortex/pkg/ring/kv"
+	"github.com/cortexproject/cortex/pkg/util"
 	"github.com/cortexproject/cortex/pkg/util/runtimeconfig"
 	"github.com/cortexproject/cortex/pkg/util/validation"
 )
@@ -83,3 +85,48 @@ func multiClientRuntimeConfigChannel(manager *runtimeconfig.Manager) func() <-ch
 		return outCh
 	}
 }
+func runtimeConfigHandler(runtimeCfgManager *runtimeconfig.Manager, defaultLimits validation.Limits) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		cfg, ok := runtimeCfgManager.GetConfig().(*runtimeConfigValues)
+		if !ok || cfg == nil {
+			util.WriteTextResponse(w, "runtime config file doesn't exist")
+			return
+		}
+
+		var output interface{}
+		switch r.URL.Query().Get("mode") {
+		case "diff":
+			// Default runtime config is just empty struct, but to make diff work,
+			// we set defaultLimits for every tenant that exists in runtime config.
+			defaultCfg := runtimeConfigValues{}
+			defaultCfg.TenantLimits = map[string]*validation.Limits{}
+			for k, v := range cfg.TenantLimits {
+				if v != nil {
+					defaultCfg.TenantLimits[k] = &defaultLimits
+				}
+			}
+
+			cfgYaml, err := util.YAMLMarshalUnmarshal(cfg)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			defaultCfgYaml, err := util.YAMLMarshalUnmarshal(defaultCfg)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+			output, err = util.DiffConfig(defaultCfgYaml, cfgYaml)
+			if err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+
+		default:
+			output = cfg
+		}
+		util.WriteYAMLResponse(w, output)
+	}
+}

pkg/util/config.go

@@ -0,0 +1,68 @@
+package util
+
+import (
+	"fmt"
+	"reflect"
+)
+
+// DiffConfig utility function that returns the diff between two config map objects
+func DiffConfig(defaultConfig, actualConfig map[interface{}]interface{}) (map[interface{}]interface{}, error) {
+	output := make(map[interface{}]interface{})
+
+	for key, value := range actualConfig {
+
+		defaultValue, ok := defaultConfig[key]
+		if !ok {
+			output[key] = value
+			continue
+		}
+
+		switch v := value.(type) {
+		case int:
+			defaultV, ok := defaultValue.(int)
+			if !ok || defaultV != v {
+				output[key] = v
+			}
+		case string:
+			defaultV, ok := defaultValue.(string)
+			if !ok || defaultV != v {
+				output[key] = v
+			}
+		case bool:
+			defaultV, ok := defaultValue.(bool)
+			if !ok || defaultV != v {
+				output[key] = v
+			}
+		case []interface{}:
+			defaultV, ok := defaultValue.([]interface{})
+			if !ok || !reflect.DeepEqual(defaultV, v) {
+				output[key] = v
+			}
+		case float64:
+			defaultV, ok := defaultValue.(float64)
+			if !ok || !reflect.DeepEqual(defaultV, v) {
+				output[key] = v
+			}
+		case nil:
+			if defaultValue != nil {
+				output[key] = v
+			}
+		case map[interface{}]interface{}:
+			defaultV, ok := defaultValue.(map[interface{}]interface{})
+			if !ok {
+				output[key] = value
+			}
+			diff, err := DiffConfig(defaultV, v)
+			if err != nil {
+				return nil, err
+			}
+			if len(diff) > 0 {
+				output[key] = diff
+			}
+		default:
+			return nil, fmt.Errorf("unsupported type %T", v)
+		}
+	}
+
+	return output, nil
+}

pkg/util/yaml.go

@@ -0,0 +1,19 @@
+package util
+
+import "gopkg.in/yaml.v2"
+
+// YAMLMarshalUnmarshal utility function that converts a YAML interface in a map
+// doing marshal and unmarshal of the parameter
+func YAMLMarshalUnmarshal(in interface{}) (map[interface{}]interface{}, error) {
+	yamlBytes, err := yaml.Marshal(in)
+	if err != nil {
+		return nil, err
+	}
+
+	object := make(map[interface{}]interface{})
+	if err := yaml.Unmarshal(yamlBytes, object); err != nil {
+		return nil, err
+	}
+
+	return object, nil
+}