Add an ability to load an arbitrary list of Cortex modules

CHANGELOG.md

@@ -48,6 +48,7 @@
 * [CHANGE] Renamed `-redis.enable-tls` CLI flag to `-redis.tls-enabled`, and its respective YAML config option from `enable_tls` to `tls_enabled`. #3298
 * [FEATURE] Added support for shuffle-sharding queriers in the query-frontend. When configured (`-frontend.max-queriers-per-tenant` globally, or using per-tenant limit `max_queriers_per_tenant`), each tenants's requests will be handled by different set of queriers. #3113 #3257
 * [FEATURE] Query-frontend: added `compression` config to support results cache with compression. #3217
+* [ENHANCEMENT] Allow to specify multiple comma-separated Cortex services to `-target` CLI option (or its respective YAML config option). For example, `-target=all,compactor` can be used to start Cortex single-binary with compactor as well. #3275
 * [ENHANCEMENT] Expose additional HTTP configs for the S3 backend client. New flag are listed below: #3244
   - `-blocks-storage.s3.http.idle-conn-timeout`
   - `-blocks-storage.s3.http.response-header-timeout`

cmd/cortex/main.go

@@ -146,8 +146,13 @@ func main() {
 	// In testing mode skip JAEGER setup to avoid panic due to
 	// "duplicate metrics collector registration attempted"
 	if !testMode {
+		name := "cortex"
+		if len(cfg.Target) == 1 {
+			name += "-" + cfg.Target[0]
+		}
+
 		// Setting the environment variable JAEGER_AGENT_HOST enables tracing.
-		if trace, err := tracing.NewFromEnv("cortex-" + cfg.Target); err != nil {
+		if trace, err := tracing.NewFromEnv(name); err != nil {
 			level.Error(util.Logger).Log("msg", "Failed to setup tracing", "err", err.Error())
 		} else {
 			defer trace.Close()

docs/configuration/config-file-reference.md

@@ -52,8 +52,10 @@ Where default_value is the value to use if the environment variable is undefined
 ### Supported contents and default values of the config file
 
 ```yaml
-# The Cortex module to run. Use "-modules" command line flag to get a list of
-# available modules, and to see which modules are included in "All".
+# Comma-separated list of Cortex modules to load. The alias 'all' can be used in
+# the list to load a number of core modules and will enable single-binary mode.
+# Use '-modules' command line flag to get a list of available modules, and to
+# see which modules are included in 'all'.
 # CLI flag: -target
 [target: <string> | default = "all"]
 

pkg/cortex/cortex.go

@@ -71,10 +71,10 @@ import (
 
 // Config is the root config for Cortex.
 type Config struct {
-	Target      string `yaml:"target"`
-	AuthEnabled bool   `yaml:"auth_enabled"`
-	PrintConfig bool   `yaml:"-"`
-	HTTPPrefix  string `yaml:"http_prefix"`
+	Target      flagext.StringSliceCSV `yaml:"target"`
+	AuthEnabled bool                   `yaml:"auth_enabled"`
+	PrintConfig bool                   `yaml:"-"`
+	HTTPPrefix  string                 `yaml:"http_prefix"`
 
 	API            api.Config               `yaml:"api"`
 	Server         server.Config            `yaml:"server"`
@@ -109,7 +109,14 @@ type Config struct {
 func (c *Config) RegisterFlags(f *flag.FlagSet) {
 	c.Server.MetricsNamespace = "cortex"
 	c.Server.ExcludeRequestInLog = true
-	f.StringVar(&c.Target, "target", All, "The Cortex module to run. Use \"-modules\" command line flag to get a list of available modules, and to see which modules are included in \"All\".")
+
+	// Set the default module list to 'all'
+	c.Target = []string{All}
+
+	f.Var(&c.Target, "target", "Comma-separated list of Cortex modules to load. "+
+		"The alias 'all' can be used in the list to load a number of core modules and will enable single-binary mode. "+
+		"Use '-modules' command line flag to get a list of available modules, and to see which modules are included in 'all'.")
+
 	f.BoolVar(&c.AuthEnabled, "auth.enabled", true, "Set to false to disable auth.")
 	f.BoolVar(&c.PrintConfig, "print.config", false, "Print the config and exit.")
 	f.StringVar(&c.HTTPPrefix, "http.prefix", "/api/prom", "HTTP path prefix for Cortex API.")
@@ -203,6 +210,10 @@ func (c *Config) Validate(log log.Logger) error {
 	return nil
 }
 
+func (c *Config) isModuleEnabled(m string) bool {
+	return util.StringsContain(c.Target, m)
+}
+
 // validateYAMLEmptyNodes ensure that no empty node has been specified in the YAML config file.
 // When an empty node is defined in YAML, the YAML parser sets the whole struct to its zero value
 // and so we loose all default values. It's very difficult to detect this case for the user, so we
@@ -307,16 +318,18 @@ func (t *Cortex) setupThanosTracing() {
 
 // Run starts Cortex running, and blocks until a Cortex stops.
 func (t *Cortex) Run() error {
-	if !t.ModuleManager.IsUserVisibleModule(t.Cfg.Target) {
-		level.Warn(util.Logger).Log("msg", "selected target is an internal module, is this intended?", "target", t.Cfg.Target)
+	for _, module := range t.Cfg.Target {
+		if !t.ModuleManager.IsUserVisibleModule(module) {
+			level.Warn(util.Logger).Log("msg", "selected target is an internal module, is this intended?", "target", module)
+		}
 	}
 
-	serviceMap, err := t.ModuleManager.InitModuleServices(t.Cfg.Target)
+	var err error
+	t.ServiceMap, err = t.ModuleManager.InitModuleServices(t.Cfg.Target...)
 	if err != nil {
 		return err
 	}
 
-	t.ServiceMap = serviceMap
 	t.API.RegisterServiceMapHandler(http.HandlerFunc(t.servicesHandler))
 
 	// get all services, create service manager and tell it to start

pkg/cortex/cortex_test.go

@@ -68,13 +68,14 @@ func TestCortex(t *testing.T) {
 				},
 			},
 		},
-		Target: All,
+
+		Target: []string{All, Compactor},
 	}
 
 	c, err := New(cfg)
 	require.NoError(t, err)
 
-	serviceMap, err := c.ModuleManager.InitModuleServices(c.Cfg.Target)
+	serviceMap, err := c.ModuleManager.InitModuleServices(cfg.Target...)
 	require.NoError(t, err)
 	require.NotNil(t, serviceMap)
 
@@ -88,4 +89,7 @@ func TestCortex(t *testing.T) {
 	require.NotNil(t, serviceMap[IngesterService])
 	require.NotNil(t, serviceMap[Ring])
 	require.NotNil(t, serviceMap[DistributorService])
+
+	// check that compactor is configured which is not part of Target=All
+	require.NotNil(t, serviceMap[Compactor])
 }

pkg/cortex/modules.go

@@ -135,7 +135,7 @@ func (t *Cortex) initRuntimeConfig() (services.Service, error) {
 		t.Cfg.LimitsConfig.RulerEvaluationDelay = t.Cfg.Ruler.EvaluationDelay
 
 		// No need to report if this field isn't going to be used.
-		if t.Cfg.Target == All || t.Cfg.Target == Ruler {
+		if t.Cfg.isModuleEnabled(Ruler) || t.Cfg.isModuleEnabled(All) {
 			flagext.DeprecatedFlagsUsed.Inc()
 			level.Warn(util.Logger).Log("msg", "Using DEPRECATED YAML config field ruler.evaluation_delay_duration, please use limits.ruler_evaluation_delay_duration instead.")
 		}
@@ -173,7 +173,7 @@ func (t *Cortex) initDistributorService() (serv services.Service, err error) {
 	// Check whether the distributor can join the distributors ring, which is
 	// whenever it's not running as an internal dependency (ie. querier or
 	// ruler's dependency)
-	canJoinDistributorsRing := (t.Cfg.Target == All || t.Cfg.Target == Distributor)
+	canJoinDistributorsRing := t.Cfg.isModuleEnabled(Distributor) || t.Cfg.isModuleEnabled(All)
 
 	t.Distributor, err = distributor.New(t.Cfg.Distributor, t.Cfg.IngesterClient, t.Overrides, t.Ring, canJoinDistributorsRing, prometheus.DefaultRegisterer)
 	if err != nil {
@@ -222,12 +222,12 @@ func (t *Cortex) initQuerier() (serv services.Service, err error) {
 	}, []string{"method", "route"})
 
 	// if we are not configured for single binary mode then the querier needs to register its paths externally
-	registerExternally := t.Cfg.Target != All
+	registerExternally := !t.Cfg.isModuleEnabled(All)
 	handler := t.API.RegisterQuerier(queryable, engine, t.Distributor, registerExternally, t.TombstonesLoader, querierRequestDuration, receivedMessageSize, sentMessageSize, inflightRequests)
 
 	// single binary mode requires a properly configured worker.  if the operator did not attempt to configure the
 	//  worker we will attempt an automatic configuration here
-	if t.Cfg.Worker.Address == "" && t.Cfg.Target == All {
+	if t.Cfg.Worker.Address == "" && t.Cfg.isModuleEnabled(All) {
 		address := fmt.Sprintf("127.0.0.1:%d", t.Cfg.Server.GRPCListenPort)
 		level.Warn(util.Logger).Log("msg", "Worker address is empty in single binary mode.  Attempting automatic worker configuration.  If queries are unresponsive consider configuring the worker explicitly.", "address", address)
 		t.Cfg.Worker.Address = address
@@ -298,7 +298,7 @@ func initQueryableForEngine(engine string, cfg Config, chunkStore chunk.Store, l
 	case storage.StorageEngineBlocks:
 		// When running in single binary, if the blocks sharding is disabled and no custom
 		// store-gateway address has been configured, we can set it to the running process.
-		if cfg.Target == All && !cfg.StoreGateway.ShardingEnabled && cfg.Querier.StoreGatewayAddresses == "" {
+		if cfg.isModuleEnabled(All) && !cfg.StoreGateway.ShardingEnabled && cfg.Querier.StoreGatewayAddresses == "" {
 			cfg.Querier.StoreGatewayAddresses = fmt.Sprintf("127.0.0.1:%d", cfg.Server.GRPCListenPort)
 		}
 
@@ -510,13 +510,12 @@ func (t *Cortex) initRulerStorage() (serv services.Service, err error) {
 	// unfortunately there is no way to generate a "default" config and compare default against actual
 	// to determine if it's unconfigured.  the following check, however, correctly tests this.
 	// Single binary integration tests will break if this ever drifts
-	if t.Cfg.Target == All && t.Cfg.Ruler.StoreConfig.IsDefaults() {
+	if t.Cfg.isModuleEnabled(All) && t.Cfg.Ruler.StoreConfig.IsDefaults() {
 		level.Info(util.Logger).Log("msg", "RulerStorage is not configured in single binary mode and will not be started.")
 		return
 	}
 
 	t.RulerStorage, err = ruler.NewRuleStorage(t.Cfg.Ruler.StoreConfig, rules.FileLoader{})
-
 	return
 }
 
@@ -574,7 +573,7 @@ func (t *Cortex) initAlertManager() (serv services.Service, err error) {
 		return
 	}
 
-	t.API.RegisterAlertmanager(t.Alertmanager, t.Cfg.Target == AlertManager, t.Cfg.Alertmanager.EnableAPI)
+	t.API.RegisterAlertmanager(t.Alertmanager, t.Cfg.isModuleEnabled(AlertManager), t.Cfg.Alertmanager.EnableAPI)
 	return t.Alertmanager, nil
 }
 
@@ -593,7 +592,7 @@ func (t *Cortex) initCompactor() (serv services.Service, err error) {
 
 func (t *Cortex) initStoreGateway() (serv services.Service, err error) {
 	if t.Cfg.Storage.Engine != storage.StorageEngineBlocks {
-		if t.Cfg.Target != All {
+		if !t.Cfg.isModuleEnabled(All) {
 			return nil, fmt.Errorf("storage engine must be set to blocks to enable the store-gateway")
 		}
 		return nil, nil

pkg/cortex/server_service.go

@@ -54,6 +54,7 @@ func NewServerService(serv *server.Server, servicesToWaitFor func() []services.S
 	return services.NewBasicService(nil, runFn, stoppingFn)
 }
 
+// DisableSignalHandling puts a dummy signal handler
 func DisableSignalHandling(config *server.Config) {
 	config.SignalHandler = make(ignoreSignalHandler)
 }

pkg/util/flagext/stringslicecsv.go

@@ -0,0 +1,33 @@
+package flagext
+
+import "strings"
+
+// StringSliceCSV is a slice of strings that is parsed from a comma-separated string
+// It implements flag.Value and yaml Marshalers
+type StringSliceCSV []string
+
+// String implements flag.Value
+func (v StringSliceCSV) String() string {
+	return strings.Join(v, ",")
+}
+
+// Set implements flag.Value
+func (v *StringSliceCSV) Set(s string) error {
+	*v = strings.Split(s, ",")
+	return nil
+}
+
+// UnmarshalYAML implements yaml.Unmarshaler.
+func (v *StringSliceCSV) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var s string
+	if err := unmarshal(&s); err != nil {
+		return err
+	}
+
+	return v.Set(s)
+}
+
+// MarshalYAML implements yaml.Marshaler.
+func (v StringSliceCSV) MarshalYAML() (interface{}, error) {
+	return v.String(), nil
+}

pkg/util/flagext/stringslicecsv_test.go

@@ -0,0 +1,34 @@
+package flagext
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/yaml.v2"
+)
+
+func Test_StringSliceCSV(t *testing.T) {
+	type TestStruct struct {
+		CSV StringSliceCSV `yaml:"csv"`
+	}
+
+	var testStruct TestStruct
+	s := "a,b,c,d"
+	assert.Nil(t, testStruct.CSV.Set(s))
+
+	assert.Equal(t, []string{"a", "b", "c", "d"}, []string(testStruct.CSV))
+	assert.Equal(t, s, testStruct.CSV.String())
+
+	expected := []byte(`csv: a,b,c,d
+`)
+
+	actual, err := yaml.Marshal(testStruct)
+	assert.Nil(t, err)
+	assert.Equal(t, expected, actual)
+
+	var testStruct2 TestStruct
+
+	err = yaml.Unmarshal(expected, &testStruct2)
+	assert.Nil(t, err)
+	assert.Equal(t, testStruct, testStruct2)
+}

pkg/util/modules/modules.go

@@ -64,29 +64,45 @@ func (m *Manager) AddDependency(name string, dependsOn ...string) error {
 	return nil
 }
 
-// InitModuleServices initialises the target module by initialising all its dependencies
+// InitModuleServices initialises given modules by initialising all their dependencies
 // in the right order. Modules are wrapped in such a way that they start after their
 // dependencies have been started and stop before their dependencies are stopped.
-func (m *Manager) InitModuleServices(target string) (map[string]services.Service, error) {
-	if _, ok := m.modules[target]; !ok {
-		return nil, fmt.Errorf("unrecognised module name: %s", target)
+func (m *Manager) InitModuleServices(modules ...string) (map[string]services.Service, error) {
+	servicesMap := map[string]services.Service{}
+	initMap := map[string]bool{}
+
+	for _, module := range modules {
+		if err := m.initModule(module, initMap, servicesMap); err != nil {
+			return nil, err
+		}
 	}
 
-	servicesMap := map[string]services.Service{}
+	return servicesMap, nil
+}
+
+func (m *Manager) initModule(name string, initMap map[string]bool, servicesMap map[string]services.Service) error {
+	if _, ok := m.modules[name]; !ok {
+		return fmt.Errorf("unrecognised module name: %s", name)
+	}
 
 	// initialize all of our dependencies first
-	deps := m.orderedDeps(target)
-	deps = append(deps, target) // lastly, initialize the requested module
+	deps := m.orderedDeps(name)
+	deps = append(deps, name) // lastly, initialize the requested module
 
 	for ix, n := range deps {
+		// Skip already initialized modules
+		if initMap[n] {
+			continue
+		}
+
 		mod := m.modules[n]
 
 		var serv services.Service
 
 		if mod.initFn != nil {
 			s, err := mod.initFn()
 			if err != nil {
-				return nil, errors.Wrap(err, fmt.Sprintf("error initialising module: %s", n))
+				return errors.Wrap(err, fmt.Sprintf("error initialising module: %s", n))
 			}
 
 			if s != nil {
@@ -99,9 +115,11 @@ func (m *Manager) InitModuleServices(target string) (map[string]services.Service
 		if serv != nil {
 			servicesMap[n] = serv
 		}
+
+		initMap[n] = true
 	}
 
-	return servicesMap, nil
+	return nil
 }
 
 // UserVisibleModuleNames gets list of module names that are