chore: replace ifrit with stdlib runner

# Issue
`ifrit` (`github.com/tedsuo/ifrit`) is not maintained.

# Fix
Replace `ifrit` with a small internal `helpers/runner` package built on Go stdlib
(`context`, `net/http`, `os/signal`). The package provides the same primitives
that `ifrit` did: a `Runner` interface, a `RunFunc` adapter, named `Member` structs,
and `StartOrdered` for ordered startup with LIFO graceful shutdown triggered by
`SIGINT`/`SIGTERM` or context cancellation.

A companion `helpers/runner/testrunner` package replaces `ginkgomon_v2` for tests,
offering `Invoke`/`Interrupt`/`Kill` helpers for in-process runners and a
`CmdRunner` that starts external binaries and waits for a configurable start-check
string in their combined stdout+stderr before signalling ready.

All five Go services (`api`, `eventgenerator`, `scalingengine`, `metricsforwarder`,
`operator`) and the shared `startup`, `sync`, and `helpers` packages are updated
accordingly. `ifrit` is removed from `go.mod`.

Author: silvestre

CLAUDE.md

@@ -57,6 +57,17 @@ make generate-fakes          # Generate test mocks with Counterfeiter
 make generate-openapi-generated-clients-and-servers  # Generate OpenAPI clients/servers
 ```
 
+### Verifying Bigger Changes
+
+Always run these two steps to verify bigger changes (refactors, dependency replacements, new packages):
+
+```bash
+make clean check             # Clean, lint, build, and run all unit tests (no DB needed)
+make integration             # Run integration tests (requires PostgreSQL: make start-db first)
+```
+
+`make clean check` is the primary gate — it runs a full clean build plus all non-DB unit tests with the race detector. `make integration` catches DB-dependent behaviour and inter-service contracts.
+
 ### Deployment
 ```bash
 make mta-deploy              # Deploy to Cloud Foundry using MTA

api/brokerserver/broker_server.go

@@ -14,12 +14,12 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/healthendpoint"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/handlers"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/routes"
 	"code.cloudfoundry.org/brokerapi/v13"
 	"code.cloudfoundry.org/brokerapi/v13/domain"
 	"code.cloudfoundry.org/lager/v3"
 	"github.com/go-chi/chi/v5"
-	"github.com/tedsuo/ifrit"
 	"golang.org/x/crypto/bcrypt"
 )
 
@@ -63,7 +63,7 @@ func (am *AuthMiddleware) authenticate(r *http.Request) bool {
 }
 
 type BrokerServer interface {
-	CreateServer() (ifrit.Runner, error)
+	CreateServer() (runner.Runner, error)
 	GetRouter() (*chi.Mux, error)
 }
 
@@ -89,7 +89,7 @@ func NewBrokerServer(logger lager.Logger, conf *config.Config, bindingDB db.Bind
 	}
 }
 
-func (s *brokerServer) CreateServer() (ifrit.Runner, error) {
+func (s *brokerServer) CreateServer() (runner.Runner, error) {
 	router, err := s.GetRouter()
 	if err != nil {
 		return nil, err

api/brokerserver/broker_server_suite_test.go

@@ -10,16 +10,15 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers"
 	"code.cloudfoundry.org/brokerapi/v13/domain"
 
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner/testrunner"
+
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/api/brokerserver"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/api/config"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/fakes"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/routes"
 
 	"github.com/onsi/gomega/ghttp"
 
-	"github.com/tedsuo/ifrit"
-	"github.com/tedsuo/ifrit/ginkgomon_v2"
-
 	"code.cloudfoundry.org/lager/v3"
 
 	. "github.com/onsi/ginkgo/v2"
@@ -41,7 +40,7 @@ const (
 )
 
 var (
-	serverProcess     ifrit.Process
+	serverProcess     *testrunner.Process
 	serverUrl         *url.URL
 	httpClient        *http.Client
 	conf              *config.Config
@@ -153,7 +152,7 @@ var _ = BeforeSuite(func() {
 	serverUrl, err = url.Parse("http://localhost:" + strconv.Itoa(port))
 	Expect(err).NotTo(HaveOccurred())
 
-	serverProcess = ginkgomon_v2.Invoke(httpServer)
+	serverProcess = testrunner.Invoke(httpServer)
 
 	httpClient = &http.Client{}
 
@@ -179,5 +178,5 @@ var _ = AfterSuite(func() {
 	for _, server := range servers {
 		server.Close()
 	}
-	ginkgomon_v2.Interrupt(serverProcess)
+	serverProcess.Interrupt()
 })

api/cmd/api/main.go

@@ -11,11 +11,11 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/db"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/db/sqldb"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/healthendpoint"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/ratelimiter"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/startup"
 
 	"code.cloudfoundry.org/lager/v3"
-	"github.com/tedsuo/ifrit/grouper"
 )
 
 func main() {
@@ -72,13 +72,12 @@ func main() {
 	unifiedServer, err := publicApiServer.CreateCFServer()
 	startup.ExitOnError(err, logger, "failed to create public api http server")
 
-	members := grouper.Members{}
-	members = append(members,
-		grouper.Member{Name: "public_api_http_server", Runner: mtlsServer},
-		grouper.Member{Name: "broker", Runner: brokerHttpServer},
-		grouper.Member{Name: "health_server", Runner: healthServer},
-		grouper.Member{Name: "unified_server", Runner: unifiedServer},
-	)
+	members := []runner.Member{
+		{Name: "public_api_http_server", Runner: mtlsServer},
+		{Name: "broker", Runner: brokerHttpServer},
+		{Name: "health_server", Runner: healthServer},
+		{Name: "unified_server", Runner: unifiedServer},
+	}
 
 	err = startup.StartServices(logger, members)
 	if err != nil {

api/publicapiserver/public_api_server.go

@@ -16,13 +16,13 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/cf"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/db"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/healthendpoint"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/ratelimiter"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/routes"
 
 	"code.cloudfoundry.org/lager/v3"
 	"github.com/gorilla/mux"
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/tedsuo/ifrit"
 )
 
 type VarsFunc func(w http.ResponseWriter, r *http.Request, vars map[string]string)
@@ -70,7 +70,7 @@ func NewPublicApiServer(logger lager.Logger, conf *config.Config, policyDB db.Po
 	}
 }
 
-func (s *PublicApiServer) CreateHealthServer() (ifrit.Runner, error) {
+func (s *PublicApiServer) CreateHealthServer() (runner.Runner, error) {
 	if err := s.setupHealthRouter(); err != nil {
 		return nil, err
 	}
@@ -89,7 +89,7 @@ func (s *PublicApiServer) setupBrokerRouter() error {
 	return nil
 }
 
-func (s *PublicApiServer) CreateCFServer() (ifrit.Runner, error) {
+func (s *PublicApiServer) CreateCFServer() (runner.Runner, error) {
 	if err := s.setupBrokerRouter(); err != nil {
 		return nil, err
 	}
@@ -107,7 +107,7 @@ func (s *PublicApiServer) CreateCFServer() (ifrit.Runner, error) {
 	return helpers.NewHTTPServer(s.logger.Session("CfServer"), s.conf.CFServer, r)
 }
 
-func (s *PublicApiServer) CreateMtlsServer() (ifrit.Runner, error) {
+func (s *PublicApiServer) CreateMtlsServer() (runner.Runner, error) {
 	if err := s.setupApiRoutes(); err != nil {
 		return nil, err
 	}

api/publicapiserver/public_api_server_test.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/api/publicapiserver"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner/testrunner"
 	internalscalinghistory "code.cloudfoundry.org/app-autoscaler/src/autoscaler/scalingengine/apis/scalinghistory"
 	"code.cloudfoundry.org/lager/v3/lagertest"
 
@@ -15,7 +16,6 @@ import (
 	"github.com/go-chi/chi/v5"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
-	"github.com/tedsuo/ifrit/ginkgomon_v2"
 )
 
 var _ = Describe("PublicApiServer", func() {
@@ -82,7 +82,7 @@ var _ = Describe("PublicApiServer", func() {
 	})
 
 	AfterEach(func() {
-		ginkgomon_v2.Interrupt(serverProcess)
+		serverProcess.Interrupt()
 	})
 
 	Describe("CreateMtlsServer", func() {
@@ -103,7 +103,7 @@ var _ = Describe("PublicApiServer", func() {
 
 			httpServer, err := publicApiServer.CreateMtlsServer()
 			Expect(err).NotTo(HaveOccurred())
-			serverProcess = ginkgomon_v2.Invoke(httpServer)
+			serverProcess = testrunner.Invoke(httpServer)
 		})
 
 		Context("when calling health endpoint", func() {
@@ -464,7 +464,7 @@ var _ = Describe("PublicApiServer", func() {
 
 			httpServer, err := publicApiServer.CreateHealthServer()
 			Expect(err).NotTo(HaveOccurred())
-			serverProcess = ginkgomon_v2.Invoke(httpServer)
+			serverProcess = testrunner.Invoke(httpServer)
 		})
 
 		It("should succeed", func() {
@@ -491,7 +491,7 @@ var _ = Describe("PublicApiServer", func() {
 
 			httpServer, err := publicApiServer.CreateCFServer()
 			Expect(err).NotTo(HaveOccurred())
-			serverProcess = ginkgomon_v2.Invoke(httpServer)
+			serverProcess = testrunner.Invoke(httpServer)
 		})
 
 		Context("when calling info endpoint", func() {

api/publicapiserver/publicapiserver_suite_test.go

@@ -15,13 +15,13 @@ import (
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 	"github.com/onsi/gomega/ghttp"
-	"github.com/tedsuo/ifrit"
 
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/api"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/api/config"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/cf"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/fakes"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner/testrunner"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/models"
 )
 
@@ -41,7 +41,7 @@ const (
 )
 
 var (
-	serverProcess ifrit.Process
+	serverProcess *testrunner.Process
 	serverUrl     *url.URL
 	cfServerUrl   *url.URL
 	healthUrl     *url.URL

eventgenerator/aggregator/metric_poller_test.go

@@ -72,10 +72,7 @@ var _ = Describe("MetricPoller", func() {
 		It("logs an error", func() {
 			//TODO this should be a prometheus counter not a log statement check
 
-			// Subsequently disabling linting, because there is nothing wrong with using whitespaces
-			// to separate two multiplicands from the operation-symbol.
-			// (Actually it is more readable.)
-			Eventually(logger.Buffer, 10 * time.Second).Should(Say("retrieveMetric Failed")) //nolint
+			Eventually(logger.Buffer, 10*time.Second).Should(Say("retrieveMetric Failed"))
 
 		})
 

eventgenerator/cmd/eventgenerator/main.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"os"
+	"context"
 
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/db"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/eventgenerator/aggregator"
@@ -12,14 +12,14 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/healthendpoint"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/auth"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/models"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/startup"
 	"github.com/prometheus/client_golang/prometheus"
 	circuit "github.com/rubyist/circuitbreaker"
 
 	"code.cloudfoundry.org/clock"
 	"code.cloudfoundry.org/lager/v3"
-	"github.com/tedsuo/ifrit"
 )
 
 func main() {
@@ -65,23 +65,23 @@ func main() {
 	anAggregator, err := aggregator.NewAggregator(logger, clock, conf.Aggregator.AggregatorExecuteInterval, conf.Aggregator.SaveInterval, appMonitorsChan, appManager.GetPolicies, appManager.SaveMetricToCache, conf.DefaultStatWindowSecs, appMetricChan, appMetricDB.DB)
 	startup.ExitOnError(err, logger, "failed to create Aggregator")
 
-	eventGenerator := ifrit.RunFunc(runFunc(appManager, evaluators, evaluationManager, metricPollers, anAggregator))
+	eventGenerator := runner.RunFunc(runFunc(appManager, evaluators, evaluationManager, metricPollers, anAggregator))
 
 	// Server setup
 	eventgeneratorServer := server.NewServer(logger.Session("http_server"), conf, appMetricDB.DB, policyDb.DB, appManager.QueryAppMetrics, httpStatusCollector)
 	xm := auth.NewXfccAuthMiddleware(logger, conf.CFServer.XFCC)
 
 	// Start services
 	startup.StartService(logger,
-		startup.Server("eventGenerator", func() (ifrit.Runner, error) { return eventGenerator, nil }),
+		startup.Server("eventGenerator", func() (runner.Runner, error) { return eventGenerator, nil }),
 		startup.Server("https_server", eventgeneratorServer.CreateMtlsServer),
 		startup.Server("health_server", eventgeneratorServer.CreateHealthServer),
-		startup.Server("cf_server", func() (ifrit.Runner, error) { return eventgeneratorServer.CreateCFServer(xm) }),
+		startup.Server("cf_server", func() (runner.Runner, error) { return eventgeneratorServer.CreateCFServer(xm) }),
 	)
 }
 
-func runFunc(appManager *aggregator.AppManager, evaluators []*generator.Evaluator, evaluationManager *generator.AppEvaluationManager, metricPollers []*aggregator.MetricPoller, anAggregator *aggregator.Aggregator) func(signals <-chan os.Signal, ready chan<- struct{}) error {
-	return func(signals <-chan os.Signal, ready chan<- struct{}) error {
+func runFunc(appManager *aggregator.AppManager, evaluators []*generator.Evaluator, evaluationManager *generator.AppEvaluationManager, metricPollers []*aggregator.MetricPoller, anAggregator *aggregator.Aggregator) func(ctx context.Context, ready chan<- struct{}) error {
+	return func(ctx context.Context, ready chan<- struct{}) error {
 		appManager.Start()
 
 		for _, evaluator := range evaluators {
@@ -96,7 +96,7 @@ func runFunc(appManager *aggregator.AppManager, evaluators []*generator.Evaluato
 
 		close(ready)
 
-		<-signals
+		<-ctx.Done()
 		anAggregator.Stop()
 		evaluationManager.Stop()
 		appManager.Stop()

eventgenerator/server/server.go

@@ -9,6 +9,7 @@ import (
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/eventgenerator/aggregator"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers"
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/auth"
+	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/helpers/runner"
 	"go.opentelemetry.io/contrib/instrumentation/github.com/gorilla/mux/otelmux"
 
 	"code.cloudfoundry.org/app-autoscaler/src/autoscaler/eventgenerator/config"
@@ -18,7 +19,6 @@ import (
 	"code.cloudfoundry.org/lager/v3"
 	"github.com/gorilla/mux"
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/tedsuo/ifrit"
 )
 
 type VarsFunc func(w http.ResponseWriter, r *http.Request, vars map[string]string)
@@ -69,14 +69,14 @@ func NewServer(logger lager.Logger, conf *config.Config, appMetricDB db.AppMetri
 	}
 }
 
-func (s *Server) CreateHealthServer() (ifrit.Runner, error) {
+func (s *Server) CreateHealthServer() (runner.Runner, error) {
 	if err := s.setupHealthRouter(); err != nil {
 		return nil, err
 	}
 	return helpers.NewHTTPServer(s.logger.Session("HealthServer"), s.conf.Health.ServerConfig, s.healthRouter)
 }
 
-func (s *Server) CreateCFServer(am auth.XFCCAuthMiddleware) (ifrit.Runner, error) {
+func (s *Server) CreateCFServer(am auth.XFCCAuthMiddleware) (runner.Runner, error) {
 	eventgenerator := s.createEventGeneratorRoutes()
 	eventgenerator.Use(am.XFCCAuthenticationMiddleware)
 
@@ -102,7 +102,7 @@ func (s *Server) setupHealthRouter() error {
 	return nil
 }
 
-func (s *Server) CreateMtlsServer() (ifrit.Runner, error) {
+func (s *Server) CreateMtlsServer() (runner.Runner, error) {
 	eventgenerator := s.createEventGeneratorRoutes()
 
 	return helpers.NewHTTPServer(s.logger, s.conf.Server, eventgenerator)