diff --git a/act/artifactcache/handler.go b/act/artifactcache/handler.go
index 71c00d52..62e8a097 100644
--- a/act/artifactcache/handler.go
+++ b/act/artifactcache/handler.go
@@ -234,7 +234,7 @@ func StartHandler(opts Options) (*Handler, error) {
 
 func (h *Handler) ExternalURL() string {
 	// TODO: make the external url configurable if necessary
-	return fmt.Sprintf("http://%s:%d", h.outboundIP, h.port)
+	return "http://" + net.JoinHostPort(h.outboundIP, strconv.Itoa(h.port))
 }
 
 func (h *Handler) baseURL(cred JobCredential) string {
diff --git a/act/artifactcache/handler_test.go b/act/artifactcache/handler_test.go
index 20ced3f6..e9364686 100644
--- a/act/artifactcache/handler_test.go
+++ b/act/artifactcache/handler_test.go
@@ -52,6 +52,10 @@ func signArtifactURL(h *Handler, id int64) string {
 	return h.signedArtifactURL(JobCredential{}, uint64(id), time.Now().Add(artifactURLTTL))
 }
 
+func TestHandler_ExternalURL(t *testing.T) {
+	assert.Equal(t, "http://[2001:db8::1]:8080", (&Handler{outboundIP: "2001:db8::1", port: 8080}).ExternalURL())
+}
+
 func TestHandler(t *testing.T) {
 	dir := filepath.Join(t.TempDir(), "artifactcache")
 	handler, err := StartHandler(Options{Dir: dir})
diff --git a/act/artifacts/server.go b/act/artifacts/server.go
index df2cf1de..1d85fb3f 100644
--- a/act/artifacts/server.go
+++ b/act/artifacts/server.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
+	"net"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -220,14 +221,14 @@ func Serve(ctx context.Context, artifactPath, addr, port string) context.CancelF
 	downloads(router, artifactPath)
 
 	server := &http.Server{
-		Addr:              fmt.Sprintf("%s:%s", addr, port),
+		Addr:              net.JoinHostPort(addr, port),
 		ReadHeaderTimeout: 2 * time.Second,
 		Handler:           router,
 	}
 
 	// run server
 	go func() {
-		logger.Infof("Start server on http://%s:%s", addr, port)
+		logger.Infof("Start server on http://%s", server.Addr)
 		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
 			logger.Fatal(err)
 		}
diff --git a/act/runner/run_context.go b/act/runner/run_context.go
index 0f51a942..f8c51451 100644
--- a/act/runner/run_context.go
+++ b/act/runner/run_context.go
@@ -16,6 +16,7 @@ import (
 	"fmt"
 	"io"
 	maps0 "maps"
+	"net"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -1646,7 +1647,7 @@ func imageOSFromImage(image string) string {
 func setActionRuntimeVars(rc *RunContext, env map[string]string) {
 	actionsRuntimeURL := os.Getenv("ACTIONS_RUNTIME_URL")
 	if actionsRuntimeURL == "" {
-		actionsRuntimeURL = fmt.Sprintf("http://%s:%s/", rc.Config.ArtifactServerAddr, rc.Config.ArtifactServerPort)
+		actionsRuntimeURL = "http://" + net.JoinHostPort(rc.Config.ArtifactServerAddr, rc.Config.ArtifactServerPort) + "/"
 	}
 	env["ACTIONS_RUNTIME_URL"] = actionsRuntimeURL
 
diff --git a/act/runner/run_context_test.go b/act/runner/run_context_test.go
index 89f30dcc..823543ac 100644
--- a/act/runner/run_context_test.go
+++ b/act/runner/run_context_test.go
@@ -1505,6 +1505,10 @@ func TestRunContextWithGithubEnvRunnerValues(t *testing.T) {
 	rc := createRunsOnRunContext(t, "ubuntu-latest")
 	rc.Config.RunnerName = "runner-1"
 	rc.Config.Secrets = map[string]string{"ACTIONS_STEP_DEBUG": "true"}
+	t.Setenv("ACTIONS_RUNTIME_URL", "")
+	rc.Config.ArtifactServerPath = "artifacts"
+	rc.Config.ArtifactServerAddr = "2001:db8::1"
+	rc.Config.ArtifactServerPort = "8080"
 
 	env := map[string]string{}
 	rc.withGithubEnv(ctx, &model.GithubContext{Workspace: "/workspace/owner/repo"}, env)
@@ -1513,4 +1517,5 @@ func TestRunContextWithGithubEnvRunnerValues(t *testing.T) {
 	assert.Equal(t, "self-hosted", env["RUNNER_ENVIRONMENT"])
 	assert.Equal(t, "/workspace/owner", env["RUNNER_WORKSPACE"])
 	assert.Equal(t, "1", env["RUNNER_DEBUG"])
+	assert.Equal(t, "http://[2001:db8::1]:8080/", env["ACTIONS_RUNTIME_URL"])
 }
diff --git a/e2e/gitea_fixture.go b/e2e/gitea_fixture.go
index a0f71c66..a5d9b93c 100644
--- a/e2e/gitea_fixture.go
+++ b/e2e/gitea_fixture.go
@@ -160,7 +160,7 @@ func StartGitea(ctx context.Context, cli mobyclient.APIClient) (*GiteaFixture, e
 		sharedNet, _ = selfNetwork(ctx, cli)
 	)
 	if sharedNet != "" {
-		baseURL = fmt.Sprintf("http://%s:3000", name)
+		baseURL = "http://" + net.JoinHostPort(name, "3000")
 		netConfig = &network.NetworkingConfig{
 			EndpointsConfig: map[string]*network.EndpointSettings{sharedNet: {}},
 		}
@@ -170,7 +170,7 @@ func StartGitea(ctx context.Context, cli mobyclient.APIClient) (*GiteaFixture, e
 		if err != nil {
 			return nil, fmt.Errorf("find a free host port: %w", err)
 		}
-		baseURL = fmt.Sprintf("http://%s:%d", host, port)
+		baseURL = "http://" + net.JoinHostPort(host.String(), strconv.Itoa(port))
 		hostConfig.PortBindings = network.PortMap{
 			containerPort: []network.PortBinding{{HostIP: host, HostPort: strconv.Itoa(port)}},
 		}
diff --git a/internal/app/cmd/cache-server.go b/internal/app/cmd/cache-server.go
index 72f86751..0ff68a34 100644
--- a/internal/app/cmd/cache-server.go
+++ b/internal/app/cmd/cache-server.go
@@ -6,8 +6,6 @@ package cmd
 import (
 	"errors"
 	"fmt"
-	"os"
-	"os/signal"
 
 	"gitea.com/gitea/runner/act/artifactcache"
 	"gitea.com/gitea/runner/internal/app/run"
@@ -67,10 +65,8 @@ func runCacheServer(configFile *string, cacheArgs *cacheServerArgs) func(cmd *co
 
 		log.Infof("cache server is listening on %v", cacheHandler.ExternalURL())
 
-		c := make(chan os.Signal, 1)
-		signal.Notify(c, os.Interrupt)
-		<-c
+		<-cmd.Context().Done()
 
-		return nil
+		return cacheHandler.Close()
 	}
 }
diff --git a/internal/app/cmd/cmd.go b/internal/app/cmd/cmd.go
index 4cb02420..e6fadd9b 100644
--- a/internal/app/cmd/cmd.go
+++ b/internal/app/cmd/cmd.go
@@ -82,7 +82,7 @@ func Execute(ctx context.Context) {
 	// hide completion command
 	rootCmd.CompletionOptions.HiddenDefaultCmd = true
 
-	if err := rootCmd.Execute(); err != nil {
+	if err := rootCmd.ExecuteContext(ctx); err != nil {
 		os.Exit(1)
 	}
 }
diff --git a/internal/app/run/runner.go b/internal/app/run/runner.go
index de71e153..2fc86715 100644
--- a/internal/app/run/runner.go
+++ b/internal/app/run/runner.go
@@ -281,10 +281,9 @@ func (r *Runner) SetCapabilitiesFromDeclare(resp *connect.Response[runnerv1.Decl
 }
 
 func (r *Runner) Run(ctx context.Context, task *runnerv1.Task) error {
-	if _, ok := r.runningTasks.Load(task.Id); ok {
+	if _, ok := r.runningTasks.LoadOrStore(task.Id, struct{}{}); ok {
 		return fmt.Errorf("task %d is already running", task.Id)
 	}
-	r.runningTasks.Store(task.Id, struct{}{})
 	defer r.runningTasks.Delete(task.Id)
 
 	r.runningCount.Add(1)