fix: reduce idle runner polling by default

Raise the default idle fetch backoff ceiling to reduce steady-state FetchTask traffic from idle runner fleets while keeping the value configurable for installations that need faster idle polling.

Fixes: https://gitea.com/gitea/runner/issues/762

Co-Authored-By: GPT-5 Codex <codex@openai.com>

act/runner/run_context.go

@@ -379,13 +379,6 @@ func (rc *RunContext) startJobContainer() common.Executor {
 
 		// add service containers
 		for serviceID, spec := range rc.Run.Job().Services {
-			// GitHub compatibility: skip services whose image evaluates to an
-			// empty string, enabling conditional services via expressions
-			serviceImage := rc.ExprEval.Interpolate(ctx, spec.Image)
-			if serviceImage == "" {
-				logger.Infof("The service '%s' will not be started because the container definition has an empty image.", serviceID)
-				continue
-			}
 			// interpolate env
 			interpolatedEnvs := make(map[string]string, len(spec.Env))
 			for k, v := range spec.Env {
@@ -424,7 +417,7 @@ func (rc *RunContext) startJobContainer() common.Executor {
 			c := container.NewContainer(&container.NewContainerInput{
 				Name:           serviceContainerName,
 				WorkingDir:     ext.ToContainerPath(rc.Config.Workdir),
-				Image:          serviceImage,
+				Image:          rc.ExprEval.Interpolate(ctx, spec.Image),
 				Username:       username,
 				Password:       password,
 				Cmd:            interpolatedCmd,

act/runner/runner_test.go

@@ -303,7 +303,6 @@ func TestRunEvent(t *testing.T) {
 		// services
 		{workdir, "services", "push", "", platforms, secrets},
 		{workdir, "services-with-container", "push", "", platforms, secrets},
-		{workdir, "services-empty-image", "push", "", platforms, secrets},
 
 		// local remote action overrides
 		{workdir, "local-remote-action-overrides", "push", "", platforms, secrets},

act/runner/testdata/services-empty-image/push.yml

@@ -1,10 +0,0 @@
-name: services-empty-image
-on: push
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    services:
-      db:
-        image: ${{ false && 'postgres:16' || '' }}
-    steps:
-      - run: echo "empty-image service was skipped"

go.mod

@@ -29,7 +29,6 @@ require (
 	github.com/opencontainers/selinux v1.15.1
 	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.23.2
-	github.com/prometheus/client_model v0.6.2
 	github.com/rhysd/actionlint v1.7.12
 	github.com/sirupsen/logrus v1.9.4
 	github.com/spf13/cobra v1.10.2
@@ -38,7 +37,7 @@ require (
 	github.com/timshannon/bolthold v0.0.0-20240314194003-30aac6950928
 	go.etcd.io/bbolt v1.5.0
 	go.yaml.in/yaml/v4 v4.0.0-rc.3
-	golang.org/x/sys v0.47.0
+	golang.org/x/sys v0.46.0
 	golang.org/x/term v0.44.0
 	google.golang.org/protobuf v1.36.11
 	gotest.tools/v3 v3.5.2
@@ -85,6 +84,7 @@ require (
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/pjbgf/sha1cd v0.6.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.66.1 // indirect
 	github.com/prometheus/procfs v0.17.0 // indirect
 	github.com/robfig/cron/v3 v3.0.1 // indirect

go.sum

@@ -262,8 +262,6 @@ golang.org/x/sys v0.4.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
 golang.org/x/sys v0.46.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
-golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
-golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.44.0 h1:0rLvDRCtNj0gZkyIXhCyOb2OAzEhLVqc4B+hrsBhrmc=
 golang.org/x/term v0.44.0/go.mod h1:7ze4MdzUzLXpSAoFP1H0bOI9aXDqveSvatT5vKcFh2Y=

internal/pkg/config/config.example.yaml

@@ -39,7 +39,7 @@ runner:
   # The maximum interval for fetching the job from the Gitea instance.
   # The runner uses exponential backoff when idle, increasing the interval up to this maximum.
   # Set to 0 or same as fetch_interval to disable backoff.
-  fetch_interval_max: 5s
+  fetch_interval_max: 1m
   # While idle, remove stale bind-workdir task directories and orphaned host-mode
   # scratch directories (left behind when a host cleanup delete stalls) older than
   # this duration. Setting either workdir_cleanup_age or idle_cleanup_interval to 0
@@ -110,11 +110,6 @@ cache:
   dir: ""
   # Outbound IP or hostname that job containers use to reach this runner's cache server.
   # Leave empty to detect automatically. 0.0.0.0 is not valid here.
-  # If the runner itself runs in Docker, automatic detection can choose an
-  # address on the runner container's network that job containers cannot reach
-  # when the runner creates a separate per-job network. In that case, set this
-  # to a hostname/IP reachable from job containers, and set port to a fixed
-  # published port or put the job containers on a shared Docker network.
   # Ignored when external_server is set.
   host: ""
   # Port for the built-in cache server. 0 picks a random free port.
@@ -138,8 +133,6 @@ container:
   # Specifies the network to which the container will connect.
   # Could be host, bridge or the name of a custom network.
   # If it's empty, runner will create a network automatically.
-  # For dockerized runners using the built-in cache server, a custom shared
-  # network can be required so job containers can reach cache.host/cache.port.
   # Deprecated: `network_mode` is still accepted for old configs; use `network` instead.
   network: ""
   # network_create_options only apply when `network` is left empty and the runner

internal/pkg/config/config.go

@@ -183,7 +183,7 @@ func LoadDefault(file string) (*Config, error) {
 		cfg.Runner.FetchInterval = 2 * time.Second
 	}
 	if cfg.Runner.FetchIntervalMax <= 0 {
-		cfg.Runner.FetchIntervalMax = 5 * time.Second
+		cfg.Runner.FetchIntervalMax = time.Minute
 	}
 	if cfg.Runner.WorkdirCleanupAge == 0 && !definedRunnerKeys["workdir_cleanup_age"] {
 		cfg.Runner.WorkdirCleanupAge = 24 * time.Hour

internal/pkg/config/config_test.go

@@ -48,6 +48,12 @@ func TestLoadDefault_DefaultsWorkdirCleanupAge(t *testing.T) {
 	assert.Equal(t, 10*time.Minute, cfg.Runner.IdleCleanupInterval)
 }
 
+func TestLoadDefault_DefaultsIdleFetchBackoffMax(t *testing.T) {
+	cfg, err := LoadDefault("")
+	require.NoError(t, err)
+	assert.Equal(t, time.Minute, cfg.Runner.FetchIntervalMax)
+}
+
 func TestLoadDefault_UsesConfiguredWorkdirCleanupAge(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "config.yaml")