set ContainerDaemonSocket as docker_host

internal/app/cmd/daemon.go

@@ -63,9 +63,18 @@ func runDaemon(ctx context.Context, configFile *string) func(cmd *cobra.Command,
 		}
 
 		if ls.RequireDocker() {
-			if err := envcheck.CheckIfDockerRunning(ctx, cfg); err != nil {
+			dockerSocketPath, err := getDockerSocketPath(cfg.Container.DockerHost)
+			if err != nil {
 				return err
 			}
+			if err := envcheck.CheckIfDockerRunning(ctx, dockerSocketPath); err != nil {
+				return err
+			}
+			if cfg.Container.DockerHost == "" {
+				cfg.Container.DockerHost = dockerSocketPath
+			}
+
+			os.Setenv("DOCKER_HOST", dockerSocketPath)
 		}
 
 		cli := client.New(

internal/app/cmd/docker_deamon.go

@@ -0,0 +1,56 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func getDockerSocketPath(configDockerHost string) (string, error) {
+	var socketPath string
+
+	// a `-` means don't mount the docker socket to job containers
+	if configDockerHost != "" && configDockerHost != "-" {
+		socketPath = configDockerHost
+	} else {
+		socket, found := socketLocation()
+		if !found {
+			return "", fmt.Errorf("daemon Docker Engine socket not found and docker_host config was invalid")
+		} else {
+			socketPath = socket
+		}
+	}
+
+	return socketPath, nil
+}
+
+var commonSocketPaths = []string{
+	"/var/run/docker.sock",
+	"/var/run/podman/podman.sock",
+	"$HOME/.colima/docker.sock",
+	"$XDG_RUNTIME_DIR/docker.sock",
+	`\\.\pipe\docker_engine`,
+	"$HOME/.docker/run/docker.sock",
+}
+
+// returns socket path or false if not found any
+func socketLocation() (string, bool) {
+	if dockerHost, exists := os.LookupEnv("DOCKER_HOST"); exists {
+		return dockerHost, true
+	}
+
+	for _, p := range commonSocketPaths {
+		if _, err := os.Lstat(os.ExpandEnv(p)); err == nil {
+			if strings.HasPrefix(p, `\\.\`) {
+				return "npipe://" + filepath.ToSlash(os.ExpandEnv(p)), true
+			}
+			return "unix://" + filepath.ToSlash(os.ExpandEnv(p)), true
+		}
+	}
+
+	return "", false
+}

internal/app/run/runner.go

@@ -179,27 +179,28 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 		BindWorkdir:    false,
 		ActionCacheDir: filepath.FromSlash(r.cfg.Host.WorkdirParent),
 
-		ReuseContainers:      false,
-		ForcePull:            false,
-		ForceRebuild:         false,
-		LogOutput:            true,
-		JSONLogger:           false,
-		Env:                  r.envs,
-		Secrets:              task.Secrets,
-		GitHubInstance:       strings.TrimSuffix(r.client.Address(), "/"),
-		AutoRemove:           true,
-		NoSkipCheckout:       true,
-		PresetGitHubContext:  preset,
-		EventJSON:            string(eventJSON),
-		ContainerNamePrefix:  fmt.Sprintf("GITEA-ACTIONS-TASK-%d", task.Id),
-		ContainerMaxLifetime: maxLifetime,
-		ContainerNetworkMode: container.NetworkMode(r.cfg.Container.Network),
-		ContainerOptions:     r.cfg.Container.Options,
-		Privileged:           r.cfg.Container.Privileged,
-		DefaultActionsURLs:   parseDefaultActionsURLs(taskContext["gitea_default_actions_url"].GetStringValue()),
-		PlatformPicker:       r.labels.PickPlatform,
-		Vars:                 task.Vars,
-		ValidVolumes:         r.cfg.Container.ValidVolumes,
+		ReuseContainers:       false,
+		ForcePull:             false,
+		ForceRebuild:          false,
+		LogOutput:             true,
+		JSONLogger:            false,
+		Env:                   r.envs,
+		Secrets:               task.Secrets,
+		GitHubInstance:        strings.TrimSuffix(r.client.Address(), "/"),
+		AutoRemove:            true,
+		NoSkipCheckout:        true,
+		PresetGitHubContext:   preset,
+		EventJSON:             string(eventJSON),
+		ContainerNamePrefix:   fmt.Sprintf("GITEA-ACTIONS-TASK-%d", task.Id),
+		ContainerMaxLifetime:  maxLifetime,
+		ContainerNetworkMode:  container.NetworkMode(r.cfg.Container.Network),
+		ContainerOptions:      r.cfg.Container.Options,
+		ContainerDaemonSocket: r.cfg.Container.DockerHost,
+		Privileged:            r.cfg.Container.Privileged,
+		DefaultActionsURLs:    parseDefaultActionsURLs(taskContext["gitea_default_actions_url"].GetStringValue()),
+		PlatformPicker:        r.labels.PickPlatform,
+		Vars:                  task.Vars,
+		ValidVolumes:          r.cfg.Container.ValidVolumes,
 	}
 
 	rr, err := runner.New(runnerConfig)

internal/pkg/config/config.example.yaml

@@ -69,8 +69,9 @@ container:
   #   - '**'
   valid_volumes: []
   # overrides the docker client host with the specified one.
-  # default value is the value of DOCKER_HOST environment variable.
-  # if DOCKER_HOST is not set, the default value is unix:///var/run/docker.sock
+  # If it's empty, act_runner will find an available docker host automatically.
+  # If it's "-", act_runner will find an available docker host automatically, but the docker host won't be mounted to the job containers and service containers.
+  # If it's not empty or "-", the specified docker host will be used. An error will be returned if it doesn't work.
   docker_host: ""
 
 host:

internal/pkg/envcheck/docker.go

@@ -8,17 +8,15 @@ import (
 	"fmt"
 
 	"github.com/docker/docker/client"
-
-	"gitea.com/gitea/act_runner/internal/pkg/config"
 )
 
-func CheckIfDockerRunning(ctx context.Context, cfg *config.Config) error {
+func CheckIfDockerRunning(ctx context.Context, configDockerHost string) error {
 	opts := []client.Opt{
 		client.FromEnv,
 	}
 
-	if cfg.Container.DockerHost != "" {
-		opts = append(opts, client.WithHost(cfg.Container.DockerHost))
+	if configDockerHost != "" {
+		opts = append(opts, client.WithHost(configDockerHost))
 	}
 
 	cli, err := client.NewClientWithOpts(opts...)