Improve the usage of `docker_host` configuration (#260)

Follow #242, #244
Fixes #258

Users could use `docker_host` configuration to specify which docker daemon will be used by act_runner.
- If `docker_host` is **empty**, act_runner will find an available docker host automatically.
- If `docker_host` is **"-"**, 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 `docker_host` is **not empty or "-"**, the specified docker host will be used. An error will be returned if it doesn't work.

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/260
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>

internal/app/cmd/daemon.go

@@ -63,9 +63,28 @@ 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 dockerSocketPath passes the check, override DOCKER_HOST with dockerSocketPath
+			os.Setenv("DOCKER_HOST", dockerSocketPath)
+			// empty cfg.Container.DockerHost means act_runner need to find an available docker host automatically
+			// and assign the path to cfg.Container.DockerHost
+			if cfg.Container.DockerHost == "" {
+				cfg.Container.DockerHost = dockerSocketPath
+			}
+			// check the scheme, if the scheme is not npipe or unix
+			// set cfg.Container.DockerHost to "-" because it can't be mounted to the job conatiner
+			if protoIndex := strings.Index(cfg.Container.DockerHost, "://"); protoIndex != -1 {
+				scheme := cfg.Container.DockerHost[:protoIndex]
+				if !strings.EqualFold(scheme, "npipe") && !strings.EqualFold(scheme, "unix") {
+					cfg.Container.DockerHost = "-"
+				}
+			}
 		}
 
 		cli := client.New(
@@ -140,3 +159,17 @@ func initLogging(cfg *config.Config) {
 		}
 	}
 }
+
+func getDockerSocketPath(configDockerHost string) (string, error) {
+	// a `-` means don't mount the docker socket to job containers
+	if configDockerHost != "" && configDockerHost != "-" {
+		return configDockerHost, nil
+	}
+
+	socket, found := os.LookupEnv("DOCKER_HOST")
+	if found {
+		return socket, nil
+	}
+
+	return "", fmt.Errorf("daemon Docker Engine socket not found and docker_host config was invalid")
+}

internal/app/run/runner.go

@@ -195,6 +195,7 @@ func (r *Runner) run(ctx context.Context, task *runnerv1.Task, reporter *report.
 		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,

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 it's empty, act_runner will find an available docker host automatically.
-  # if DOCKER_HOST is not set, the default value is unix:///var/run/docker.sock
+  # 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 != "" {
+	if configDockerHost != "" {
-		opts = append(opts, client.WithHost(cfg.Container.DockerHost))
+		opts = append(opts, client.WithHost(configDockerHost))
 	}
 
 	cli, err := client.NewClientWithOpts(opts...)