Add user as docker backend_option (#4526)

docs/docs/30-administration/22-backends/10-docker.md

@@ -18,6 +18,25 @@ FROM woodpeckerci/woodpecker-server:latest-alpine
 RUN apk add -U --no-cache docker-credential-ecr-login
 ```
 
+## Step specific configuration
+
+### Run user
+
+By default the docker backend starts the step container without the `--user` flag. This means the step container will use the default user of the container. To change this behavior you can set the `user` backend option to the preferred user/group:
+
+```yaml
+steps:
+  - name: example
+    image: alpine
+    commands:
+      - whoami
+    backend_options:
+      docker:
+        user: 65534:65534
+```
+
+The syntax is the same as the [docker run](https://docs.docker.com/engine/reference/run/#user) `--user` flag.
+
 ## Image cleanup
 
 The agent **will not** automatically remove images from the host. This task should be managed by the host system. For example, you can use a cron job to periodically do clean-up tasks for the CI runner.

docs/docs/30-administration/22-backends/40-kubernetes.md

@@ -12,7 +12,7 @@ In addition to [registries specified in the UI](../../20-usage/41-registries.md)
 
 Place these Secrets in namespace defined by `WOODPECKER_BACKEND_K8S_NAMESPACE` and provide the Secret names to Agents via `WOODPECKER_BACKEND_K8S_PULL_SECRET_NAMES`.
 
-## Job specific configuration
+## Step specific configuration
 
 ### Resources
 
@@ -67,7 +67,7 @@ To give steps access to the Kubernetes API via service account, take a look at [
 
 ### Node selector
 
-`nodeSelector` specifies the labels which are used to select the node on which the job will be executed.
+`nodeSelector` specifies the labels which are used to select the node on which the step will be executed.
 
 Labels defined here will be appended to a list which already contains `"kubernetes.io/arch"`.
 By default `"kubernetes.io/arch"` is inferred from the agents' platform. One can override it by setting that label in the `nodeSelector` section of the `backend_options`.

pipeline/backend/docker/backend_options.go

@@ -0,0 +1,21 @@
+package docker
+
+import (
+	"github.com/mitchellh/mapstructure"
+
+	backend "go.woodpecker-ci.org/woodpecker/v2/pipeline/backend/types"
+)
+
+// BackendOptions defines all the advanced options for the docker backend.
+type BackendOptions struct {
+	User string `mapstructure:"user"`
+}
+
+func parseBackendOptions(step *backend.Step) (BackendOptions, error) {
+	var result BackendOptions
+	if step == nil || step.BackendOptions == nil {
+		return result, nil
+	}
+	err := mapstructure.Decode(step.BackendOptions[EngineName], &result)
+	return result, err
+}

pipeline/backend/docker/backend_options_test.go

@@ -0,0 +1,56 @@
+package docker
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	backend "go.woodpecker-ci.org/woodpecker/v2/pipeline/backend/types"
+)
+
+func Test_parseBackendOptions(t *testing.T) {
+	tests := []struct {
+		name    string
+		step    *backend.Step
+		want    BackendOptions
+		wantErr bool
+	}{
+		{
+			name: "nil options",
+			step: &backend.Step{BackendOptions: nil},
+			want: BackendOptions{},
+		},
+		{
+			name: "empty options",
+			step: &backend.Step{BackendOptions: map[string]any{}},
+			want: BackendOptions{},
+		},
+		{
+			name: "with user option",
+			step: &backend.Step{BackendOptions: map[string]any{
+				"docker": map[string]any{
+					"user": "1000:1000",
+				},
+			}},
+			want: BackendOptions{User: "1000:1000"},
+		},
+		{
+			name:    "invalid backend options",
+			step:    &backend.Step{BackendOptions: map[string]any{"docker": "invalid"}},
+			want:    BackendOptions{},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseBackendOptions(tt.step)
+			if tt.wantErr {
+				assert.Error(t, err)
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}

pipeline/backend/docker/convert.go

@@ -31,7 +31,7 @@ import (
 const minVolumeComponents = 2
 
 // returns a container configuration.
-func (e *docker) toConfig(step *types.Step) *container.Config {
+func (e *docker) toConfig(step *types.Step, options BackendOptions) *container.Config {
 	e.windowsPathPatch(step)
 
 	config := &container.Config{
@@ -44,6 +44,7 @@ func (e *docker) toConfig(step *types.Step) *container.Config {
 		AttachStdout: true,
 		AttachStderr: true,
 		Volumes:      toVol(step.Volumes),
+		User:         options.User,
 	}
 	configEnv := make(map[string]string)
 	maps.Copy(configEnv, step.Environment)

pipeline/backend/docker/convert_test.go

@@ -131,15 +131,15 @@ func TestToContainerName(t *testing.T) {
 
 func TestStepToConfig(t *testing.T) {
 	// StepTypeCommands
-	conf := testEngine.toConfig(testCmdStep)
+	conf := testEngine.toConfig(testCmdStep, BackendOptions{})
 	if assert.NotNil(t, conf) {
 		assert.EqualValues(t, []string{"/bin/sh", "-c", "echo $CI_SCRIPT | base64 -d | /bin/sh -e"}, conf.Entrypoint)
 		assert.Nil(t, conf.Cmd)
 		assert.EqualValues(t, testCmdStep.UUID, conf.Labels["wp_uuid"])
 	}
 
 	// StepTypePlugin
-	conf = testEngine.toConfig(testPluginStep)
+	conf = testEngine.toConfig(testPluginStep, BackendOptions{})
 	if assert.NotNil(t, conf) {
 		assert.Nil(t, conf.Cmd)
 		assert.EqualValues(t, testPluginStep.UUID, conf.Labels["wp_uuid"])
@@ -174,7 +174,7 @@ func TestToConfigSmall(t *testing.T) {
 		Name:     "test",
 		UUID:     "09238932",
 		Commands: []string{"go test"},
-	})
+	}, BackendOptions{})
 
 	assert.NotNil(t, conf)
 	sort.Strings(conf.Env)
@@ -233,7 +233,7 @@ func TestToConfigFull(t *testing.T) {
 		AuthConfig:    backend.Auth{Username: "user", Password: "123456"},
 		NetworkMode:   "bridge",
 		Ports:         []backend.Port{{Number: 21}, {Number: 22}},
-	})
+	}, BackendOptions{})
 
 	assert.NotNil(t, conf)
 	sort.Strings(conf.Env)
@@ -286,7 +286,7 @@ func TestToWindowsConfig(t *testing.T) {
 		AuthConfig:  backend.Auth{Username: "user", Password: "123456"},
 		NetworkMode: "nat",
 		Ports:       []backend.Port{{Number: 21}, {Number: 22}},
-	})
+	}, BackendOptions{})
 
 	assert.NotNil(t, conf)
 	sort.Strings(conf.Env)

pipeline/backend/docker/docker.go

@@ -46,6 +46,7 @@ type docker struct {
 }
 
 const (
+	EngineName          = "docker"
 	networkDriverNAT    = "nat"
 	networkDriverBridge = "bridge"
 	volumeDriver        = "local"
@@ -59,7 +60,7 @@ func New() backend.Backend {
 }
 
 func (e *docker) Name() string {
-	return "docker"
+	return EngineName
 }
 
 func (e *docker) IsAvailable(ctx context.Context) bool {
@@ -170,9 +171,14 @@ func (e *docker) SetupWorkflow(ctx context.Context, conf *backend.Config, taskUU
 }
 
 func (e *docker) StartStep(ctx context.Context, step *backend.Step, taskUUID string) error {
+	options, err := parseBackendOptions(step)
+	if err != nil {
+		log.Error().Err(err).Msg("could not parse backend options")
+	}
+
 	log.Trace().Str("taskUUID", taskUUID).Msgf("start step %s", step.Name)
 
-	config := e.toConfig(step)
+	config := e.toConfig(step, options)
 	hostConfig := toHostConfig(step, &e.config)
 	containerName := toContainerName(step)
 
@@ -204,7 +210,7 @@ func (e *docker) StartStep(ctx context.Context, step *backend.Step, taskUUID str
 	// add default volumes to the host configuration
 	hostConfig.Binds = utils.DeduplicateStrings(append(hostConfig.Binds, e.config.volumes...))
 
-	_, err := e.client.ContainerCreate(ctx, config, hostConfig, nil, nil, containerName)
+	_, err = e.client.ContainerCreate(ctx, config, hostConfig, nil, nil, containerName)
 	if client.IsErrNotFound(err) {
 		// automatically pull and try to re-create the image if the
 		// failure is caused because the image does not exist.

pipeline/backend/kubernetes/backend_options.go

@@ -86,7 +86,7 @@ const (
 
 func parseBackendOptions(step *backend.Step) (BackendOptions, error) {
 	var result BackendOptions
-	if step.BackendOptions == nil {
+	if step == nil || step.BackendOptions == nil {
 		return result, nil
 	}
 	err := mapstructure.Decode(step.BackendOptions[EngineName], &result)