Fix pipeline backend autodetect (#545)

* refactor:
 - rename IsAvivable -> IsAvailable
 - drop depricated Kill
 - make sure backends implement interface
 - rename backend struct for ide (better info)

* docker backend fix autodetect

pipeline/backend/backend.go

@@ -27,7 +27,7 @@ func init() {
 func FindEngine(engineName string) (types.Engine, error) {
 	if engineName == "auto-detect" {
 		for _, engine := range engines {
-			if engine.IsAvivable() {
+			if engine.IsAvailable() {
 				return engine, nil
 			}
 		}

pipeline/backend/docker/docker.go

@@ -17,28 +17,31 @@ import (
 	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
-type engine struct {
+type docker struct {
 	client client.APIClient
 }
 
+// make sure docker implements Engine
+var _ backend.Engine = &docker{}
+
 // New returns a new Docker Engine.
 func New() backend.Engine {
-	return &engine{
+	return &docker{
 		client: nil,
 	}
 }
 
-func (e *engine) Name() string {
+func (e *docker) Name() string {
 	return "docker"
 }
 
-func (e *engine) IsAvivable() bool {
+func (e *docker) IsAvailable() bool {
-	_, err := os.Stat("/.dockerenv")
+	_, err := os.Stat("/var/run/docker.sock")
-	return os.IsNotExist(err)
+	return err == nil
 }
 
 // Load new client for Docker Engine using environment variables.
-func (e *engine) Load() error {
+func (e *docker) Load() error {
 	cli, err := client.NewClientWithOpts(client.FromEnv)
 	if err != nil {
 		return err
@@ -48,7 +51,7 @@ func (e *engine) Load() error {
 	return nil
 }
 
-func (e *engine) Setup(_ context.Context, conf *backend.Config) error {
+func (e *docker) Setup(_ context.Context, conf *backend.Config) error {
 	for _, vol := range conf.Volumes {
 		_, err := e.client.VolumeCreate(noContext, volume.VolumeCreateBody{
 			Name:       vol.Name,
@@ -73,7 +76,7 @@ func (e *engine) Setup(_ context.Context, conf *backend.Config) error {
 	return nil
 }
 
-func (e *engine) Exec(ctx context.Context, proc *backend.Step) error {
+func (e *docker) Exec(ctx context.Context, proc *backend.Step) error {
 	config := toConfig(proc)
 	hostConfig := toHostConfig(proc)
 
@@ -144,11 +147,7 @@ func (e *engine) Exec(ctx context.Context, proc *backend.Step) error {
 	return e.client.ContainerStart(ctx, proc.Name, startOpts)
 }
 
-func (e *engine) Kill(_ context.Context, proc *backend.Step) error {
+func (e *docker) Wait(ctx context.Context, proc *backend.Step) (*backend.State, error) {
-	return e.client.ContainerKill(noContext, proc.Name, "9")
-}
-
-func (e *engine) Wait(ctx context.Context, proc *backend.Step) (*backend.State, error) {
 	wait, errc := e.client.ContainerWait(ctx, proc.Name, "")
 	select {
 	case <-wait:
@@ -170,7 +169,7 @@ func (e *engine) Wait(ctx context.Context, proc *backend.Step) (*backend.State,
 	}, nil
 }
 
-func (e *engine) Tail(ctx context.Context, proc *backend.Step) (io.ReadCloser, error) {
+func (e *docker) Tail(ctx context.Context, proc *backend.Step) (io.ReadCloser, error) {
 	logs, err := e.client.ContainerLogs(ctx, proc.Name, logsOpts)
 	if err != nil {
 		return nil, err
@@ -187,7 +186,7 @@ func (e *engine) Tail(ctx context.Context, proc *backend.Step) (io.ReadCloser, e
 	return rc, nil
 }
 
-func (e *engine) Destroy(_ context.Context, conf *backend.Config) error {
+func (e *docker) Destroy(_ context.Context, conf *backend.Config) error {
 	for _, stage := range conf.Stages {
 		for _, step := range stage.Steps {
 			if err := e.client.ContainerKill(noContext, step.Name, "9"); err != nil {

pipeline/backend/docker/pool.go

@@ -20,15 +20,15 @@ package docker
 // func (p *Pool) Reserve(c context.Context) backend.Engine {
 // 	select {
 // 	case <-c.Done():
-// 	case engine := <-p.queue:
+// 	case docker := <-p.queue:
-// 		return engine
+// 		return docker
 // 	}
 // 	return nil
 // }
 //
 // // Release releases the Docker client back to the pool.
-// func (p *Pool) Release(engine backend.Engine) {
+// func (p *Pool) Release(docker backend.Engine) {
-// 	p.queue <- engine
+// 	p.queue <- docker
 // }
 
 // pool := docker.Pool(

pipeline/backend/kubernetes/kubernetes.go

@@ -8,68 +8,65 @@ import (
 	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
-type engine struct {
+type kube struct {
 	namespace string
 	endpoint  string
 	token     string
 }
 
+// make sure kube implements Engine
+var _ types.Engine = &kube{}
+
 // New returns a new Kubernetes Engine.
 func New(namespace, endpoint, token string) types.Engine {
-	return &engine{
+	return &kube{
 		namespace: namespace,
 		endpoint:  endpoint,
 		token:     token,
 	}
 }
 
-func (e *engine) Name() string {
+func (e *kube) Name() string {
 	return "kubernetes"
 }
 
-func (e *engine) IsAvivable() bool {
+func (e *kube) IsAvailable() bool {
 	host := os.Getenv("KUBERNETES_SERVICE_HOST")
 	return len(host) > 0
 }
 
-func (e *engine) Load() error {
+func (e *kube) Load() error {
 	return nil
 }
 
 // Setup the pipeline environment.
-func (e *engine) Setup(context.Context, *types.Config) error {
+func (e *kube) Setup(context.Context, *types.Config) error {
 	// POST /api/v1/namespaces
 	return nil
 }
 
-// Start the pipeline step.
+// Exec the pipeline step.
-func (e *engine) Exec(context.Context, *types.Step) error {
+func (e *kube) Exec(context.Context, *types.Step) error {
 	// POST /api/v1/namespaces/{namespace}/pods
 	return nil
 }
 
-// DEPRECATED
-// Kill the pipeline step.
-func (e *engine) Kill(context.Context, *types.Step) error {
-	return nil
-}
-
 // Wait for the pipeline step to complete and returns
 // the completion results.
-func (e *engine) Wait(context.Context, *types.Step) (*types.State, error) {
+func (e *kube) Wait(context.Context, *types.Step) (*types.State, error) {
 	// GET /api/v1/watch/namespaces/{namespace}/pods
 	// GET /api/v1/watch/namespaces/{namespace}/pods/{name}
 	return nil, nil
 }
 
 // Tail the pipeline step logs.
-func (e *engine) Tail(context.Context, *types.Step) (io.ReadCloser, error) {
+func (e *kube) Tail(context.Context, *types.Step) (io.ReadCloser, error) {
 	// GET /api/v1/namespaces/{namespace}/pods/{name}/log
 	return nil, nil
 }
 
 // Destroy the pipeline environment.
-func (e *engine) Destroy(context.Context, *types.Config) error {
+func (e *kube) Destroy(context.Context, *types.Config) error {
 	// DELETE /api/v1/namespaces/{name}
 	return nil
 }

pipeline/backend/types/engine.go

@@ -10,7 +10,7 @@ import (
 type Engine interface {
 	Name() string
 
-	IsAvivable() bool
+	IsAvailable() bool
 
 	Load() error
 
@@ -20,9 +20,6 @@ type Engine interface {
 	// Exec start the pipeline step.
 	Exec(context.Context, *Step) error
 
-	// Kill the pipeline step.
-	Kill(context.Context, *Step) error
-
 	// Wait for the pipeline step to complete and returns
 	// the completion results.
 	Wait(context.Context, *Step) (*State, error)