Add backend selection for agent (#463)

- add backend selection option
- by default it will auto-detect a backend

agent/runner.go

@@ -28,7 +28,7 @@ import (
 	"google.golang.org/grpc/metadata"
 
 	"github.com/woodpecker-ci/woodpecker/pipeline"
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/multipart"
 	"github.com/woodpecker-ci/woodpecker/pipeline/rpc"
 )

cli/exec/exec.go

@@ -15,8 +15,8 @@ import (
 
 	"github.com/woodpecker-ci/woodpecker/cli/common"
 	"github.com/woodpecker-ci/woodpecker/pipeline"
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
 	"github.com/woodpecker-ci/woodpecker/pipeline/backend/docker"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml/compiler"
@@ -158,8 +158,8 @@ func execWithAxis(c *cli.Context, axis matrix.Axis) error {
 		compiler.WithSecret(secrets...),
 		compiler.WithEnviron(droneEnv),
 	).Compile(conf)
-	engine, err := docker.NewEnv()
+	engine := docker.New()
-	if err != nil {
+	if err = engine.Load(); err != nil {
 		return err
 	}
 

cmd/agent/agent.go

@@ -31,7 +31,7 @@ import (
 	"google.golang.org/grpc/metadata"
 
 	"github.com/woodpecker-ci/woodpecker/agent"
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend/docker"
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
 	"github.com/woodpecker-ci/woodpecker/pipeline/rpc"
 )
 
@@ -138,13 +138,22 @@ func loop(c *cli.Context) error {
 					return
 				}
 
-				// new docker engine
+				// new engine
-				engine, err := docker.NewEnv()
+				engine, err := backend.FindEngine(c.String("backend-engine"))
 				if err != nil {
-					log.Error().Err(err).Msg("cannot create docker client")
+					log.Error().Err(err).Msgf("cannot find backend engine '%s'", c.String("backend-engine"))
 					return
 				}
 
+				// load enginge (e.g. init api client)
+				err = engine.Load()
+				if err != nil {
+					log.Error().Err(err).Msg("cannot load backend engine")
+					return
+				}
+
+				log.Debug().Msgf("loaded %s backend engine", engine.Name())
+
 				r := agent.NewRunner(client, filter, hostname, counter, &engine)
 				if err := r.Run(ctx); err != nil {
 					log.Error().Err(err).Msg("pipeline done with error")

cmd/agent/flags.go

@@ -110,4 +110,10 @@ var flags = []cli.Flag{
 		Usage:   "should the grpc server certificate be verified, only valid when WOODPECKER_GRPC_SECURE is true",
 		Value:   true,
 	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND"},
+		Name:    "backend-engine",
+		Usage:   "backend engine to run pipelines on",
+		Value:   "auto-detect",
+	},
 }

pipeline/backend/backend.go

@@ -1,29 +1,44 @@
 package backend
 
 import (
-	"context"
+	"fmt"
-	"io"
+
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend/docker"
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
-// Engine defines a container orchestration backend and is used
+var (
-// to create and manage container resources.
+	engines map[string]types.Engine
-type Engine interface {
+)
-	// Setup the pipeline environment.
-	Setup(context.Context, *Config) error
 
-	// Exec start the pipeline step.
+func init() {
-	Exec(context.Context, *Step) error
+	engines = make(map[string]types.Engine)
 
-	// Kill the pipeline step.
+	// TODO: disabled for now as kubernetes backend has not been implemented yet
-	Kill(context.Context, *Step) error
+	// kubernetes
+	// engine = kubernetes.New("", "", "")
+	// engines[engine.Name()] = engine
 
-	// Wait for the pipeline step to complete and returns
+	// docker
-	// the completion results.
+	engine := docker.New()
-	Wait(context.Context, *Step) (*State, error)
+	engines[engine.Name()] = engine
-
+}
-	// Tail the pipeline step logs.
+
-	Tail(context.Context, *Step) (io.ReadCloser, error)
+func FindEngine(engineName string) (types.Engine, error) {
-
+	if engineName == "auto-detect" {
-	// Destroy the pipeline environment.
+		for _, engine := range engines {
-	Destroy(context.Context, *Config) error
+			if engine.IsAvivable() {
+				return engine, nil
+			}
+		}
+
+		return nil, fmt.Errorf("Can't detect an avivable backend engine")
+	}
+
+	engine, ok := engines[engineName]
+	if !ok {
+		return nil, fmt.Errorf("Backend engine '%s' not found", engineName)
+	}
+
+	return engine, nil
 }

pipeline/backend/docker/convert.go

@@ -8,11 +8,11 @@ import (
 
 	"github.com/docker/docker/api/types/container"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 // returns a container configuration.
-func toConfig(proc *backend.Step) *container.Config {
+func toConfig(proc *types.Step) *container.Config {
 	config := &container.Config{
 		Image:        proc.Image,
 		Labels:       proc.Labels,
@@ -36,7 +36,7 @@ func toConfig(proc *backend.Step) *container.Config {
 }
 
 // returns a container host configuration.
-func toHostConfig(proc *backend.Step) *container.HostConfig {
+func toHostConfig(proc *types.Step) *container.HostConfig {
 	config := &container.HostConfig{
 		Resources: container.Resources{
 			CPUQuota:   proc.CPUQuota,
@@ -146,7 +146,7 @@ func toDev(paths []string) []container.DeviceMapping {
 
 // helper function that serializes the auth configuration as JSON
 // base64 payload.
-func encodeAuthToBase64(authConfig backend.Auth) (string, error) {
+func encodeAuthToBase64(authConfig types.Auth) (string, error) {
 	buf, err := json.Marshal(authConfig)
 	if err != nil {
 		return "", err

pipeline/backend/docker/docker.go

@@ -14,28 +14,38 @@ import (
 	"github.com/moby/term"
 	"github.com/rs/zerolog/log"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 type engine struct {
 	client client.APIClient
 }
 
-// New returns a new Docker Engine using the given client.
+// New returns a new Docker Engine.
-func New(cli client.APIClient) backend.Engine {
+func New() backend.Engine {
 	return &engine{
-		client: cli,
+		client: nil,
 	}
 }
 
-// NewEnv returns a new Docker Engine using the client connection
+func (e *engine) Name() string {
-// environment variables.
+	return "docker"
-func NewEnv() (backend.Engine, error) {
+}
+
+func (e *engine) IsAvivable() bool {
+	_, err := os.Stat("/.dockerenv")
+	return os.IsNotExist(err)
+}
+
+// Load new client for Docker Engine using environment variables.
+func (e *engine) Load() error {
 	cli, err := client.NewClientWithOpts(client.FromEnv)
 	if err != nil {
-		return nil, err
+		return err
 	}
-	return New(cli), nil
+	e.client = cli
+
+	return nil
 }
 
 func (e *engine) Setup(_ context.Context, conf *backend.Config) error {

pipeline/backend/kubernetes/kubernetes.go

@@ -3,8 +3,9 @@ package kubernetes
 import (
 	"context"
 	"io"
+	"os"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 type engine struct {
@@ -14,7 +15,7 @@ type engine struct {
 }
 
 // New returns a new Kubernetes Engine.
-func New(namespace, endpoint, token string) backend.Engine {
+func New(namespace, endpoint, token string) types.Engine {
 	return &engine{
 		namespace: namespace,
 		endpoint:  endpoint,
@@ -22,40 +23,53 @@ func New(namespace, endpoint, token string) backend.Engine {
 	}
 }
 
+func (e *engine) Name() string {
+	return "kubernetes"
+}
+
+func (e *engine) IsAvivable() bool {
+	host := os.Getenv("KUBERNETES_SERVICE_HOST")
+	return len(host) > 0
+}
+
+func (e *engine) Load() error {
+	return nil
+}
+
 // Setup the pipeline environment.
-func (e *engine) Setup(context.Context, *backend.Config) error {
+func (e *engine) Setup(context.Context, *types.Config) error {
 	// POST /api/v1/namespaces
 	return nil
 }
 
 // Start the pipeline step.
-func (e *engine) Exec(context.Context, *backend.Step) error {
+func (e *engine) 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, *backend.Step) error {
+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, *backend.Step) (*backend.State, error) {
+func (e *engine) 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, *backend.Step) (io.ReadCloser, error) {
+func (e *engine) 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, *backend.Config) error {
+func (e *engine) Destroy(context.Context, *types.Config) error {
 	// DELETE /api/v1/namespaces/{name}
 	return nil
 }

pipeline/backend/types.go

@@ -1,116 +0,0 @@
-package backend
-
-type (
-	// Config defines the runtime configuration of a pipeline.
-	Config struct {
-		Stages   []*Stage   `json:"pipeline"` // pipeline stages
-		Networks []*Network `json:"networks"` // network definitions
-		Volumes  []*Volume  `json:"volumes"`  // volume definitions
-		Secrets  []*Secret  `json:"secrets"`  // secret definitions
-	}
-
-	// Stage denotes a collection of one or more steps.
-	Stage struct {
-		Name  string  `json:"name,omitempty"`
-		Alias string  `json:"alias,omitempty"`
-		Steps []*Step `json:"steps,omitempty"`
-	}
-
-	// Step defines a container process.
-	Step struct {
-		Name         string            `json:"name"`
-		Alias        string            `json:"alias,omitempty"`
-		Image        string            `json:"image,omitempty"`
-		Pull         bool              `json:"pull,omitempty"`
-		Detached     bool              `json:"detach,omitempty"`
-		Privileged   bool              `json:"privileged,omitempty"`
-		WorkingDir   string            `json:"working_dir,omitempty"`
-		Environment  map[string]string `json:"environment,omitempty"`
-		Labels       map[string]string `json:"labels,omitempty"`
-		Entrypoint   []string          `json:"entrypoint,omitempty"`
-		Command      []string          `json:"command,omitempty"`
-		ExtraHosts   []string          `json:"extra_hosts,omitempty"`
-		Volumes      []string          `json:"volumes,omitempty"`
-		Tmpfs        []string          `json:"tmpfs,omitempty"`
-		Devices      []string          `json:"devices,omitempty"`
-		Networks     []Conn            `json:"networks,omitempty"`
-		DNS          []string          `json:"dns,omitempty"`
-		DNSSearch    []string          `json:"dns_search,omitempty"`
-		MemSwapLimit int64             `json:"memswap_limit,omitempty"`
-		MemLimit     int64             `json:"mem_limit,omitempty"`
-		ShmSize      int64             `json:"shm_size,omitempty"`
-		CPUQuota     int64             `json:"cpu_quota,omitempty"`
-		CPUShares    int64             `json:"cpu_shares,omitempty"`
-		CPUSet       string            `json:"cpu_set,omitempty"`
-		OnFailure    bool              `json:"on_failure,omitempty"`
-		OnSuccess    bool              `json:"on_success,omitempty"`
-		AuthConfig   Auth              `json:"auth_config,omitempty"`
-		NetworkMode  string            `json:"network_mode,omitempty"`
-		IpcMode      string            `json:"ipc_mode,omitempty"`
-		Sysctls      map[string]string `json:"sysctls,omitempty"`
-	}
-
-	// Auth defines registry authentication credentials.
-	Auth struct {
-		Username string `json:"username,omitempty"`
-		Password string `json:"password,omitempty"`
-		Email    string `json:"email,omitempty"`
-	}
-
-	// Conn defines a container network connection.
-	Conn struct {
-		Name    string   `json:"name"`
-		Aliases []string `json:"aliases"`
-	}
-
-	// Network defines a container network.
-	Network struct {
-		Name       string            `json:"name,omitempty"`
-		Driver     string            `json:"driver,omitempty"`
-		DriverOpts map[string]string `json:"driver_opts,omitempty"`
-	}
-
-	// Volume defines a container volume.
-	Volume struct {
-		Name       string            `json:"name,omitempty"`
-		Driver     string            `json:"driver,omitempty"`
-		DriverOpts map[string]string `json:"driver_opts,omitempty"`
-	}
-
-	// Secret defines a runtime secret
-	Secret struct {
-		Name  string `json:"name,omitempty"`
-		Value string `json:"value,omitempty"`
-		Mount string `json:"mount,omitempty"`
-		Mask  bool   `json:"mask,omitempty"`
-	}
-
-	// State defines a container state.
-	State struct {
-		// Container exit code
-		ExitCode int `json:"exit_code"`
-		// Container exited, true or false
-		Exited bool `json:"exited"`
-		// Container is oom killed, true or false
-		OOMKilled bool `json:"oom_killed"`
-	}
-
-	// // State defines the pipeline and process state.
-	// State struct {
-	// 	Pipeline struct {
-	// 		// Current pipeline step
-	// 		Step *Step `json:"step"`
-	// 		// Current pipeline error state
-	// 		Error error `json:"error"`
-	// 	}
-	//
-	// 	Process struct {
-	// 		// Container exit code
-	// 		ExitCode int `json:"exit_code"`
-	// 		// Container exited, true or false
-	// 		Exited bool `json:"exited"`
-	// 		// Container is oom killed, true or false
-	// 		OOMKilled bool `json:"oom_killed"`
-	// 	}
-	// }
-)

pipeline/backend/types/auth.go

@@ -0,0 +1,8 @@
+package types
+
+// Auth defines registry authentication credentials.
+type Auth struct {
+	Username string `json:"username,omitempty"`
+	Password string `json:"password,omitempty"`
+	Email    string `json:"email,omitempty"`
+}

pipeline/backend/types/config.go

@@ -0,0 +1,9 @@
+package types
+
+// Config defines the runtime configuration of a pipeline.
+type Config struct {
+	Stages   []*Stage   `json:"pipeline"` // pipeline stages
+	Networks []*Network `json:"networks"` // network definitions
+	Volumes  []*Volume  `json:"volumes"`  // volume definitions
+	Secrets  []*Secret  `json:"secrets"`  // secret definitions
+}

pipeline/backend/types/conn.go

@@ -0,0 +1,7 @@
+package types
+
+// Conn defines a container network connection.
+type Conn struct {
+	Name    string   `json:"name"`
+	Aliases []string `json:"aliases"`
+}

pipeline/backend/types/engine.go

@@ -0,0 +1,35 @@
+package types
+
+import (
+	"context"
+	"io"
+)
+
+// Engine defines a container orchestration backend and is used
+// to create and manage container resources.
+type Engine interface {
+	Name() string
+
+	IsAvivable() bool
+
+	Load() error
+
+	// Setup the pipeline environment.
+	Setup(context.Context, *Config) error
+
+	// 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)
+
+	// Tail the pipeline step logs.
+	Tail(context.Context, *Step) (io.ReadCloser, error)
+
+	// Destroy the pipeline environment.
+	Destroy(context.Context, *Config) error
+}

pipeline/backend/types/network.go

@@ -0,0 +1,8 @@
+package types
+
+// Network defines a container network.
+type Network struct {
+	Name       string            `json:"name,omitempty"`
+	Driver     string            `json:"driver,omitempty"`
+	DriverOpts map[string]string `json:"driver_opts,omitempty"`
+}

pipeline/backend/types/secret.go

@@ -0,0 +1,9 @@
+package types
+
+// Secret defines a runtime secret
+type Secret struct {
+	Name  string `json:"name,omitempty"`
+	Value string `json:"value,omitempty"`
+	Mount string `json:"mount,omitempty"`
+	Mask  bool   `json:"mask,omitempty"`
+}

pipeline/backend/types/stage.go

@@ -0,0 +1,8 @@
+package types
+
+// Stage denotes a collection of one or more steps.
+type Stage struct {
+	Name  string  `json:"name,omitempty"`
+	Alias string  `json:"alias,omitempty"`
+	Steps []*Step `json:"steps,omitempty"`
+}

pipeline/backend/types/state.go

@@ -0,0 +1,11 @@
+package types
+
+// State defines a container state.
+type State struct {
+	// Container exit code
+	ExitCode int `json:"exit_code"`
+	// Container exited, true or false
+	Exited bool `json:"exited"`
+	// Container is oom killed, true or false
+	OOMKilled bool `json:"oom_killed"`
+}

pipeline/backend/types/step.go

@@ -0,0 +1,35 @@
+package types
+
+// Step defines a container process.
+type Step struct {
+	Name         string            `json:"name"`
+	Alias        string            `json:"alias,omitempty"`
+	Image        string            `json:"image,omitempty"`
+	Pull         bool              `json:"pull,omitempty"`
+	Detached     bool              `json:"detach,omitempty"`
+	Privileged   bool              `json:"privileged,omitempty"`
+	WorkingDir   string            `json:"working_dir,omitempty"`
+	Environment  map[string]string `json:"environment,omitempty"`
+	Labels       map[string]string `json:"labels,omitempty"`
+	Entrypoint   []string          `json:"entrypoint,omitempty"`
+	Command      []string          `json:"command,omitempty"`
+	ExtraHosts   []string          `json:"extra_hosts,omitempty"`
+	Volumes      []string          `json:"volumes,omitempty"`
+	Tmpfs        []string          `json:"tmpfs,omitempty"`
+	Devices      []string          `json:"devices,omitempty"`
+	Networks     []Conn            `json:"networks,omitempty"`
+	DNS          []string          `json:"dns,omitempty"`
+	DNSSearch    []string          `json:"dns_search,omitempty"`
+	MemSwapLimit int64             `json:"memswap_limit,omitempty"`
+	MemLimit     int64             `json:"mem_limit,omitempty"`
+	ShmSize      int64             `json:"shm_size,omitempty"`
+	CPUQuota     int64             `json:"cpu_quota,omitempty"`
+	CPUShares    int64             `json:"cpu_shares,omitempty"`
+	CPUSet       string            `json:"cpu_set,omitempty"`
+	OnFailure    bool              `json:"on_failure,omitempty"`
+	OnSuccess    bool              `json:"on_success,omitempty"`
+	AuthConfig   Auth              `json:"auth_config,omitempty"`
+	NetworkMode  string            `json:"network_mode,omitempty"`
+	IpcMode      string            `json:"ipc_mode,omitempty"`
+	Sysctls      map[string]string `json:"sysctls,omitempty"`
+}

pipeline/backend/types/volume.go

@@ -0,0 +1,8 @@
+package types
+
+// Volume defines a container volume.
+type Volume struct {
+	Name       string            `json:"name,omitempty"`
+	Driver     string            `json:"driver,omitempty"`
+	DriverOpts map[string]string `json:"driver_opts,omitempty"`
+}

pipeline/frontend/yaml/compiler/compiler.go

@@ -3,7 +3,7 @@ package compiler
 import (
 	"fmt"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml"
 )

pipeline/frontend/yaml/compiler/convert.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/rs/zerolog/log"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml"
 )
 

pipeline/logger.go

@@ -1,7 +1,7 @@
 package pipeline
 
 import (
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/multipart"
 )
 

pipeline/option.go

@@ -3,7 +3,7 @@ package pipeline
 import (
 	"context"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 // Option configures a runtime option.

pipeline/parse.go

@@ -6,7 +6,7 @@ import (
 	"os"
 	"strings"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 // Parse parses the pipeline config from an io.Reader.

pipeline/pipeline.go

@@ -8,7 +8,7 @@ import (
 	"github.com/rs/zerolog/log"
 	"golang.org/x/sync/errgroup"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/multipart"
 )
 

pipeline/rpc/client_grpc.go

@@ -10,7 +10,7 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/rpc/proto"
 )
 

pipeline/rpc/peer.go

@@ -3,7 +3,7 @@ package rpc
 import (
 	"context"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 )
 
 type (

server/shared/procBuilder.go

@@ -24,7 +24,7 @@ import (
 
 	"github.com/drone/envsubst"
 
-	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
+	backend "github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml"
 	"github.com/woodpecker-ci/woodpecker/pipeline/frontend/yaml/compiler"