Fix backend detection (#3353)

closes #3352

cli/exec/exec.go

@@ -213,13 +213,12 @@ func execWithAxis(c *cli.Context, file, repoPath string, axis matrix.Axis) error
 	}
 
 	backendCtx := context.WithValue(c.Context, backendTypes.CliContext, c)
-	backend.Init([]backendTypes.Backend{
+	backends := []backendTypes.Backend{
+		kubernetes.New(),
 		docker.New(),
 		local.New(),
-		kubernetes.New(),
+	}
-	})
+	backendEngine, err := backend.FindBackend(backendCtx, backends, c.String("backend-engine"))
-
-	backendEngine, err := backend.FindBackend(backendCtx, c.String("backend-engine"))
 	if err != nil {
 		return err
 	}

cmd/agent/core/agent.go

@@ -47,7 +47,7 @@ import (
 	"go.woodpecker-ci.org/woodpecker/v2/version"
 )
 
-func run(c *cli.Context, backendEngines []types.Backend) error {
+func run(c *cli.Context, backends []types.Backend) error {
 	agentConfigPath := c.String("agent-config")
 	hostname := c.String("hostname")
 	if len(hostname) == 0 {
@@ -153,9 +153,8 @@ func run(c *cli.Context, backendEngines []types.Backend) error {
 
 	// new engine
 	backendCtx := context.WithValue(ctx, types.CliContext, c)
-	backend.Init(backendEngines)
 	backendName := c.String("backend-engine")
-	backendEngine, err := backend.FindBackend(backendCtx, backendName)
+	backendEngine, err := backend.FindBackend(backendCtx, backends, backendName)
 	if err != nil {
 		log.Error().Err(err).Msgf("cannot find backend engine '%s'", backendName)
 		return err

cmd/agent/main.go

@@ -24,8 +24,8 @@ import (
 
 func main() {
 	core.RunAgent([]backendTypes.Backend{
+		kubernetes.New(),
 		docker.New(),
 		local.New(),
-		kubernetes.New(),
 	})
 }

pipeline/backend/backend.go

@@ -21,19 +21,7 @@ import (
 	"go.woodpecker-ci.org/woodpecker/v2/pipeline/backend/types"
 )
 
-var (
+func FindBackend(ctx context.Context, backends []types.Backend, backendName string) (types.Backend, error) {
-	backendsByName map[string]types.Backend
-	backends       []types.Backend
-)
-
-func Init(backends []types.Backend) {
-	backendsByName = make(map[string]types.Backend)
-	for _, engine := range backends {
-		backendsByName[engine.Name()] = engine
-	}
-}
-
-func FindBackend(ctx context.Context, backendName string) (types.Backend, error) {
 	if backendName == "auto-detect" {
 		for _, engine := range backends {
 			if engine.IsAvailable(ctx) {
@@ -44,10 +32,11 @@ func FindBackend(ctx context.Context, backendName string) (types.Backend, error)
 		return nil, fmt.Errorf("can't detect an available backend engine")
 	}
 
-	engine, ok := backendsByName[backendName]
+	for _, engine := range backends {
-	if !ok {
+		if engine.Name() == backendName {
-		return nil, fmt.Errorf("backend engine '%s' not found", backendName)
+			return engine, nil
+		}
 	}
 
-	return engine, nil
+	return nil, fmt.Errorf("backend engine '%s' not found", backendName)
 }