Various enhancements in configuration (#1645)

- backends: move to cli flags instead of os.Getenv
- ssh: support 2fa with key and password
- allow to set grpc jwt secret (solves todo)
- allow to set default and max timeout (solves todo)

Closes https://github.com/woodpecker-ci/woodpecker/issues/896
Closes https://github.com/woodpecker-ci/woodpecker/issues/1131

cmd/agent/agent.go

@@ -154,14 +154,15 @@ func loop(c *cli.Context) error {
 		sigterm.Set()
 	})
 
-	backend.Init(context.WithValue(ctx, types.CliContext, c))
+	backendCtx := context.WithValue(ctx, types.CliContext, c)
+	backend.Init(backendCtx)
 
 	var wg sync.WaitGroup
 	parallel := c.Int("max-workflows")
 	wg.Add(parallel)
 
 	// new engine
-	engine, err := backend.FindEngine(c.String("backend-engine"))
+	engine, err := backend.FindEngine(backendCtx, c.String("backend-engine"))
 	if err != nil {
 		log.Error().Err(err).Msgf("cannot find backend engine '%s'", c.String("backend-engine"))
 		return err
@@ -195,7 +196,7 @@ func loop(c *cli.Context) error {
 			defer wg.Done()
 
 			// load engine (e.g. init api client)
-			err = engine.Load()
+			err = engine.Load(backendCtx)
 			if err != nil {
 				log.Error().Err(err).Msg("cannot load backend engine")
 				return

cmd/agent/flags.go

@@ -108,7 +108,50 @@ var flags = []cli.Flag{
 		Value:   "auto-detect",
 	},
 
-	// TODO: add flags of backends
+	// backend docker
+	&cli.BoolFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_DOCKER_ENABLE_IPV6"},
+		Name:    "backend-docker-ipv6",
+		Usage:   "backend docker enable IPV6",
+		Value:   false,
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_DOCKER_NETWORK"},
+		Name:    "backend-docker-network",
+		Usage:   "backend docker network",
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_DOCKER_VOLUMES"},
+		Name:    "backend-docker-volumes",
+		Usage:   "backend docker volumes (comma separated)",
+	},
+
+	// backend ssh
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_SSH_ADDRESS"},
+		Name:    "backend-ssh-address",
+		Usage:   "backend ssh address",
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_SSH_USER"},
+		Name:    "backend-ssh-user",
+		Usage:   "backend ssh user",
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_SSH_KEY"},
+		Name:    "backend-ssh-key",
+		Usage:   "backend ssh key file",
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_SSH_KEY_PASSWORD"},
+		Name:    "backend-ssh-key-password",
+		Usage:   "backend ssh key password",
+	},
+	&cli.StringFlag{
+		EnvVars: []string{"WOODPECKER_BACKEND_SSH_PASSWORD"},
+		Name:    "backend-ssh-password",
+		Usage:   "backend ssh password",
+	},
 
 	// backend k8s
 	&cli.StringFlag{