Removed Kubernetes default image pull secret name (woodpecker-ci#4005)

Co-authored-by: qwerty287 <[email protected]>

docs/docs/91-migrations.md

@@ -16,6 +16,7 @@ Some versions need some changes to the server configuration or the pipeline conf
 - Deprecated `steps.[name].group` in favor of `steps.[name].depends_on` (see [workflow syntax](./20-usage/20-workflow-syntax.md#depends_on) to learn how to set dependencies)
 - Removed `WOODPECKER_ROOT_PATH` and `WOODPECKER_ROOT_URL` config variables. Use `WOODPECKER_HOST` with a path instead
 - Pipelines without a config file will now be skipped instead of failing
+- Removed implicitly defined `regcred` image pull secret name. Set it explicitly via `WOODPECKER_BACKEND_K8S_PULL_SECRET_NAMES`
 - Deprecated `includes` and `excludes` support from **event** filter
 - Deprecated uppercasing all secret env vars, instead, the value of the `secrets` property is used. [Read more](./20-usage/40-secrets.md#use-secrets-in-commands)
 - Deprecated alternative names for secrets, use `environment` with `from_secret`

pipeline/backend/kubernetes/flags.go

@@ -82,7 +82,6 @@ var Flags = []cli.Flag{
 		Sources: cli.EnvVars("WOODPECKER_BACKEND_K8S_PULL_SECRET_NAMES"),
 		Name:    "backend-k8s-pod-image-pull-secret-names",
 		Usage:   "backend k8s pull secret names for private registries",
-		Value:   []string{"regcred"},
 	},
 	&cli.BoolFlag{
 		Sources: cli.EnvVars("WOODPECKER_BACKEND_K8S_ALLOW_NATIVE_SECRETS"),

pipeline/backend/kubernetes/kubernetes.go

@@ -100,10 +100,6 @@ func configFromCliContext(ctx context.Context) (*config, error) {
 				},
 				NativeSecretsAllowFromStep: c.Bool("backend-k8s-allow-native-secrets"),
 			}
-			// TODO: remove in next major
-			if len(config.ImagePullSecretNames) == 1 && config.ImagePullSecretNames[0] == "regcred" {
-				log.Warn().Msg("WOODPECKER_BACKEND_K8S_PULL_SECRET_NAMES is set to the default ('regcred'). It will default to empty in Woodpecker 3.0. Set it explicitly before then.")
-			}
 			// Unmarshal label and annotation settings here to ensure they're valid on startup
 			if labels := c.String("backend-k8s-pod-labels"); labels != "" {
 				if err := yaml.Unmarshal([]byte(labels), &config.PodLabels); err != nil {