Fix docs and error message about pullSecretPath (#4381)

* Fix docs and error message about pullSecretPath

Author: chanseokoh

docs/content/en/docs/pipeline-stages/builders/docker.md

@@ -68,13 +68,13 @@ These credentials are configured in the `cluster` section with the following opt
 {{< schema root="ClusterDetails" >}}
 
 To set up the credentials for Kaniko refer to the [kaniko docs](https://github.com/GoogleContainerTools/kaniko#kubernetes-secret) (**Note**: Rename the downloaded JSON key to *kaniko-secret* without appending *.json*).
-Alternatively, the path to a credentials file can be set with the `pullSecret` option:
+Alternatively, the path to a credentials file can be set with the `pullSecretPath` option:
 ```yaml
 build:
   cluster:
     pullSecretName: pull-secret-in-kubernetes
     # OR
-    pullSecret: path-to-service-account-key-file
+    pullSecretPath: path-to-service-account-key-file
 ```
 Similarly, when pushing to a docker registry:
 ```yaml

pkg/skaffold/build/cluster/secret.go

@@ -56,7 +56,7 @@ func (b *Builder) setupPullSecret(out io.Writer) (func(), error) {
 	}
 	if b.PullSecretPath == "" {
 		// TODO: Remove the warning when pod health check can display pod failure errors.
-		logrus.Warnf("Setting secret keyfile path to %s. If this is incorrect, please specify using config key `pullSecret`.\nSee https://skaffold.dev/docs/references/yaml/#build-cluster-pullSecret", defaultKanikoSecretPath)
+		logrus.Warnf("Assuming the secret %s is mounted inside Kaniko pod with the filename %s. If your secret is mounted at different path, please specify using config key `pullSecretPath`.\nSee https://skaffold.dev/docs/references/yaml/#build-cluster-pullSecretPath", b.PullSecretName, defaultKanikoSecretPath)
 		b.PullSecretPath = defaultKanikoSecretPath
 		return func() {}, nil
 	}

pkg/skaffold/schema/defaults/defaults.go

@@ -265,7 +265,7 @@ func setDefaultClusterPullSecret(cluster *latest.ClusterDetails) error {
 	if cluster.PullSecretPath != "" {
 		absPath, err := homedir.Expand(cluster.PullSecretPath)
 		if err != nil {
-			return fmt.Errorf("unable to expand pullSecret %s", cluster.PullSecretPath)
+			return fmt.Errorf("unable to expand pullSecretPath %s", cluster.PullSecretPath)
 		}
 		cluster.PullSecretPath = absPath
 		random := ""