add custom secret field support

plugin/kubernetes/README.md

@@ -146,6 +146,8 @@ apiVersion: sshpiper.com/v1beta1
 kind: Pipe
 metadata:
   name: pipe-publickey
+  annotations:
+    privatekey_field_name: privatekey # this is optional, default is privatekey  
 spec:
   from:
   - username: ".*" # catch all    

plugin/kubernetes/kubernetes.go

@@ -165,7 +165,13 @@ func (p *plugin) createUpstream(conn libplugin.ConnMetadata, pipe *piperv1beta1.
 		return nil, err
 	}
 
-	data := secret.Data["privatekey"]
+	anno := pipe.GetAnnotations()
+	k := anno["privatekey_field_name"]
+	if k == "" {
+		k = "privatekey"
+	}
+
+	data := secret.Data[k]
 	if data != nil {
 		u.Auth = libplugin.CreatePrivateKeyAuth(data)
 		p.cache.Set(conn.UniqueID(), pipe, gocache.DefaultExpiration)

plugin/kubernetes/sample.yaml

@@ -153,6 +153,8 @@ apiVersion: sshpiper.com/v1beta1
 kind: Pipe
 metadata:
   name: pipe-publickey
+  annotations:
+    privatekey_field_name: privatekey # this is optional, default is privatekey
 spec:
   from:
   - username: ".*" # catch all