Use port forwarding

Contents

Overview

Beginning with WebLogic Kubernetes Operator version 3.3.2, or earlier if you are using an Istio-enabled domain, you can use the kubectl port-forward command to set up external access for the WebLogic Server Administration Console, the Remote Console, and WLST. This approach is particularly useful for managing WebLogic from a private local network without exposing WebLogic’s ports to a public network.

Here are the steps:

  1. Set up WebLogic Administration Server network channels for port forward access.
  2. If you are setting up WLST access and your port forwarding local port is not going to be the same as the port number on the WebLogic Administration Server Pod, then see enabling WLST access when local and remote ports do not match for an additional required setup step.
  3. Be sure to review the port forward notes and warnings first, and then run a port forwarding command.
  4. Use the WebLogic Server Administration Console, the Remote Console, or WLST with the port forwarding command’s local address.
  5. Finally, terminate port forwarding.

Externally exposing administrative, RMI, or T3 capable WebLogic channels using a Kubernetes NodePort, load balancer, port forwarding, or a similar method can create an insecure configuration. For more information, see External network access security.

Set up Administration Server network channels for port forward access

To enable a kubectl port-forward command to communicate with a WebLogic Administration Server Pod, the operator must modify the Administration Server configuration to add network channels (Network Access Points) with a localhost address for each existing administration protocol capable port. This behavior depends on your version and domain resource configuration:

  • If Istio is not enabled on the domain or for Istio enabled domains running Istio 1.10 and later, this behavior is configurable on the domain resource using the domain.spec.adminServer.adminChannelPortForwardingEnabled domain resource attribute.

    For details about this attribute, run the kubectl explain domain.spec.adminServer.adminChannelPortForwardingEnabled command or see the domain resource schema.

  • If WLST access is required for Istio-enabled domains running Istio versions prior to 1.10, you must add an additional network channel to the WebLogic Administration Server configured with the following attributes:

    • Protocol defined as t3.
    • Listen address defined with localhost. (Note: Setting the address to localhost is solely for self-documenting purposes. The address can be set to any value, and the operator will override it to the required value.)
    • Listen port. Note: Choose a port value that does not conflict with any ports defined in any of the additional network channels created for use with Istio versions prior to v1.10. For more details, see Added network channels for Istio versions prior to v1.10.
    • Enable HTTP protocol for this network channel.
    • Do NOT set an external listen address or external listen port.

For Istio-enabled domains running Istio versions prior to 1.10, if console only access is required, then it is not necessary to add an additional network channel to the WebLogic Administration Server.

For example, here is a snippet of a WebLogic domain config.xml file for channel PortForward for the Administration Server.

<server>
  <name>admin-server</name>
  <network-access-point>
    <name>PortForward</name>
    <protocol>t3</protocol>
    <listen-address>localhost</listen-address>
    <listen-port>7890</listen-port>
    <http-enabled-for-this-protocol>true</http-enabled-for-this-protocol>
  </network-access-point>
</server>

For Model in Image (MII) and Domain in Image (DII), here is a snippet model configuration for channel PortForward for the Administration Server.

topology:
    ...
    Server:
        'admin-server':
            ListenPort: 7001
            NetworkAccessPoint:
                PortForward:
                    Protocol: 't3'
                    ListenAddress: 'localhost'
                    ListenPort: '7890'
                    HttpEnabledForThisProtocol: true

If your domain is already running, and you have made configuration changes, then you will need to rerun its introspector job and ensure that the admin pod restarts for the configuration changes to take effect.

If Istio is not enabled on the domain or for Istio enabled domains running Istio 1.10 and later, when administration channel port forwarding is enabled, the operator automatically adds the following network channels (also known as Network Access Points) to the WebLogic Administration Server Pod:

Description Channel Name Listen Address Port Protocol
When there’s no administration port or administration channels configured, and a non-SSL default channel exists internal-t3 localhost Server listening port t3
When there’s no administration port or administration channels configured, and an SSL default channel exists internal-t3s localhost Server SSL listening port t3s
When an administration port is enabled internal-admin localhost WebLogic administration port admin
When one or more custom administration channels are configured internal-admin${index} (where ${index} is a number that starts with 1 and increases by 1 for each custom administration channel) localhost Custom administration port admin

Port forward to an Administration Server Pod

If you have set up WebLogic Administration Server network channels for port forward access, then you can run a kubectl port-forward command to access such a channel. The command:

  • By default, opens a port of your choosing on localhost on the machine where you run the command.
  • Forwards traffic from this location to an address and port on the pod. For administrative access, you need to forward to a port on the Administration Server Pod
    that accepts administration traffic.

Port forwarding occurs as long as the remote pod and the command are running. If you exit the command, then the forwarding stops and the local port and address is freed. If the pod cycles or shuts down, then the forwarding also stops and the command must be rerun after the pod recovers in order for the forwarding to restart.

The kubectl port-forward command has the following syntax:

kubectl port-forward K8S_RESOURCE_TYPE/K8S_RESOURCE_NAME [options] LOCAL_PORT:REMOTE_PORT_ON_RESOURCE

For detailed usage, see port-forward in the Kubernetes reference documentation and run kubectl port-forward -h.

For examples, notes, and warnings, see the Port forward example and Port forward notes and warnings.

Port forward example

For example, if you have a WebLogic domain with:

  • Domain UID domain1
  • Namespace mynamespace
  • An Administration Server named admin-server listening on non-SSL listen port 7001
  • No administration port or administration channels configured on the Administration Server

And, you have set up WebLogic Administration Server network channels for port forward access for this domain, then you can run either of the following commands to forward local port 32015 to the Administration Server Pod:

kubectl port-forward pods/domain1-admin-server -n mynamespace 32015:7001

or

kubectl port-forward service/domain1-admin-server -n mynamespace 32015:7001

The command output will be similar to the following:

Forwarding from 127.0.0.1:32015 -> 7001

In this example:

  • You can access the WebLogic Server Administration Console at the http://localhost:32015/console URL by using a browser on the machine where you run the kubectl port-forward command.

  • You can use WLST on the machine where you run the kubectl port-forward command to connect to t3://localhost:32015 as shown:

    $ $ORACLE_HOME/oracle_common/common/bin/wlst.sh

    Initializing WebLogic Scripting Tool (WLST) ...

Welcome to WebLogic Server Administration Scripting Shell

Type help() for help on available commands

wls:/offline> connect('myadminuser','myadminpassword','t3://localhost:32015')
Connecting to t3://localhost:32015 with userid myadminuser ...
Successfully connected to Admin Server "admin-server" that belongs to domain "base_domain".

Warning: An insecure protocol was used to connect to the server.
To ensure on-the-wire security, the SSL port or Admin port should be used instead.

wls:/base_domain/serverConfig/> exit()

Port forward notes and warnings

  • Security warning: A port-forward connection can expose a WebLogic T3 or administrative channel outside the Kubernetes cluster. For domain security considerations, see External network access security.

  • Working with administration or SSL ports: If a WebLogic administration port is configured and enabled on the Administration Server, then you will need to forward to this port instead of its pod’s other ports. In this case, the Administration Console access requires using the secure https protocol and WLST access requires using t3s protocol. Similarly, if forwarding to an SSL port, then this requires using the https and t3s protocols for Administration Console and WLST access respectively.

  • Recovering from pod failures and restarts: A port-forward connection terminates after the pod instance fails or restarts. You can rerun the same command to establish a new forwarding session and resume forwarding.

  • Using WLST when the local port differs from the remote port: If you are setting up WLST access and your port forwarding local port is not going to be the same as the port number on the WebLogic Administration Server Pod, then see Enabling WLST access when local and remote ports do not match for an additional required setup step.

  • Specifying a custom local IP address for port forwarding:

    Specifying a custom local IP address for port forwarding allows you to run WLST or your browser on a different machine than the port forward command.

    You can use the --address option of the kubectl port-forward command to listen on specific IP addresses instead of, or in addition to, localhost.

    The --address option only accepts numeric IP addresses or localhost (comma-separated) as a value.

    For example, to enable Administration Console access at http://my-ip-address:32015/console, the command:

    kubectl port-forward --address my-ip-address pods/domain1-admin-server -n mynamespace 32015:7001

    See kubectl port-forward -h for help and examples.

  • Optionally let kubectl port-forward choose the local port:

    If you don’t specify a local port in your port forward command, for example:

    kubectl port-forward pods/domain1-admin-server -n mynamespace :7001

    Then the command finds a local port number that is not in use, and its output is similar to:

    Forwarding from 127.0.0.1:63753 -> 7001

    And the Administration Console is accessible using the http://localhost:63753/console URL.

Enabling WLST access when local and remote ports do not match

If a local (forwarded) port number is not the same as the administration port number, then WLST access will not work by default and you may see a BEA-000572 RJVM error in the Administration Server logs:

<Aug 30, 2021 9:33:24,753 PM GMT> <Error> <RJVM> <BEA-000572> <The server rejected a connection attempt JVMMessage from: '-2661445766084484528C:xx.xx.xx.xxR:-5905806878036317188S:domain1-admin-server:domain1:admin-server' to: '0B:xx.xx.xx.xx:[-1,-1,32015,-1,-1,-1,-1]' cmd: 'CMD_IDENTIFY_REQUEST', QOS: '102', responseId: '-1', invokableId: '-1', flags: 'JVMIDs Sent, TX Context Not Sent, 0x1', abbrev offset: '114' probably due to an incorrect firewall configuration or administrative command.><

To work around the problem, configure the JAVA_OPTIONS environment variable for your Administration Server with the -Dweblogic.rjvm.enableprotocolswitch=true system property in your domain resource YAML. For more information on this switch, refer to MOS ‘Doc 860340.1’.

Terminating port forwarding

A port-forward connection is active only while the kubectl port-forward command is running.

You can terminate the port-forward connection by pressing CTRL+C in the terminal where the port forward command is running.

If you run the command in the background, then you can kill the process with the kill -9 <pid> command. For example:

$ ps -ef | grep port-forward
oracle   27072 25312  1 21:45 pts/3    00:00:00 kubectl -n mynamespace port-forward pods/domain1-admin-server 32015:7001
oracle   27944 11417  0 21:45 pts/1    00:00:00 grep --color=auto port-forward
$ kill -9 27072