Manage WebLogic domains


Important considerations for WebLogic domains in Kubernetes

Be aware of the following important considerations for WebLogic domains running in Kubernetes:

  • Domain Home Location: The WebLogic domain home location is determined by the domain resource domainHome and domainHomeInImage fields. If you are using 3.0.0-rc1, these same fields are used, if specified; otherwise, a default location is determined by the domainHomeSourceType setting. The domainHomeSourceType field is not available in releases before 3.0.0-rc1.

    • If the domain resource domainHome field is not specified and domainHomeSourceType is Image (the default), then the operator will assume that the domain home is a directory under /u01/oracle/user_projects/domains/, and report an error if no domain is found or more than one domain is found.
    • If the domain resource domainHome field is not specified and domainHomeSourceType is PersistentVolume, then the operator will assume that the domain home is /shared/domains/DOMAIN_UID.
    • Finally, if the domain resource domainHome field is not specified and the domainHomeSourceType is FromModel, then the operator will assume that the domain home is /u01/domains/DOMAIN_UID.

    Oracle strongly recommends storing an image containing a WebLogic domain home (domainHomeSourceType is Image) as private in the registry (for example, Oracle Cloud Infrastructure Registry, Docker Hub, and such). A Docker image that contains a WebLogic domain has sensitive information including keys and credentials that are used to access external resources (for example, the data source password). For more information, see WebLogic domain in Docker image protection.

  • Log File Locations: The operator can automatically override WebLogic domain and server log locations using configuration overrides. This occurs if the domain resource logHomeEnabled field is explicitly set to true, or if logHomeEnabled isn’t set and domainHomeSourceType is set to PersistentVolume. When overriding, the log location will be the location specified by the logHome setting.

  • Listen Address Overrides: The operator will automatically override all WebLogic domain default, SSL, admin, or custom channel listen addresses (using situational configuration overrides). These will become domainUID followed by a hyphen and then the server name, all lower case, and underscores converted to hyphens. For example, if domainUID=domain1 and the WebLogic Server name is Admin_Server, then its listen address becomes domain1-admin-server.

  • Domain, Cluster, Server, and Network-Access-Point Names: WebLogic domain, cluster, server, and network-access-point (channel) names must contain only the characters A-Z, a-z, 0-9, -, or _. This ensures that they can be converted to meet Kubernetes resource and DNS1123 naming requirements. (When generating pod and service names, the operator will convert configured names to lower case and substitute a hyphen (-) for each underscore (_).)

  • Node Ports: If you choose to expose any WebLogic channels outside the Kubernetes cluster using a NodePort, for example, the administration port or a T3 channel to allow WLST access, you need to ensure that you allocate each channel a unique port number across the entire Kubernetes cluster. If you expose the administration port in each WebLogic domain in the Kubernetes cluster, then each one must have a different port number. This is required because NodePorts are used to expose channels outside the Kubernetes cluster.

    Exposing administrative, RMI, or T3 capable channels using a Kubernetes NodePort can create an insecure configuration. In general, only HTTP protocols should be made available externally and this exposure is usually accomplished by setting up an external load balancer that can access internal (non-NodePort) services. For more information, see T3 channels.

  • Host Path Persistent Volumes: If using a hostPath persistent volume, then it must be available on all worker nodes in the cluster and have read/write/many permissions for all container/pods in the WebLogic Server deployment. Be aware that many cloud provider’s volume providers may not support volumes across availability zones. You may want to use NFS or a clustered file system to work around this limitation.

  • Security Note: The USER_MEM_ARGS environment variable defaults to in all WebLogic Server pods and the WebLogic introspection job. It can be explicitly set to another value in your domain resource YAML file using the env attribute under the serverPod configuration.

  • JVM Memory and Java Option Arguments: The following environment variables can be used to customize the JVM memory and Java options for both the WebLogic Server Managed Servers and Node Manager instances:

    • JAVA_OPTIONS - Java options for starting WebLogic Server
    • USER_MEM_ARGS - JVM memory arguments for starting WebLogic Server
    • NODEMGR_JAVA_OPTIONS - Java options for starting a Node Manager instance
    • NODEMGR_MEM_ARGS - JVM memory arguments for starting a Node Manager instance

    For more information, see Domain resource.

The following features are not certified or supported in this release:

  • Whole server migration
  • Consensus leasing
  • Node Manager (although it is used internally for the liveness probe and to start WebLogic Server instances)
  • Multicast
  • Multitenancy
  • Production redeployment
  • Mixed clusters (configured servers targeted to a dynamic cluster)

For up-to-date information about the features of WebLogic Server that are supported in Kubernetes environments, see My Oracle Support Doc ID 2349228.1.

Creating and managing WebLogic domains

You can locate a WebLogic domain either in a persistent volume (PV) or in a Docker image. For examples of each, see the WebLogic Server Kubernetes Operator samples.

If you want to create your own Docker images, for example, to choose a specific set of patches or to create a domain with a specific configuration or applications deployed, then you can create the domain custom resource manually to deploy your domain. This process is documented in this sample.

Modifying domain configurations

You can modify the WebLogic domain configuration for Domain in PV, Domain in Image, and Model in Image before deploying a domain resource:

When the domain is in a persistent volume, you can use WLST or WDT to change the configuration.

For Domain in Image and Domain in PV you can use configuration overrides.

Configuration overrides allow changing a configuration without modifying its original config.xml or system resource XML files, and supports parameterizing overrides so that you can inject values into them from Kubernetes Secrets. For example, you can inject database user names, passwords, and URLs that are stored in a secret.

For Model in Image you use Runtime Updates.

About the domain resource

For more information, see Domain resource.

Managing lifecycle operations

You can perform lifecycle operations on WebLogic Servers, clusters, or domains. See Starting and stopping and Restarting servers.

Scaling clusters

The operator let’s you initiate scaling of clusters in various ways: