• WebSphere Application Server Liberty and Containers
  • Container images
  • Building an application image
  • Build Variables
  • Security
  • OpenJ9 Shared Class Cache (SCC)
  • Logging
  • InstantOn
  • Session Caching
  • Applying interim fixes
  • Installing Liberty Features from local repository (19.0.0.8+)
    • Locally hosting feature repository
    • Using locally hosted feature repository in Dockerfile
• Known Issues
• Issues and Contributions
• License

• Our recommended set uses Red Hat's Universal Base Image (UBI) as the Operating System and are rebuilt periodically. They are available from IBM Container Registry (icr.io) and are listed here.
• Another set, using Ubuntu as the Operating System can be found on Docker Hub.

According to best practices for container images, you should create a new image (FROM icr.io/appcafe/websphere-liberty:) which adds a single application and the corresponding configuration. You should avoid configuring the container manually once it started, unless it is for debugging purposes, because such changes won't persist if you spawn a new container from the image.

Your application image template should follow a pattern similar to:

FROM icr.io/appcafe/websphere-liberty:kernel-java17-openj9-ubi

# Default setting for the verbose option. Set it to true to debug the application container image build failures
ARG VERBOSE=false

# Add Liberty server configuration including all necessary features
COPY --chown=1001:0  server.xml /config/

# Modify feature repository (optional)
# A sample is in the 'Getting Required Features' section below
COPY --chown=1001:0 featureUtility.properties /opt/ibm/wlp/etc/

# This script will add the requested XML snippets to enable Liberty features and grow the image to be fit-for-purpose using featureUtility.
RUN features.sh

# Add interim fixes (optional)
COPY --chown=1001:0  interim-fixes /opt/ibm/fixes/

# Add application
COPY --chown=1001:0  Sample1.war /config/dropins/

# This script will add the requested server configurations, apply any interim fixes and populate caches to optimize runtime
RUN configure.sh

This will result in a container image that has your application and configuration pre-loaded, which means you can spawn new fully-configured containers at any time.

The kernel tag provides just the bare minimum server. You can grow it to include the features needed by your application by invoking features.sh. Liberty features are downloaded from Maven Central repository by default. But you can specify alternatives using /opt/ibm/wlp/etc/featureUtility.properties:

remoteRepo.url=https://my-remote-server/secure/maven2
remoteRepo.user=operator
remoteRepo.password={aes}KM8dhwcv892Ss1sawu9R+

Refer to Repository and proxy modifications for more information.

This section describes the optional build variables that can be enabled via the Dockerfile during the build time, by setting particular build-argument (ARG) or environment variable (ENV) and calling RUN configure.sh. Each of these variables trigger the inclusion of specific configuration via XML snippets (except for VERBOSE and SKIP_FEATURE_INSTALL), described below:

• HZ_SESSION_CACHE
  • Description: Enable the persistence of HTTP sessions using JCache by adding the sessionCache-1.0 feature.
  • XML Snippet Location: hazelcast-sessioncache.xml
• SKIP_FEATURE_INSTALL
  • Description: Default setting is false. When set to true, Liberty features will not be installed using installUtility when configure.sh is run. This setting is not applicable when features.sh is run.
• TLS (SSL is deprecated)
  • Description: Enable Transport Security in Liberty by adding the transportSecurity-1.0 feature (includes support for SSL).
  • XML Snippet Location: keystore.xml.
• VERBOSE
  • Description: When set to true it outputs the commands and results to stdout from configure.sh. Otherwise, default setting is false and configure.sh is silenced.
• GENERATE_LTPA_KEYS_PASSWORD (26.0.0.5+)
  • Description: Automatically generates a secure random password for LTPA keys and exports it as the ltpa_keys_password environment variable. This prevents the LTPA service from failing with error CWWKS4118E when no LTPA keys password is configured.
  • Default: "true".
  • Note: If ltpa_keys_password is already set, automatic generation is skipped. Set to "false" to disable.

The following container image build variables are now deprecated and will be removed in a future release. You should stop using them:

• HTTP_ENDPOINT
  • Description: Add configuration properties for an HTTP endpoint.
  • XML Snippet Location: http-ssl-endpoint.xml when SSL is enabled. Otherwise http-endpoint.xml
• MP_HEALTH_CHECK
  • Description: Check the health of the environment using Liberty feature mpHealth-1.0 (implements MicroProfile Health).
  • XML Snippet Location: mp-health-check.xml
• MP_MONITORING
  • Description: Monitor the server runtime environment and application metrics by using Liberty features mpMetrics-1.1 (implements Microprofile Metrics) and monitor-1.0.
  • XML Snippet Location: mp-monitoring.xml
  • Note: With this option, /metrics endpoint is configured without authentication to support the environments that do not yet support scraping secured endpoints.
• IIOP_ENDPOINT
  • Description: Add configuration properties for an IIOP endpoint.
  • XML Snippet Location: iiop-ssl-endpoint.xml when SSL is enabled. Otherwise, iiop-endpoint.xml.
  • Note: If using this option, env.IIOP_ENDPOINT_HOST environment variable should be set to the server's host. See IIOP endpoint configuration for more details.
• JMS_ENDPOINT
  • Description: Add configuration properties for an JMS endpoint.
  • XML Snippet Location: jms-ssl-endpoint.xml when SSL is enabled. Otherwise, jms-endpoint.xml
• OIDC
  • Description: Enable OpenIdConnect Client function by adding the openidConnectClient-1.0 feature.
  • XML Snippet Location: oidc.xml
• OIDC_CONFIG
  • Description: Enable OpenIdConnect Client configuration to be read from environment variables.
  • XML Snippet Location: oidc-config.xml
  • Note: The following variables will be read: OIDC_CLIENT_ID, OIDC_CLIENT_SECRET, OIDC_DISCOVERY_URL.

Single Sign-On can be optionally configured by adding Liberty server variables in an xml file, by passing environment variables (less secure), or by passing Liberty server variables in through the Liberty operator. See SECURITY.md.

OpenJ9's SCC allows the VM to store Java classes in an optimized form that can be loaded very quickly, JIT compiled code, and profiling data. Deploying an SCC file together with your application can significantly improve start-up time. The SCC can also be shared by multiple VMs, thereby reducing total memory consumption.

WebSphere Liberty container images contain an SCC and (by default) add your application's specific data to the SCC at image build time when your Dockerfile invokes RUN configure.sh.

Note that currently some content in the SCC is sensitive to heap geometry. If the server is started with options that cause heap geometry to significantly change from when the SCC was created that content will not be used and you may observe fluctuations in start-up performance. Specifying a smaller -Xmx value increases the chances of obtaining a heap geometry that's compatible with the AOT code.

This feature can be controlled via the following variables:

• OPENJ9_SCC (environment variable)
  • Description: If "true", cache application-specific in an SCC and include it in the image. A new SCC will be created if needed, otherwise data will be added to the existing SCC.
  • Default: "true".
• TRIM_SCC (environment variable)
  • Description: If "true", the application-specific SCC layer will be sized-down to accomodate only the data populated during image build process. To allow the application to add more data to the SCC at runtime, set this variable to "false", but also ensure the SCC is not marked read-only. This can be done by setting the OPENJ9_JAVA_OPTIONS environment variable in your application Dockerfile like so: ENV OPENJ9_JAVA_OPTIONS="-XX:+IgnoreUnrecognizedVMOptions -XX:+IdleTuningGcOnIdle -Xshareclasses:name=openj9_system_scc,cacheDir=/opt/java/.scc,nonFatal -Dosgi.checkConfiguration=false". Note that OPENJ9_JAVA_OPTIONS is already defined in the base Liberty image dockerfile, but includes the readonly sub-option.
  • Default: "true".
• SCC_SIZE (environment variable)
  • Description: The size of the application-specific SCC layer in the image. This value is only used if TRIM_SCC is set to "false".
  • Default: "80m".
• WARM_ENDPOINT (environment variable)
  • Description: If "true", curl will be used to access the WARM_ENDPOINT_URL (see below) during the population of the SCC. This will increase the amount of information in the SCC and improve first request time in subsequent starts of the image.
  • Default: "true".
• WARM_ENDPOINT_URL (enviornment variable)
  • Description: The URL to access during SCC population if WARM_ENDPOINT is true.
  • Default: "localhost:9080/".
• WARM_OPENAPI_ENDPOINT (environment variable)
  • Description: (24.0.0.4+) If "true", curl will be used to access the WARM_OPENAPI_ENDPOINT_URL (see below) during the population of the SCC. This will increase the amount of information in the SCC and improve first request time in subsequent starts of the image.
  • Default: "true"
• WARM_OPENAPI_ENDPOINT_URL (enviornment variable)
  • Description: (24.0.0.4+) The URL to access during SCC population if WARM_OPENAPI_ENDPOINT is true.
  • Default: "localhost:9080/openapi"

It is important to be able to observe the logs emitted by WebSphere Liberty when it is running in a container. A best practice method would be to emit the logs in JSON and to then consume it with a logging stack of your choice.

Configure your WebSphere Liberty container image to emit JSON formatted logs to the console/standard-out with your selection of liberty logging events by providing the following environment variables to your WebSphere Liberty DockerFile.

For example:

//This example illustrates the use of all available logging sources.
ENV WLP_LOGGING_CONSOLE_FORMAT=JSON
ENV WLP_LOGGING_CONSOLE_LOGLEVEL=info
ENV WLP_LOGGING_CONSOLE_SOURCE=message,trace,accessLog,ffdc,audit

These environment variables can be set when running container as well. This can be achieved by using the run command's '-e' option to pass in an environment variable value.

docker run -d -p 80:9080 -p 443:9443 -e WLP_LOGGING_CONSOLE_FORMAT=JSON -e WLP_LOGGING_CONSOLE_LOGLEVEL=info -e WLP_LOGGING_CONSOLE_SOURCE=message,trace,accessLog,ffdc,audit websphere-liberty:latest

For more information regarding the configuration of WebSphere Liberty's logging capabilities see: https://www.ibm.com/support/knowledgecenter/en/SSD28V_liberty/com.ibm.websphere.wlp.core.doc/ae/rwlp_logging.html

Liberty InstantOn provides fast startup times for MicroProfile and Jakarta EE applications. With InstantOn, your applications can start in milliseconds, without compromising on throughput, memory, development-production parity, or Java language features.

View the guide on Containerizing, packaging, and running a Spring Boot application to learn how to use Liberty InstantOn with a Spring Boot application for faster startup.

The Liberty session caching feature builds on top of an existing technology called JCache (JSR 107), which provides an API for distributed in-memory caching. There are several providers of JCache implementations. The configuration for two such providers, Infinispan and Hazelcast, are outlined below.

1. Infinispan - One JCache provider is the open source project Infinispan, which is the basis for Red Hat Data Grid. Enabling Infinispan session caching retrieves the Infinispan client libraries from the Infinispan JCACHE (JSR 107) Remote Implementation maven repository, and configures the necessary infinispan.client.hotrod.* properties and the Liberty server feature sessionCache-1.0 by including the XML snippet infinispan-client-sessioncache.xml.

   • Setup Infinispan Service - Configuring Liberty session caching with Infinispan depends on an Infinispan service being available in your Kubernetes environment. It is preferable to create your Infinispan service by utilizing the Infinispan Operator. The Infinispan Operator Tutorial provides a good example of getting started with Infinispan in OpenShift.

   • Install Client Jars and Set INFINISPAN_SERVICE_NAME - To enable Infinispan functionality in Liberty, the container image author can use the Dockerfile provided below. This Dockerfile assumes an Infinispan service name of example-infinispan, which is the default used in the Infinispan Operator Tutorial. To customize your Infinispan service see Creating Infinispan Clusters. The INFINISPAN_SERVICE_NAME environment variable must be set at build time as shown in the example Dockerfile, or overridden at image deploy time.

     • TIP - If your Infinispan deployment and Liberty deployment are in different namespaces/projects, you will need to set the INFINISPAN_HOST, INFINISPAN_PORT, INFINISPAN_USER, and INFINISPAN_PASS environment variables in addition to the INFINISPAN_SERVICE_NAME environment variable. This is due to the Liberty deployment not having the access to the Infinispan service environment variables it requires.

   ### Infinispan Session Caching ###
   FROM icr.io/appcafe/websphere-liberty:kernel-java17-openj9-ubi AS infinispan-client
   
   # Install Infinispan client jars
   USER root
   RUN infinispan-client-setup.sh
   USER 1001
   
   FROM icr.io/appcafe/websphere-liberty:kernel-java17-openj9-ubi AS open-liberty-infinispan
   
   # Copy Infinispan client jars to Open Liberty shared resources
   COPY --chown=1001:0 --from=infinispan-client /opt/ibm/wlp/usr/shared/resources/infinispan /opt/ibm/wlp/usr/shared/resources/infinispan
   
   # Instruct configure.sh to use Infinispan for session caching.
   # This should be set to the Infinispan service name.
   # TIP - Run the following oc/kubectl command with admin permissions to determine this value:
   #       oc get infinispan -o jsonpath={.items[0].metadata.name}
   ENV INFINISPAN_SERVICE_NAME=example-infinispan
   
   # Uncomment and set to override auto detected values.
   # These are normally not needed if running in a Kubernetes environment.
   # One such scenario would be when the Infinispan and Liberty deployments are in different namespaces/projects.
   #ENV INFINISPAN_HOST=
   #ENV INFINISPAN_PORT=
   #ENV INFINISPAN_USER=
   #ENV INFINISPAN_PASS=
   
   # This script will add the requested XML snippets and grow image to be fit-for-purpose
   RUN configure.sh

   • Mount Infinispan Secret - Finally, the Infinispan generated secret must be mounted as a volume under the mount point of /platform/bindings/infinispan/secret/ on Liberty containers. The default location, for versions latest and 20.0.0.6+, of /platform/bindings/infinispan/secret/ can to be overridden by setting the LIBERTY_INFINISPAN_SECRET_DIR environment variable. When using the Infinispan Operator, this secret is automatically generated as part of the Infinispan service with the name of <INFINISPAN_CLUSTER_NAME>-generated-secret. For the mounting of this secret to succeed, the Infinispan Operator and Liberty must share the same namespace. If they do not share the same namespace, the INFINISPAN_HOST, INFINISPAN_PORT, INFINISPAN_USER, and INFINISPAN_PASS environment variables can be used instead(see the dockerfile example above). For an example of mounting this secret, review the volumes and volumeMounts portions of the YAML below.

   ...
       spec:
         volumes:
         - name: infinispan-secret-volume
           secret:
             secretName: example-infinispan-generated-secret
         containers:
         - name: servera-container
           image: ol-runtime-infinispan-client:1.0.0
           ports:
           - containerPort: 9080
           volumeMounts:
           - name: infinispan-secret-volume
             readOnly: true
             mountPath: "/platform/bindings/infinispan/secret/"
   ...
   

2. Hazelcast - Another JCache provider is Hazelcast In-Memory Data Grid. Enabling Hazelcast session caching retrieves the Hazelcast client libraries from the hazelcast/hazelcast container image, configures Hazelcast by copying a sample hazelcast.xml, and configures the Liberty server feature sessionCache-1.0 by including the XML snippet hazelcast-sessioncache.xml. By default, the Hazelcast Discovery Plugin for Kubernetes will auto-discover its peers within the same Kubernetes namespace. To enable this functionality, the container image author can include the following Dockerfile snippet, and choose from either client-server or embedded topology.

   ### Hazelcast Session Caching ###
   # Copy the Hazelcast libraries from the Hazelcast container image
   COPY --from=hazelcast/hazelcast --chown=1001:0 /opt/hazelcast/lib/*.jar /opt/ibm/wlp/usr/shared/resources/hazelcast/
   
   # Instruct configure.sh to copy the client topology hazelcast.xml
   ARG HZ_SESSION_CACHE=client
   
   # Default setting for the verbose option
   ARG VERBOSE=false
   
   # Instruct configure.sh to copy the embedded topology hazelcast.xml and set the required system property
   #ARG HZ_SESSION_CACHE=embedded
   #ENV JAVA_TOOL_OPTIONS="-Dhazelcast.jcache.provider.type=server ${JAVA_TOOL_OPTIONS}"
   
   ## This script will add the requested XML snippets and grow image to be fit-for-purpose
   RUN configure.sh

This section describes the process to apply interim fixes via the Dockerfile during build time, by adding the interim fix JAR files to /opt/ibm/fixes directory and calling RUN configure.sh. Interim fixes recommended by IBM, such as to resolve security vulnerabilities, are also included in the same directory.

Ensure that all features needed by your applications, apart from the ones that will be automatically added for the enterprise functionalities you selected, are specified prior to calling RUN configure.sh, since interim fixes should only be applied once needed features are installed.

# Add interim fixes (optional)
COPY --chown=1001:0  interim-fixes /opt/ibm/fixes/

# Default setting for the verbose option
ARG VERBOSE=false

# This script will add the requested XML snippets, grow image to be fit-for-purpose and apply interim fixes
RUN configure.sh

This section describes very simple way to speed up feature installation during builds of your images

The repository files can be downloaded from Fix Central.

To host feature repository on-premises one of the easiest solutions could be using nginx container image.

docker run --name repo-host -v /repo-host:/usr/share/nginx/html:ro -p 8080:80 -d nginx

You can mount and serve multiple zip files using a container volume mount, for example repo-host folder mounted from host to nginx container above.

You can place each zip archive in versioned folders, for example repo-host/${LIBERTY_VERSION}/repo.zip

You will need a hostname/IP and mapped port to generate FEATURE_REPO_URL, for example above port 8080 is used.

Using FEATURE_REPO_URL build argument it is possible to provide a link to a feature repo zip file containing all the features. You will also need to make sure to call RUN configure.sh in your Dockerfile

docker build --build-arg FEATURE_REPO_URL="http://wlprepos:8080/19.0.0.x/repo.zip"

You can also set it through Dockerfile

FROM icr.io/appcafe/websphere-liberty:kernel-java17-openj9-ubi
ARG FEATURE_REPO_URL=http://wlprepos:8080/19.0.0.x/repo.zip
ARG VERBOSE=false
RUN configure.sh

Note: This feature requires a curl command to be in the container image. Some base images do not provide curl. You can add it before calling confiure.sh this way:

FROM icr.io/appcafe/websphere-liberty:kernel-java17-openj9-ubi
USER root
RUN apt-get update && apt-get install -y curl
USER 1001
ARG FEATURE_REPO_URL=http://wlprepos:8080/19.0.0.x/repo.zip
ARG VERBOSE=false
RUN configure.sh

For the list of known issues related to images, see the Known Issues section for Open Liberty.

For issues relating specifically to the Dockerfiles and scripts, please use the GitHub issue tracker. For more general issue relating to IBM WebSphere Application Server Liberty you can get help through the WASdev community or, if you have production licenses for WebSphere Application Server, via the usual support channels. We welcome contributions following our guidelines.

The Dockerfiles and associated scripts found in this project are licensed under the Apache License 2.0.