Channyboy / ci.docker

Docker Hub images

There are three different Open Liberty Docker image sets available on Docker Hub:

1. Official Images: available here, these are re-build automatically anytime something changes in the layers below, and updated with new Open Liberty binaries as they become available (generally every 4 weeks). The Dockerfiles can be found in the official directory. There are tags with different combinations of Java and Operating System versions.

2. Daily Images: available here, these are daily images from the daily Open Liberty binaries. The scripts used for this image can be found here.

3. Community Images: available here, these are images using Red Hat's Universal Base Image as the Operating System. The Dockerfiles can be found in the community directory.

Building an application image

According to Docker's best practices you should create a new image (FROM open-liberty) which adds a single application and the corresponding configuration. You should avoid configuring the image manually, after it started (unless it is for debugging purposes), because such changes won't be present if you spawn a new container from the image.

Even if you docker save the manually configured container, the steps to reproduce the image from open-liberty will be lost and you will hinder your ability to update that image.

The key point to take-away from the sections below is that your application Dockerfile should always follow a pattern similar to:

FROM open-liberty:kernel

# Add my app and config
COPY --chown=1001:0  Sample1.war /config/dropins/
COPY --chown=1001:0  server.xml /config/

# Optional functionality
ARG SSL=true
ARG MP_MONITORING=true

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

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

Enterprise Functionality

This section describes the optional enterprise functionality that can be enabled via the Dockerfile during build time, by setting particular build-arguments (ARG) and calling RUN configure.sh. Each of these options trigger the inclusion of specific configuration via XML snippets, described below:

• HTTP_ENDPOINT
  • Decription: 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
  • Decription: Check the health of the environment using Liberty feature mpHealth-1.0 (implements MicroProfile Health).
  • XML Snippet Location: mp-health-check.xml
• MP_MONITORING
  • Decription: 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.
• TLS or SSL (SSL is being deprecated)
  • Decription: Enable Transport Security in Liberty by adding the transportSecurity-1.0 feature (includes support for SSL).
  • XML Snippet Location: keystore.xml.
• IIOP_ENDPOINT
  • Decription: 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
  • Decription: Add configuration properties for an JMS endpoint.
  • XML Snippet Location: jms-ssl-endpoint.xml when SSL is enabled. Otherwise, jms-endpoint.xml
• OIDC
  • Decription: Enable OpenIdConnect Client function by adding the openidConnectClient-1.0 feature.
  • XML Snippet Location: oidc.xml
• OIDC_CONFIG
  • Decription: 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.

To customize one of the built-in XML snippets, make a copy of the snippet from Github and edit it locally. Once you have completed your changes, use the COPY command inside your Dockerfile to copy the snippet into /config/configDropins/overrides. It is important to note that you do not need to set build-arguments (ARG) for any customized XML snippets. The following Dockerfile snippet is an example of how you should include the customized snippet.

COPY --chown=1001:0 <path_to_customized_snippet> /config/configDropins/overrides

Session Caching

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. One example is Hazelcast In-Memory Data Grid. Enabling Hazelcast session caching retrieves the Hazelcast client libraries from the hazelcast/hazelcast Docker 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 Docker 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 Docker image
COPY --from=hazelcast/hazelcast --chown=1001:0 /opt/hazelcast/lib/*.jar /opt/ol/wlp/usr/shared/resources/hazelcast/

# Instruct configure.sh to copy the client topology hazelcast.xml
ARG HZ_SESSION_CACHE=client

# 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

Updating common files

Currently the common folder contains the docker-server and README.md files. When making changes to these files first make the changes in common and then run sync-master.sh to copy these files to the directories the files need to be in for the Docker build. All the files need to be checked into git. Docker won't allow you to copy files from the parent directory structure, so this allows us to update once, rather than having to update in multiple locations.