open-liberty

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Official Open Liberty image.

GitHub repo: https://github.com/OpenLiberty/ci.docker

Library reference

This content is imported from the official Docker Library docs, and is provided by the original uploader. You can view the Docker Hub page for this image at https://hub.docker.com/images/open-liberty

Supported tags and respective Dockerfile links

Quick reference

Overview

The images in this repository contain Open Liberty. For more information about Open Liberty, see the Open Liberty Website site.

Image User

This image runs by default with USER 1001 (non-root), as part of group 0. Please make sure you read below to set the appropriate folder and file permissions.

Updating folder permissions

All of the folders accessed by Open Liberty have been given the appropriate permissions, but if your extending Dockerfile needs permission to another location you can simply temporarily switch into root and provide the needed permissions, example:

USER root
RUN mkdir -p /myFolder && chown -R 1001:0 /myFolder
USER 1001

Updating file permissions

You have to make sure that all the artifacts you are copying into the image (via COPY or ADD) have the correct permissions to be read and executed by user 1001 or group 0, because the ownership of the file is changed to be root:0 when transferring into the docker image.

You have a few options for doing this: before copying the file, during copy, or after copy.

Updating permissions before copying

Since the ownership of the file will change to root:0, you can simply set the permissions for the owner’s group to be able to read/execute the artifact (i.e. the middle digit of a chmod command). For example, you can do chmod g+rx server.xml to ensure your server.xml can be read and executed by group 0, as well as any artifacts such as the application’s EAR or WAR file, JDBC driver, or other files that are placed on the image via COPY or ADD.

Updating permissions during copy

If you’re using Docker v17.09.0-ce and newer you can take advantage of the flag --chown=<user>:<group> during either ADD or COPY. For example: COPY --chown=1001:0 jvm.options /config/jvm.options. This is the preferred approach as you don’t need to worry about changing permissions before calling docker build and you also do not duplicate layers in the resulting image.

Updating permissions after copy

If you need your Dockerfile to work with older versions of Docker CE and don’t want to pre-process the permissions of the files you can temporarily switch into root to change the permissions of the needed files. For example:

USER root
RUN chown 1001:0 /config/jvm.options
RUN chown 1001:0 /output/resources/security/ltpa.keys
USER 1001

Please note that this pattern will duplicate the docker layers for those artifacts, which can heavily bloat your resulting docker image (depending on the size of the artifact). So it is recommended to set the permissions before or during copy.

Tags

There are multiple tags available in this repository.

The kernel image contains the Liberty kernel and can be used as the basis for custom built images that contain only the features required for a specific application. For example, the following Dockerfile starts with this image, copies in the server.xml that lists the features required by the application.

FROM open-liberty:kernel
COPY --chown=1001:0  Sample1.war /config/dropins/
COPY --chown=1001:0  server.xml /config/

The microProfile1 image contains the features required to implement Eclipse MicroProfile 1.3. The webProfile8 image contains the features required for Java EE8 Web Profile compliance. The javaee8 image adds the features required for Java EE8 Full Platform compliance. The javaee8 image is also tagged with latest. The webProfile7 image contains the features required for Java EE7 Web Profile compliance. The javaee7 image adds the features required for Java EE7 Full Platform compliance. The springBoot1 and springBoot2 images contain the features required for running Spring Boot 1.5 and 2.0 applications.

There are also additional images for different JVM combinations. Currently there are tags for java8 only, but there are two variants one based on IBM Java and Ubuntu and the other based on the IBM small footprint Java which is based on alpine linux. The naming structure for the variants is tag-javaversion-vandor/variant. This leads to webProfile8-java8-ibmsfj as one. At this time the full list of images are found in the Supported tags and respective Dockerfile links section above.

Usage

The images are designed to support a number of different usage patterns. The following examples are based on the Java EE8 Liberty application deployment sample and assume that DefaultServletEngine.zip has been extracted to /tmp and the server.xml updated to accept HTTP connections from outside of the container by adding the following element inside the server stanza (if not using one of the pre-packaged server.xml files with our tags):

<httpEndpoint host="*" httpPort="9080" httpsPort="-1"/>

Application Image

It is a very strong best practice to create an extending Docker image, we called it the application image, that encapsulates an application and its configuration. This creates a robust, self-contained and predictable Docker image that can span new containers upon request, without relying on volumes or other external runtime artifacts that may behave different over time.

If you want to build the smallest possible WebSphere Liberty application image you can start with our kernel tag, add your artifacts, and run configure.sh to grow the set of features to be fit-for-purpose. Please see our GitHub page for more details.

Enabling Enterprise functionality

The Open Liberty images have a set of built-in XML snippets that enable and configure enterprise functionality such as session cache and monitoring. These are toggled by specific ARGs in your application image Dockerfile and configured via the configure.sh script. Please see the instructions on our GitHub page for more information.

Using volumes for configuration

This pattern can be useful for quick experiments / early development (i.e. I just want to run the application as I iterate over it), but should not be used for development scenarios that involve different teams and environments - for these cases the Application Image pattern described above is the way to go.

When using volumes, an application file can be mounted in the dropins directory of this server and run. The following example starts a container in the background running a .WAR file from the host file system with the HTTP and HTTPS ports mapped to 80 and 443 respectively.

$ docker run -d -p 80:9080 -p 443:9443 \
	    -v /tmp/DefaultServletEngine/dropins/Sample1.war:/config/dropins/Sample1.war \
	    open-liberty:webProfile8

When the server is started, you can browse to http://localhost/Sample1/SimpleServlet on the Docker host.

Note: If you are using the boot2docker virtual machine on OS X or Windows, you need to get the IP of the virtual host by using the command boot2docker ip instead of by using localhost.

For greater flexibility over configuration, it is possible to mount an entire server configuration directory from the host and then specify the server name as a parameter to the run command. Note: This particular example server configuration provides only HTTP access.

```console
$ docker run -d -p 80:9080 \
  -v /tmp/DefaultServletEngine:/config \
  open-liberty:webProfile8
```

Using springBoot images

The springBoot images introduce capabilities specific to the support of Spring Boot applications, including the springBootUtility used to separate Spring Boot applications into thin applications and dependency library caches. To elaborate these capabilities this section assumes the standalone Spring Boot 2.0.x application hellospringboot.jar exists in the /tmp directory.

  1. A Spring Boot application JAR deploys to the dropins/spring directory within the default server configuration, not the dropins directory. Liberty allows one Spring Boot application per server configuration. You can create a Spring Boot application layer over this image by adding the application JAR to the dropins/spring directory. In this example we copied hellospringboot.jar from /tmp to the same directory containing the following Dockerfile.

    FROM open-liberty:springBoot2
    COPY --chown=1001:0 hellospringboot.jar /config/dropins/spring/
    

    The custom image can be built and run as follows.

    $ docker build -t app .
    $ docker run -d -p 8080:9080 app
    
  2. The springBoot images provide the library cache directory, lib.index.cache, which contains an indexed library cache created by the springBootUtility command. Use lib.index.cache to provide the library cache for a thin application.

    You can use the springBootUtility command to create thin application and library cache layers over a springBoot image. The following example uses docker staging to efficiently build an image that deploys a fat Spring Boot application as two layers containing a thin application and a library cache.

    FROM open-liberty:springBoot2 as staging
    COPY --chown=1001:0 hellospringboot.jar /staging/myFatApp.jar
    RUN springBootUtility thin \
       --sourceAppPath=/staging/myFatApp.jar \
       --targetThinAppPath=/staging/myThinApp.jar \
       --targetLibCachePath=/staging/lib.index.cache
    FROM open-liberty:springBoot2
    COPY --from=staging /staging/lib.index.cache /lib.index.cache
    COPY --from=staging /staging/myThinApp.jar /config/dropins/spring/myThinApp.jar
    

    For Spring Boot applications packaged with library dependencies that rarely change across continuous application updates, you can use the capabilities mentioned above to to share library caches across containers and to create even more efficient docker layers that leverage the docker build cache.

Providing your own keystore/truststore

When an open-liberty image starts, it can generate a Liberty server XML snippet in /config/configDropins/defaults/keystore.xml that specifies a keyStore stanza with a generated password. This causes Open Liberty to generate a default keystore and truststore with a self-signed certificate when it starts. Images can request this by setting:

ENV KEYSTORE_REQUIRED "true"

When providing your own keystore/truststore, this default behavior can be disabled by adding:

ENV KEYSTORE_REQUIRED "false"

It is good practice to place the keystore customization in /config/configDropins/defaults/keystore.xml even when not generated since this makes it easier to find and makes moving to the websphere-liberty docker image simpler.

Using IBM JRE Class data sharing

The IBM JRE provides a feature Class data sharing which offers transparent and dynamic sharing of data between multiple Java Virtual Machines running on the same host by using shared memory backed by a file. When running the Liberty Docker image, it looks for the file at /opt/ol/wlp//output/.classCache. To benefit from Class data sharing, this location needs to be shared between containers either through the host or a data volume container.

Taking the application image from example 3 above, containers can share the host file location (containing the shared cache) /tmp/open-liberty/classCache as follows:

docker run -d -p 80:9080 -p 443:9443 \
    -v /tmp/open-liberty/classCache:/opt/ol/wlp/output/.classCache app

Or, create a named data volume container that exposes a volume at the location of the shared file:

docker run -v /opt/ol/wlp//output/.classCache \
    --name classcache open-liberty true

Then, run the Open Liberty image with the volumes from the data volume container classcache mounted as follows:

docker run -d -p 80:9080 -p 443:9443 --volumes-from classcache app

Running Open Liberty in read-only mode

Liberty writes to two different directories when running: /opt/ol/wlp//output and /logs. In order to run the Liberty image in read-only mode these may be mounted as temporary file systems. If using the provided image, the keystore will be generated on initial start up in the server configuration. This means that the server configuration directory either needs to be read-write or the keystore will need to be built into the image. In the example command /config is mounted as a read-write volume.

docker run -d -p 80:9080 -p 443:9443 \
    --tmpfs /opt/ol/wlp//output --tmpfs /logs -v /config --read-only \
    open-liberty:webProfile8

Relationship between Open Liberty and WebSphere Liberty

WebSphere Liberty is a commercial distribution of Open Liberty. There is an official docker image for websphere-liberty. The websphere-liberty docker image predates the open-liberty one, so to make it simpler to move from open-liberty to websphere-liberty (or vice versa) the images are broadly compatible. It should be possible to move from one to the other with a simple FROM clause change. Some considerations for moving between them:

Open Liberty installs into `/opt/ol` rather than `/opt/ibm`.
Use the `/config` folder for accessing the server configuration.
Use the `/output` folder for accessing the server output.
When adding your own SSL configuration use the `/config/configDropins/defaults/keystore.xml`.

License

View license information for the software contained in this image.

As with all Docker images, these likely also contain other software which may be under other licenses (such as Bash, etc from the base distribution, along with any direct or indirect dependencies of the primary software being contained).

Some additional license information which was able to be auto-detected might be found in the repo-info repository’s open-liberty/ directory.

As for any pre-built image usage, it is the image user’s responsibility to ensure that any use of this image complies with any relevant licenses for all software contained within.

library, sample, open-liberty