docker-wildfly-embedded

A Docker container for Wildfly that allows configuration injection when booting the container. The container uses confd for generating a jboss-cli script that injects the configuration. The advantage of using confd is that it has many backends you can use, making it more versatile than using e.g. consul-template.

This is simple proof of concept to demonstrate how one could configure a default immutable Wildfly container, that would be usable in multiple environments (e.g. dev, test, UAT, staging, production, etc.), without having to 'hard-code' configuration into containers. I believe containers should adhere to the 12 factor principles, and should not be purpose built for a specific environment.

How it works

A new Wildfly container is generated using docker build. This build adds and pre-configures resources like JDBC drivers. These can be used/referenced to from other configuration. The build also adds confd and a TOML configuration + template for confd. A custom start script is used by the container to start Wildfly. Checkout the Dockerfile to see how the container is constructed.

The first thing this script does it use confd to generate a jboss-cli CLI script. In this script all runtime configuration to be injected into Wildfly is put. The configuration is retrieved from any backend that confd supports (e.g. environment variables, etcd, consul, zookeeper, etc.). The second thing the start script does is start jboss-cli and run an embedded Wildfly container in management mode. This means the server is started, and can be configured, but doesn't accept any requests on the public and/or management interfaces. It then uses the generated CLI script to configure the Wildfly server. As the CLI script ends, the server is automatically stopped. In the third and final step the start script starts the Wildfly container in stand-alone mode, as the official jboss/wildfly container does.

So it's kind of a 4 stage rocket:

1. The container is built, and all needed resources are added and preconfigured (as long as they're not environment specific, e.g. JDBC drivers)
2. At container start confd generates a jboss-cli script with all specific configurations
3. jboss-cli is started with the generated CLI script from step 1. This starts the Wildfly server in embedded mode and configures environment specific resources (e.g. LDAP, datasources, JavaMail sessions, security domains, etc.)
4. Wildfly is started in standalone mode, just like the official Wildfly container does

Using this sample application

Start a Consul server instance

docker run -d --net=host --name=consul gliderlabs/consul-server -bootstrap -advertise 192.168.99.100

Here 192.168.99.100 is my boot2docker virtualbox instance

Prepare testdata in Consul

curl -X PUT -d '{ "name":"testDS", "type":"mysql", "host":"db.example.com", "port":"3306", "database":"example", "username": "user1", "password":"s3cr3t" }' http://192.168.99.100:8500/v1/kv/myapp/datasources/testDS
curl -X PUT -d '{ "name":"anotherDS", "type":"postgresql", "host":"db2.example.com", "port":"12345", "database":"pgsample", "username":"pgsql1", "password":"s3cr3t" }' http://192.168.99.100:8500/v1/kv/myapp/datasources/anotherDS

or simply use Consul's web GUI.

Please note that the JSON format of the datasource definition needs to conform to a predetermined standard in order to be able to use it in the confd template. Check out config-server.cli.tmpl to see how the JSON values are parsed.

Start Wildfly

docker build -t gntry/wildfly .
docker run -p 8080:8080 -p 9990:9990 gntry/wildfly

See your configuration

Navigate to the Wildfly management console, and see your configuration in action:

Additional notes

This example will be updated with more Wildfly resources in the near future. E.g. A LDAP security realm and security domain will be added, as well as a JavaMail session, JMS/MQ resources, etc.

As you can see the actual start command for Wildfly is passed in through the CMD instruction in the Dockerfile. This means that by default Wildfly is started, but you could start bash or simply cat the generated CLI script as well.

For instance try:

docker run gntry/wildfly cat /tmp/config-server.cli
docker run -it gntry/wildfly /bin/bash
docker run -it gntry/wildfly /opt/jboss/wildfly/bin/jboss-cli.sh