docker-grails
Grails in Docker Container. This allows you to run grails like it has been installed on your host OS without actually installing all the developer tools on your OS. Cool!
Creates a docker container for specific grails versions.
Stack
The docker build does the following:
- Uses Ubuntu Trusty (14.04.x)
- Uses Oracle JDK 7
- Grails via gvm
Using the container
The environment is primarily used to launch a container that contains grails so you can either run grails inside the container for development, testing, and/or creating deployable WAR archives.
Versions
Different containers have been created for different grails versions. Here's a sample list of versions that are built:
- latest - usually updated to correspond to the latest grails version release
- x.x - uses the newest minor version for the major version specified
Grails major versions tags such as 2.1 and 2.2 uses the newest version for that branch. So, for example, grails:2.1 will use 2.1.5
Launching Grails
To run grails:
# launch the latest version of grails
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails grails
# launch a specific major version of grails
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails:2.3 grails run-app
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails:2.2 grails run-app
By mapping the project directory into the container using -v option, you can development under your host IDE.
Since the entire command line is so long, you can set an alias to run grails:
#set alias
alias grails="docker run -it -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails grails"
#Launch grails just using running grails
grails run-app
Running Grails Interactively
Run grails interactively so you can issue multiple commands without having to keep launching new runtime containers and recompiling and reinstalling plugins every single time:
# in order versions of grails
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails grails interactive
# in newer versions of grails, grails will run interactively when no args are given
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails grails
Start a Bash Shell Instead of Launching Grails
Want a bash shell into the container so you can do some setups instead of launching grails?
# override entrypoint
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails bash
Caching Grails Work Files
Since grails by default sets its work directory to your $USER_HOME/.grails, you will experience the case where every time you launch grails, it will need to re-install all the grails plugins and compile all the files again. This is useful if we're running tests on a CI server, but not very efficient when developing and writing code.
To speed this up, you can set the grails work directory to be inside your /app so that the cached files are stored and can be reused when launching new containers:
# override grails work dir
docker run -i -t -p 8080:8080 --rm -v $PWD:/app onesysadmin/grails grails -Dgrails.work.dir=/app/.grails
A better way to cache project related data separate from other projects is to set the project files in your project's BuildConfig.groovy. The settings appear to be part of the default settings generated in BuildConfig.groovy of a new project as well.
// In your BuildConfig.groovy project file
grails.project.class.dir = "target/classes"
grails.project.test.class.dir = "target/test-classes"
grails.project.test.reports.dir = "target/test-reports"
grails.project.work.dir = "target/work"
In fact, if you do this, you shouldn't need to set grails.work.dir.
This is great for CI / Jenkins build environments since all the project dependencies, plugins, and compiled outputs are located in your build workspace so it won't really affect other projects and it's easy to clean as well.
Unfortunately, in newer versions of Grails where maven repository is used to download jar dependencies, the maven cache uses a different setting and is stored in a separate directory, usually $USER_HOME/.m2/repository. To set this, set the environment variable GRAILS_DEPENDENCY_CACHE_DIR to your docker run command:
docker run -i -t -p 8080:8080 --rm -v $PWD:/app -e GRAILS_DEPENDENCY_CACHE_DIR=/app/.m2/repository onesysadmin/grails grails
This environment variable is currently only recognized in Grails 2.4.x image. Some older Grails versions do not make use of maven dependency management and resolution, so it's not set.
If you like, you can set this in your project BuildConfig.groovy by setting the grails.dependency.cache.dir config parameter. However, you can also set this in the environment variable.
Setting the JAVA_OPTS environment
The containers sets some basic default settings for java memory options like the heap size and the permagen size. If you require more memory or need to add extra options, you can either set the java options via grail's own environment variable or override the JAVA_OPTS environment when launching the docker container:
docker run -i -t -p 8080:8080 --rm -v $PWD:/app -e JAVA_OPTS "<new java options>" onesysadmin/grails grails
Testing and Continuous Integration
For continuous integration or to run your tests under a CI server like Jenkins, you can create a Jenkins project that is capable of launching docker instances. You can then create a Dockerfile that Jenkins can use to test or deploy your app container. Your build/test script might look something like the following:
#!/bin/bash
# test the app first to see if it passes
# create app-specific container beforehand if additional dependencies are required
# use your own container to run the tests if that's the case
docker run -i -t -v $PWD:/app onesysadmin/grails grails test-app
# If tests pass, let's create the war archive and build the deployment container
docker run -i -t -v $PWD:/app onesysadmin/grails grails war app.war
docker build -t myorg/myapp:1.1.1 .
# push out the docker container build to a repository
docker push myorg/myapp
A sample Dockerfile to build your grails web app would be something like the following:
# use a tomcat server container or your app specific container with tomcat optionally installed
FROM tutum/tomcat:8.0
ENV CATALINA_OPTS -Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms512m -Xmx1300m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:+CMSClassUnloadingEnabled -XX:+UseConcMarkSweepGC
EXPOSE 8080
# place app into tomcat app (alternatively, place it into ROOT for root webapp)
ADD app.war /tomcat/webapps
CONTRIBUTING
Want to fix/enhance the codebase or add more grails versions to be repo?
- Fork this repository
- Add your code changes
- Submit a pull request to this repository
Once approved and merged, it will be added to Docker Hub to be built.