CODEWITHSUNDEEP
dockerdockerfile
Joël Craenhals
Joël Craenhals

Reputation: 475

Docker: modify files during image creation

I'm creating a Docker image for Atlassian JIRA. Dockerfile can be found here: https://github.com/joelcraenhals/docker-jira/blob/master/Dockerfile

However I want to enable the HTTPS connector on the Tomcat server inside the Docker image during image creation so that the server.xml file is configured during image creation.

How can I modify a certain file in the container?

Best regards,

Upvotes: 2

Views: 2672

Answers (2)

Eugen Mayer
Eugen Mayer

Reputation: 9944

Alternative a) I would say you are going the wrong path here. You do not want to do this during image creation, but rather during the entrypoint.

It is very common and best practise in docker to configure the service during the first container start e.g. seed the database, generate passwords and seeds and, as in you case, generate configuration based on templates.

Usually those configuration files are either controlled by ENV variables you pass on to docker run or rather in your docker-compose.yml, in more complex environments the source of the configuration variables can be consul or etcd.

For your example, e.g. you could introduce a ENV variable 'USE_SSL' and then either use sed in your entrypoint to replace something in the server.xml when it is set, but since you need much more, like setting the revers_proxy domain and things, you should go with tiller : https://github.com/markround/tiller

Create a server.xml.erb file, place the variables you want to be dynamic, use if conditions if you want to exclude a section if USE_SSL is not set, and let tiller use ENVIRONMENT as a datasources.

Alternative b) If you really want to stay with the "on image build" concept ( not recommended ) you should use the so called build_args https://docs.docker.com/engine/reference/commandline/build/

Add this to your docker file

ARG USE_SSL

RUN /some_script_you_created_to_generate_server_xml.sh $USE_SSL

You still need to have a bash/whatever script some_script_you_created_to_generate_server_xml.sh which takes the args, and creates by conditions, whatever you want. Tiller though will be much more convenient when stuff gets bigger (compared to running some seds/awks)

and then, when building the image, you could use `docker build . --build-arg USE_SSL=no -t yourtag

Upvotes: 1

Mateusz Moneta
Mateusz Moneta

Reputation: 1640

You need to extend this image with your custom config file, write your own Dockerfile with following content:

FROM <docker-jira image name>:<tag>

COPY <path to the server.xml on your computer, relative to Dockerfile dir> <path to desired location of server.xml inside the container>

After that you need to build and run your new image:

docker build . --tag <name of your image>
docker run <name of your image>

Upvotes: 0

Related Questions