Build docker image without docker installed

Question

Is it somehow possible to build images without having docker installed. On maven build of my project I'd like to produce docker image, but I don't want to force others to install docker on their machines.

I can think of some virtual box image with docker installed, but it is kind of heavy solution. Is there some way to build the image with some maven plugin only, some Go code or already prepared virtual box image for exactly this purpose?

It boils down to question how to use docker without forcing users to install anything. Either just for build or even for running docker images.

UPDATE

There are some, not really up to date, maven plugins for virtual machine provisioning with vagrant or with vbox. I have found article about building docker images without docker on basel So far I see two options either I can somehow build the images only or run some VM with docker daemon inside(which can be used not only for builds, but even for integration tests)

Answer 1

We can create Docker image without Docker being installed.

Jib Maven and Gradle Plugins

Google has an open source tool called Jib that is relatively new, but quite interesting for a number of reasons. Probably the most interesting thing is that you don’t need docker to run it - it builds the image using the same standard output as you get from docker build but doesn’t use docker unless you ask it to - so it works in environments where docker is not installed (not uncommon in build servers). You also don’t need a Dockerfile (it would be ignored anyway), or anything in your pom.xml to get an image built in Maven (Gradle would require you to at least install the plugin in build.gradle).

Another interesting feature of Jib is that it is opinionated about layers, and it optimizes them in a slightly different way than the multi- layer Dockerfile created above. Just like in the fat jar, Jib separates local application resources from dependencies, but it goes a step further and also puts snapshot dependencies into a separate layer, since they are more likely to change. There are configuration options for customizing the layout further.

Pls refer this link https://cloud.google.com/blog/products/gcp/introducing-jib-build-java-docker-images-better

For example with Spring Boot refer https://spring.io/blog/2018/11/08/spring-boot-in-a-container

Answer 2

Have a look at the following tools:

1. Fabric8-maven-plugin - http://maven.fabric8.io/ - good maven integration, uses a remote docker (openshift) cluster for the builds.
2. Buildah - https://github.com/containers/buildah - builds without a docker daemon but does have other pre-requisites.

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Fabric8-maven-plugin

The fabric8-maven-plugin brings your Java applications on to Kubernetes and OpenShift. It provides a tight integration into Maven and benefits from the build configuration already provided. This plugin focus on two tasks: Building Docker images and creating Kubernetes and OpenShift resource descriptors.

fabric8-maven-plugin seems particularly appropriate if you have a Kubernetes / Openshift cluster available. It uses the Openshift APIs to build and optionally deploy an image directly to your cluster.

I was able to build and deploy their zero-config spring-boot example extremely quickly, no Dockerfile necessary, just write your application code and it takes care of all the boilerplate.

Assuming you have the basic setup to connect to OpenShift from your desktop already, it will package up the project .jar in a container and start it on Openshift. The minimum maven configuration is to add the plugin to your pom.xml build/plugins section:

<plugin>
    <groupId>io.fabric8</groupId>
    <artifactId>fabric8-maven-plugin</artifactId>
    <version>3.5.41</version>
</plugin>

then build+deploy using

$ mvn fabric8:deploy

If you require more control and prefer to manage your own Dockerfile, it can handle this too, this is shown in samples/secret-config.

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Buildah

Buildah is a tool that facilitates building Open Container Initiative (OCI) container images. The package provides a command line tool that can be used to:

• create a working container, either from scratch or using an image as a starting point
• create an image, either from a working container or via the instructions in a Dockerfile
• images can be built in either the OCI image format or the traditional upstream docker image format
• mount a working container's root filesystem for manipulation
• unmount a working container's root filesystem
• use the updated contents of a container's root filesystem as a filesystem layer to create a new image
• delete a working container or an image
• rename a local container