TL;DR: I would like to use on a self-hosted Actions runner (itself a docker container on my docker engine) specific docker images to build artefacts that I would move between the build phases, and end with a standalone executable (not a docker container to be deployed). I do not know how to use docker containers as "building engines" in Actions.
Details: I have a home project consisting of a backend in Go (cross compiled to a standalone binary) and a frontend in Javascript (actually a framework: Quasar).
I develop on my laptop in Windows and use GitHub as the SCM.
The manual steps I do are:
build a static version of the frontend which lands in a directory spa
copy that directory to the backend directory
compile the executable that embeds the spa directory
copy (scp) this executable to the final destination
For development purposes this works fine.
I now would like to use Actions to automate the whole thing. I use docker based self-hosted runners (tcardonne/github-runner).
My problem: the containers do a great job isolating the build environment from the server they run on. They are however reused across build jobs and this may create conflicts. More importantly, the default versions of software provided by these containers is not the right (usually - latest) one.
The solution would be to run the build phases in disposable docker containers (that would base on the right image, shortening the build time as a collateral nice to have). Unfortunately, I do not know how to set this up.
Note: I do not want to ultimately create docker containers, I just want to use them as "building engines" and extract the artefacts from them, and share between the jobs (in my specific case - one job would be to build the front with quasar and generate a directory, the other one would be a compilation ending up with a standalone executable copied elsewhere)
Interesting premise, you can certainly do this!
I think you may be slightly mistaken with regards to:
They are however reused across build jobs and this may create conflicts
If you run a new container from an image, then you will start with a fresh instance of that container. Files, software, etc, all adhering to the original image definition. Which is good, as this certainly aids your efforts. Let me know if I have the wrong end of the stick in regards to the above though.
Base Image
You can define your own image for building, in order to mitigate shortfalls of public images that may not be up to date, or suit your requirements. In fact, this is a common pattern for CI, and Google does something similar with their cloud build configuration. For either approach below, you will likely want to do something like the following to ensure you have all the build tools you may
As a rough example:
FROM golang:1.16.7-buster
RUN apt update && apt install -y \
git \
make \
...
&& useradd <myuser> \
&& mkdir /dist
USER myuser
You could build and publish this with the following tag:
docker build . -t <containerregistry>:buildr/golang
It would also be recommended that you maintain a separate builder image for other types of projects, such as node, python, etc.
Approaches
Building with layers
If you're looking to leverage build caching for your applications, this will be the better option for you. Caching is only effective if nothing has changed, and since the projects will be built in isolation, it makes it relatively safe.
Building your app may look something like the following:
FROM <containerregistry>:buildr/golang as builder
COPY src/ .
RUN make dependencies
RUN make
RUN mv /path/to/compiled/app /dist
FROM scratch
COPY --from=builder /dist /dist
The gist of this is that you would start building your app within the builder image, such that it includes all the build deps you require, and then use a multi stage file to publish a final static container that includes your compiled source code, with no dependencies (using the scratch image as the smallest image possible ).
Getting the final files out of your image would be a bit harder using this approach, as you would have to run an instance of the container once published in order to mount the files and persist it to disk, or use docker cp to retrieve the files from a running container (not image) to your disk.
In Github actions, this would look like running a step that builds a Docker container, where the step can occur anywhere with docker accessibility
For example:
jobs:
docker:
runs-on: ubuntu-latest
steps:
...
- name: Build and push
id: docker_build
uses: docker/build-push-action#v2
with:
push: true
tags: user/app:latest
Building as a process
This one can not leverage build caching as well, but you may be able to do clever things like mounting a host npm cache into your container to aid in actions like npm restore.
This approach differs from the former in that the way you build your app will be defined via CI / a purposeful script, as opposed to the Dockerfile.
In this scenario, it would make more sense to define the CMD in the parent image, and mount your source code in, thus not maintaining a image per project you are building.
This would shift the responsibility of building your application from the buildtime of the image, to the runtime. Retrieving your code from the container would be doable through volume mounting for example:
docker run -v /path/to/src:/src /path/to/dist:/dist <containerregistry>:buildr/golang
If the CMD was defined in the builder, that single script would execute and build the mounted in source code, and subsequently publish to /dist in the container, which would then be persisted to your host via that volume mapping.
Of course, this applies if you're building locally. It actually becomes a bit nicer in a Github actions context if you wish to keep your build instructions there. You can choose to run steps within your builder container using something like the following suggestion
jobs:
...
container:
runs-on: ubuntu-latest
container: <containerregistry>:buildr/golang
steps:
- run: |
echo This job does specify a container.
echo It runs in the container instead of the VM.
name: Run in container
Within that run: spec, you could choose to call a build script, or enter the commands that might be present in the script yourself.
What you do with the compiled source is muchly up to you once acquired 👍
Chaining (Frontend / Backend)
You mentioned that you build static assets for your site and then embed them into your golang binary to be served.
Something like that introduces complications of course, but nothing untoward. If you do not need to retrieve your web files until you build your golang container, then you may consider taking the first approach, and copying the content from the published image as part of a Docker directive. This makes more sense if you have two separate projects, one for frontend and backend.
If everything is in one folder, then it sounds like you may just want to extend your build image to facilitate go and js, and then take the latter approach and define those build instructions in a script, makefile, or your run: config in your actions file
Conclusion
This is alot of info, I hope it's digestible for you, and more importantly, I hope it gives you some ideas as to how you can tackle your current issue. Let me know if you would like clarity in the comments
I have a docker image downloaded from docker hub and that contains pre-installed dependencies which I don't want. I want to find out all the dependencies + transitive dependencies that are installed from my "Dockerfile" on top of the docker hub base-image. I tried looking for an open source program to do this but I could not find anything that seems suitable.
You can try to build your own or simply if they share their source you can modified from them.
Sample of mysql docker source :
https://github.com/docker-library/mysql/tree/master/8.0
You can clone their repo and then modified the Dockerfile to your requirement.
But if their base image contain pre-installed that you dont want then you have to build your own.
Thanks for your attention, I've been facing this issue for a couple of days.
I've got a React/Express project from Create React App inside a Docker container.
Basically, I've got some JSON files that I need to get at docker runtime because I don't want to have different docker images, I'd like to have a single one.
When I retrieve the files and then run npm run build at docker runtime my code works fine.
But, the problem is that I want to run npm run build at docker build time. And my code is not being able to find the JSON files because they were not bundled by webpack.
This is the current way that I'm using to load the files
const artifact = require(`./${path.join(config.files.dir, `${file}.json`)}`);
How can I load these files after the webpack build?
Currently, I don't have any webpack config files.
Thanks in advance.
If I want to install code from a release version in Github in Docker, how can I do that taking up the least space possible in the image? Currently, I've done something like:
RUN wget https://github.com/some/repo/archive/v1.5.1.tar.gz¬
RUN tar -xvzf v1.5.1.tar.gz¬
WORKDIR /unzipped-1.5.1/¬
RUN make; make install
Issue here is the final image will have the downloaded tar, the unzipped version, and everything that gets created during make. I don't need the vast majority of this. How do I install my library in my image without keeping all of this extra data?
This is the textbook definition of the problem that the docker multi-stage build aims to solve.
The idea is to use a separate build with the dependencies and use that docker image to build the final product.
Note that this is available only in the new versions of Docker (17.05 onwards).
Is there a way to only download the dependencies but do not compile source.
I am asking because I am trying to build a Docker build environment for my bigger project.
The Idear is that during docker build I clone the project, download all dependencies and then delete the code.
Then use docker run -v to mount the frequently changing code into the docker container and start compiling the project.
Currently I just compile the code during build and then compile it again on run. The problem ist that when a dependencie changes I have to build from scratch and that takes a long time.
Run sbt's update command. Dependencies will be resolved and retrieved.