👉 Prerequisites
If you are new to GitHub Actions, I suggest you to read these articles
As we discussed in previous articles, we can run our workflows in virtual machines by using operating systems that GitHub Actions provides as GitHub Hosted Runners.
Using Docker Container
We can use a docker container which will be installed on the the virtual machine & then instead of running directly on virtual machine, our workflow will runs on a particular container.
This can be an image from Docker Hub.
Docker Hub
Docker Hub is the platform which allows users to create, manage, and deliver their container applications. Docker Hub is the largest library of container images.
Link: Docker Hub
Once you click on an image (For example Node), you can see all the dockerfile links with the respective tags.
How to use ?
You have to provide the,
publisher-dockerhub-username : docker-image-tag with the image tag under the "container:"
- We can not use containers on windows and mac-os virtual machines.
- We can use containers only on ubuntu machines.
name: workflow-name
on: push
jobs:
job-name:
runs-on: ubuntu-latest
container:
image: dockerhub-username:docker-image-tag
Example:
name: container
on: push
jobs:
node-docker:
runs-on: ubuntu-latest
container:
image: node:14.15.0-alpine3.12
Also you can provide some other parameters like environment variables, ports & options...etc
name: container
on: push
jobs:
node-docker:
runs-on: ubuntu-latest
container:
image: node:14.15.0-alpine3.12
#env:
# ENV1: Available to this container only
#ports: To expose our container
#options: --cpus 1 --host
So in next figure you can confirm that steps are running inside the container we initialized with dockerhub image, instead of running directly on the virtual machine.
name: container
on: push
jobs:
node-docker:
runs-on: ubuntu-latest
container:
image: node:14.15.0-alpine3.12
steps:
- name: Log the node version
run: |
node -v
cat /etc/os-release
Here we echo the node version of the image and some operating system information of the docker container.
Output:
We can also specify multiple containers to run as services.
If you have an application to run multiple services, you might need multiple images to run in our virtual machine. Normally we use Docker-Compose to do something like that, **but in GitHub Actions we have a similar way to run this type of applications.
Running multiple docker containers in a job.
Instead of having container here, we can provide "services: "
We can give the services as docker-images under the "services:" and they run as separate containers in our virtual machine.
name: workflow-name
on: push
jobs:
job-name:
runs-on: ubuntu-latest
services:
service-name-1:
image: dockerhub-username:docker-image-1
ports:
- 3001:3000
service-name-2:
image: dockerhub-username:docker-image-2
ports:
- 4001:4000
steps:
- name: Get from service-1
run: http://localhost:3001/api/users
- name: Get from service-2
run: http://localhost:4001/api/items
- name: post a user example
run: "curl -x POST http://localhost:3001/api/user -H 'Content-Type: application/json' -d '{\"username"\: \"hello"\, \"address"\: "sampleaddress"}' "
Here it creates two containers for service-1 & service-2 inside our virtual machine
In order to communicate between those two containers, we can use the service-name as the host name in the app.
Running docker containers in individual steps.
In GitHub Actions, we can use different containers in different steps as well.
We can use "with:" key to provide inputs to this container in the particular step
We can give an entrypoint in with: key and override the entrypoint of the dockerfile
To find some entrypoints of the echo, node ...etc use this commands
Ex 1:
type -a echo
- Output - Entrypoint of echo in ubuntu:
echo is /bin/echo
Ex 2 :
type -a node
- Output - Entrypoint of node in ubuntu:
node is usr/local/bin/echo
Use this "type -a " command in ubuntu to find some Entrypoints of the installed tools & softwares.
Example:
name: container
on: push
jobs:
node-docker:
runs-on: ubuntu-latest
container:
image: node:14.15.0-alpine3.12
steps:
- name: Log the parent container node version
run: |
node -v
# Echo the node version of the parent container
- name: Log the step container node version
uses: docker://node:12.14.1-alpine3.10
with:
entrypoint: usr/local/bin/echo
args: -v
# Echo the node version of this step container based on this 12.14.1-alpine3.10 image
- name: Step with docker to echo a string
uses: docker://node:12.14.1-alpine3.10
with:
entrypoint: /bin/echo
args: Hello Docker !
Push the workflow file into the repository & check the Actions window of the repository
Outputs:
v14.15.0
v12.14.1
Hello Docker !
👉 What's Next?
Thank You
Hope you all enjoyed and learned something from this. Let me know your comments and suggestions in the discussion section.
👉 Visit me - https://mihinduranasinghe.com/
Top comments (1)
How do you run a container in the backgronud tha you have just built?
The basic idea is not to push image before doing at least smoke testing.