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Image process

Explains how Megalotron images' are built and used in production.

GitHub Registry​

Megalotron use its organisation's registry to host Docker Image.

We could use other solution like Docker Hub or ECR but it is more convenient to reduce the number of services used.

Process​

gh registry process schema

note

Each repository has credentials to push to Megalotron GitHub repository.

Password is stored as a secret named REGISTRY_TOKEN and the username is stored as REGISTRY_USERNAME.

Image convention​

Megalotron has multiple stack, to simplify its management, there's a semantic convention to follow.

  • An image shall be named following the convention megalotron/<stack>:<tag>.
  • Tag shall follow the official semantic versioning.
  • New release shall have a newer version than the previous one: v1.0.0 -> v1.0.1.
  • Production and develop version shall respectively be named main and dev.

Image name by stack​

StackTag
Dashboardmegalotron/dashboard
Backendmegalotron/backend
Sniffermegalotron/sniffer
Go FlowMetermegalotron/go-flow-meter

Guide​

Manually push an image to GitHub registry​

caution

You need to generate a Personal Access Token on GitHub so your Docker Engine can authenticate to the GitHub registry.

Of course, you also need a running Docker engine on your host.

Let's use as example the alpine docker image that we will push to the GitHub registry.

  1. Pull the image in your local Docker engine.
# Pull image
docker pull alpine

# Check if the image exist locally
docker image inspect alpine
#
# [
#    {
#        "Id": "sha256:04eeaa5f8c35b8206a15c12425498c37ecd2181e0ef202bea24a2382e4dd240f",
#...
note

You can use any image loaded in your local Docker engine. This may have been built by a Dockerfile or pulled from another registry.

  1. Tag the Alpine image to target the GitHub registry
docker tag alpine ghcr.io/megalotron/alpine:test
  1. Login to the GitHub registry
# Export your PAT into environment
export GHCR_PAT=<your generated personnal access token>

# Login to GitHub registry
echo $GHCR_PAT | docker login ghcr.io -u <your GH username> --password-stdin
  1. Push image to GitHub Registry
docker push ghcr.io/megalotron/alpine:test