CI/CD with Singularity, Gitlab CI and Singularity Registry

A singularity registry is a dockerhub-like interface for sharing containers. With the sregistry client you can push/pull singularity containers into a singularity registry (public or private).

The following tutorial use a docker image with sregistry and singularity 2.6 installed (sysmso/singularity-ci).

sregistry-cli is available here : https://singularityhub.github.io/sregistry-cli/

How to upload container to sregistry with Gitlab CI

Example of .gitlab-ci.yml to build and push a container named container.simg, based on a Singularity recipe file into a sregistry :

image: sysmso/singularity-ci
 
stages:
   - build
   - deploy
 
singularity-image:
   stage: build
   script:
      - singularity build container.simg Singularity
   artifacts:
     paths:
      - container.simg
 
 deploy:
  stage: deploy
   script:
   - source /sregistry_file
   - echo $SREGISTRY_FILE > ~/.sregistry
   - sregistry push container.simg --name apc/tp-singu:latest --tag tuto

You have to register 3 variables in Gitlab CI in order to use this method :

SREGISTRY_HOSTNAME : URL of the registry

SREGISTRY_TOKEN : Sregistry Token

SREGISTRY_USERNAME : username in the registry

For security purpose you may want to protect these variables in Gitlab.