Example using GitLab to build a custom .net 5.0 SDK image using kaniko. We use kaniko to build the container in runtime this makes it so the building doesn’t require access to the docker daemon. This allows to utilize the normal runners and don’t have to enable privileged mode in docker.

.gitlab-ci.yml

stages:
    - build:dotnet

default:
  image:
    name: gcr.io/kaniko-project/executor:debug
    entrypoint: [""]

.job_template: 
  script: &script_definition
    - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
    - /kaniko/executor -c $CI_PROJECT_DIR -f $DOCKER_FILE -d $CI_REGISTRY_IMAGE:$CI_JOB_NAME --build-arg USERNAME=$TFS_USERNAME --build-arg PASSWORD=$TFS_PASSWORD
  rules: &rules_definition
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
      when: always

# Job Templates
.build_and_deploy_dotnet: &build_and_deploy_dotnet
  stage: build:dotnet
  script: *script_definition
  rules: *rules_definition

# Builds
dotnet-5:
  <<: *build_and_deploy_dotnet
  variables:
    DOCKER_FILE: $CI_PROJECT_DIR/src/dotnet/Dockerfile.dotnet-sdk5.0

Dockerfile.dotnet-sdk5.0

# escape=`

FROM mcr.microsoft.com/dotnet/sdk:5.0 

COPY deploy.ps1 /deploy.ps1
COPY remote.ps1 /remote.ps1
COPY replace.ps1 /replace.ps1