.travis.yml

os:
- linux
dist: bionic
language: minimal

services:
- docker

stages:
# Execute upon PR or push to open PR
- name: build_image
  if: type = pull_request
# Execute only upon merge into master
- name: push_image
  if: type = push AND branch = master

jobs:
  include:
  - stage: build_image
    name: Build Docker image
    script:
    - |
      git diff --name-only "$TRAVIS_COMMIT_RANGE" | \
      grep ".*\/Dockerfile$" | \
      while read -r file ; do
        if git diff --compact-summary "$TRAVIS_COMMIT_RANGE" | grep "$file" | grep "(gone)"; then
            echo "Dockerfile '$file' was deleted. Not building."
            continue
        fi
        echo "Building image for Dockerfile '$file'..."
        travis_wait 60 docker build $(dirname "$file")
      done
  - stage: push_image
    name: Build image and push to Docker Hub
    script:
    - |
      git diff --name-only "$TRAVIS_COMMIT_RANGE" | \
      grep ".*\/Dockerfile$" | \
      while read -r file ; do
        # Skip if file was deleted
        if git diff --compact-summary "$TRAVIS_COMMIT_RANGE" | grep "$file" | grep "(gone)"; then
            echo "Dockerfile '$file' was deleted. Not building."
            continue
        fi
        # Extract tool name and version and sanitize according to Docker rules
        tool_name=$(dirname $(dirname "$file") | tr A-Z a-z | sed 's/[^a-z\-\_]//g')
        version=$(basename $(dirname "$file") | sed -e 's/[^a-zA-Z0-9\_\.\-]//g' -e 's/^[\.\-]//')
        remote="${DOCKER_ORGANIZATION}/${tool_name}:${version}"
        echo "Building image for Dockerfile '$file'..."
        travis_wait 60 docker build -t "$remote" $(dirname $file)
        echo "Pushing image to '$remote'..."
        echo "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
        docker push "$remote"
      done