Port travis config to github actions

.github/workflows/main.yml

@@ -0,0 +1,33 @@
+name: Build docker images
+
+# Controls when the workflow will run
+on:
+  # Triggers the workflow on push or pull request events but only for the master branch
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  build:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-20.04
+    steps:
+      # Checks out repository under $GITHUB_WORKSPACE, so we can access it
+      - uses: actions/checkout@v2
+
+      # Runs build script
+      - name: Run build script
+        run: |
+          # always push
+          export PUSH=true
+          # if this is a push to master and not a PR, also push latest - GITHUB_HEAD_REF is only set for PRs
+          if [ -z ${GITHUB_HEAD_REF+x} ] && [ "$GITHUB_REF" == "refs/heads/master" ]; then export PUSH=latest; fi
+          # log into quay.io so we can push
+          echo "$QUAY_PASSWORD" | docker login quay.io -u "$QUAY_USER" --password-stdin
+          # build and push all components. try to pull and re-use layers from images for all parent commits.
+          'CACHE_FROM=$(git rev-list HEAD -n1 --parents | cut -d" " -f 2-) ./build'
+