add nightly build and push (#2297)

* add nightly build and push

* add date based nightly build tags

* only keep single multiarch image build and push

* add changelog

* add images to internal docs static files

* add docu for nightly builds

* remove unnecessary spaces

* update nightly repository

.github/workflows/nightly.yml

@@ -0,0 +1,39 @@
+name: Nightly builds
+
+on:
+  schedule: # Run every day at 03:00 UTC
+    - cron: '0 3 * * *'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out code
+      uses: actions/checkout@v3
+      with:
+        ref: master
+        fetch-depth: 0
+        fetch-tags: true
+
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v2
+
+    - name: Set up Docker Buildx
+      id: buildx
+      uses: docker/setup-buildx-action@v2
+
+    - name: Login to quay.io
+      uses: docker/login-action@v2
+      with:
+        registry: quay.io/oauth2-proxy
+        username: ${{ secrets.REGISTRY_USERNAME_NIGHTLY }}
+        password: ${{ secrets.REGISTRY_PASSWORD_NIGHTLY }}
+
+    - name: Build images
+      run: |
+        make docker-nightly-build
+
+    - name: Push images
+      run: |
+        make docker-nightly-push