DX-1586: Auto-update apt packages

Add workflow to auto-update apt packages by writing them to an `apt.json` file

.docker/Dockerfile

@@ -25,13 +25,10 @@ RUN addgroup --system --gid 1000 jekyll && \
 
 RUN apt-get clean && \
     apt-get update && \
-    apt-get \
-    --no-install-recommends \
-    install -y \
-    locales=2.28-10 \
-    default-jre=2:1.11-71 \
-    graphviz=2.40.1-6+deb10u1 \
-    fontconfig=2.13.1-2 && \
+    apt-get --no-install-recommends install -y jq && \
+    jq -r 'to_entries | .[] | .key + "=" + .value' /tmp/apt.json | xargs apt-get install -y --no-install-recommends && \
+    rm /tmp/apt.json && \
+    apt-get purge -y jq && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/*
 

.docker/apt.json

@@ -0,0 +1,6 @@
+{
+  "locales": "2.28-10",
+  "default-jre": "2:1.11-71",
+  "graphviz": "2.40.1-6+deb10u1",
+  "fontconfig": "2.13.1-2"
+}

.github/scripts/apt_update.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+JSON=$( cat apt.json )
+
+for PACKAGE in $( echo $JSON | jq -r 'keys | .[]' ); do
+	VERSION=$( apt-cache policy "$PACKAGE" | grep -oP '(?<=Candidate:\s)(.+)' )
+	JSON=$( echo $JSON | jq '.[$package] = $version' --arg package $PACKAGE --arg version $VERSION )
+done
+
+echo $JSON | python -m json.tool > apt.json

.github/workflows/apt-update.yml

@@ -0,0 +1,29 @@
+name: apt update
+on:
+  schedule:
+  - cron: "30 2 * * *"
+  workflow_dispatch:
+
+jobs:
+  apt-update:
+    timeout-minutes: 10
+    runs-on: ubuntu-20.04
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2.3.4
+
+    - name: Update dependencies
+      working-directory: .docker
+      run: |
+        sudo apt-get update
+        sh ${{ github.workspace }}/.github/scripts/apt_update.sh
+
+    - name: Create PR
+      uses: peter-evans/create-pull-request@v3
+      with:
+        commit-message: "Update apt.json"
+        branch: features/update-apt-json
+        title: Update apt packages
+        body: Updated apt.json
+        delete-branch: true
+        labels: dependencies, apt