diff --git a/.github/workflows/deploy-docker.yml b/.github/workflows/deploy-docker.yml
index f79e29cb..c1d2b233 100644
--- a/.github/workflows/deploy-docker.yml
+++ b/.github/workflows/deploy-docker.yml
@@ -11,13 +11,14 @@ name: Deployment - Docker images
 
 on:
   push:
-    branches: ['release']
+    branches: ['release', 'feat/build_apptainer_images']
   workflow_dispatch:
 
 env:
   REGISTRY: ghcr.io
   NAMESPACE: openforcefield
 
+
 jobs:
   build-and-push-image:
     runs-on: ubuntu-latest
@@ -35,6 +36,35 @@ jobs:
       packages: write
 
     steps:
+      - name: Free disk space
+        run: |
+          sudo docker rmi $(docker image ls -aq) >/dev/null 2>&1 || true
+          sudo rm -rf \
+            /usr/share/dotnet /usr/local/lib/android /opt/ghc \
+            /usr/local/share/powershell /usr/share/swift /usr/local/.ghcup \
+            /usr/lib/jvm || true
+          echo "some directories deleted"
+          sudo apt install aptitude -y >/dev/null 2>&1
+          sudo aptitude purge aria2 ansible azure-cli shellcheck rpm xorriso zsync \
+            esl-erlang firefox gfortran-8 gfortran-9 google-chrome-stable \
+            google-cloud-sdk imagemagick \
+            libmagickcore-dev libmagickwand-dev libmagic-dev ant ant-optional kubectl \
+            mercurial apt-transport-https mono-complete libmysqlclient \
+            unixodbc-dev yarn chrpath libssl-dev libxft-dev \
+            libfreetype6 libfreetype6-dev libfontconfig1 libfontconfig1-dev \
+            snmp pollinate libpq-dev postgresql-client powershell ruby-full \
+            sphinxsearch subversion mongodb-org azure-cli microsoft-edge-stable \
+            -y -f >/dev/null 2>&1
+          sudo aptitude purge google-cloud-sdk -f -y >/dev/null 2>&1
+          sudo aptitude purge microsoft-edge-stable -f -y >/dev/null 2>&1 || true
+          sudo apt purge microsoft-edge-stable -f -y >/dev/null 2>&1 || true
+          sudo aptitude purge '~n ^mysql' -f -y >/dev/null 2>&1
+          sudo aptitude purge '~n ^php' -f -y >/dev/null 2>&1
+          sudo aptitude purge '~n ^dotnet' -f -y >/dev/null 2>&1
+          sudo apt-get autoremove -y >/dev/null 2>&1
+          sudo apt-get autoclean -y >/dev/null 2>&1
+          echo "some packages purged"
+
       - name: Checkout repository
         uses: actions/checkout@v3
 
@@ -58,12 +88,26 @@ jobs:
             type=semver,pattern={{major}}.{{minor}}
             type=semver,pattern={{version}}
             type=sha
+            ${{ github.sha }}
 
-      - name: Build and push Docker image
+      - name: Build Docker Image and Push
         uses: docker/build-push-action@v4
         with:
           context: .
           file: ${{ matrix.dockerfile }}
-          push: true
+          push: false # change to true after merge, but I don't want to mess anything up while testing
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+
+      - name: Setup Apptainer
+        uses: eWaterCycle/setup-apptainer@v2
+        with:
+          apptainer-version: 1.1.2
+
+      - name: Build Apptainer Image
+        run: singularity build ${{ matrix.image }}:$GITHUB_SHA.sif docker-daemon:${{ env.REGISTRY }}/${{ env.NAMESPACE }}/${{ matrix.image }}:${{ github.sha }}
+
+      - name: Push Apptainer Image
+        run: |
+          echo ${{ secrets.GITHUB_TOKEN }} | singularity remote login -u ${{ secrets.GHCR_USERNAME }} --password-stdin oras://ghcr.io
+          singularity push ${{ matrix.image }}:$GITHUB_SHA.sif oras://${{ env.REGISTRY }}/${{ env.NAMESPACE }}/${{ matrix.image }}:${{ github.sha }}-apptainer