Screw building Synapse docker image

just pull the build image from dockerhub

Author: David Robertson

.github/workflows/ci.yaml

@@ -14,8 +14,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - name: Prepare the Docker image for Synapse `develop`
-        run: test/before_test.sh
+#      When CI ran on BuildKite, we used to also run the following script to build a
+#      Synapse docker image from scratch.
+#      I leave it here for posterity and completeness.
+#      - name: Prepare the Docker image for Synapse `develop`
+#        run: test/before_test.sh
       - name: Setup services and launch tests
         run: docker-compose up --build --abort-on-container-exit
 

Dockerfile

@@ -1,7 +1,7 @@
 # A Dockerfile used for running tests.
 # This Dockerfile should work for other plug-ins, too.
 
-FROM matrixdotorg/synapse:latest
+FROM matrixdotorg/synapse:develop
 
 # Install extension.
 WORKDIR /data