Update postgresql testing script (#10906)

- Use sytest:bionic. Sytest:latest is two years old (do we want
  CI to push out latest at all?) and comes with Python 3.5, which we
  explictly no longer support. The script now runs under PostgreSQL 10
  as a result.
- Advertise script in the docs
- Move pg testing script to scripts-dev directory
- Write to host as the script's exector, not root

A few changes to make it speedier to re-run the tests:

- Create blank DB in the container, not the script, so we don't have to
  `initdb` each time
- Use a named volume to persist the tox environment, so we don't have to
  fetch and install a bunch of packages from PyPI each time

Co-authored-by: reivilibre <olivier@librepush.net>

2 files changed, 24 insertions, 7 deletions

diff --git a/docker/Dockerfile-pgtests b/docker/Dockerfile-pgtests
index 3bfee845c6..92b804d193 100644
--- a/docker/Dockerfile-pgtests
+++ b/docker/Dockerfile-pgtests
@@ -1,6 +1,6 @@
 # Use the Sytest image that comes with a lot of the build dependencies
 # pre-installed
-FROM matrixdotorg/sytest:latest
+FROM matrixdotorg/sytest:bionic
 
 # The Sytest image doesn't come with python, so install that
 RUN apt-get update && apt-get -qq install -y python3 python3-dev python3-pip
@@ -8,5 +8,23 @@ RUN apt-get update && apt-get -qq install -y python3 python3-dev python3-pip
 # We need tox to run the tests in run_pg_tests.sh
 RUN python3 -m pip install tox
 
-ADD run_pg_tests.sh /pg_tests.sh
-ENTRYPOINT /pg_tests.sh
+# Initialise the db
+RUN su -c '/usr/lib/postgresql/10/bin/initdb -D /var/lib/postgresql/data -E "UTF-8" --lc-collate="C.UTF-8" --lc-ctype="C.UTF-8" --username=postgres' postgres
+
+# Add a user with our UID and GID so that files get created on the host owned
+# by us, not root.
+ARG UID
+ARG GID
+RUN groupadd --gid $GID user
+RUN useradd --uid $UID --gid $GID --groups sudo --no-create-home user
+
+# Ensure we can start postgres by sudo-ing as the postgres user.
+RUN apt-get update && apt-get -qq install -y sudo
+RUN echo "user ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+
+ADD run_pg_tests.sh /run_pg_tests.sh
+# Use the "exec form" of ENTRYPOINT (https://docs.docker.com/engine/reference/builder/#entrypoint)
+# so that we can `docker run` this container and pass arguments to pg_tests.sh
+ENTRYPOINT ["/run_pg_tests.sh"]
+
+USER user
diff --git a/docker/run_pg_tests.sh b/docker/run_pg_tests.sh
index 1fd08cb62b..58e2177d34 100755
--- a/docker/run_pg_tests.sh
+++ b/docker/run_pg_tests.sh
@@ -10,11 +10,10 @@ set -e
 # Set PGUSER so Synapse's tests know what user to connect to the database with
 export PGUSER=postgres
 
-# Initialise & start the database
-su -c '/usr/lib/postgresql/9.6/bin/initdb -D /var/lib/postgresql/data -E "UTF-8" --lc-collate="en_US.UTF-8" --lc-ctype="en_US.UTF-8" --username=postgres' postgres
-su -c '/usr/lib/postgresql/9.6/bin/pg_ctl -w -D /var/lib/postgresql/data start' postgres
+# Start the database
+sudo -u postgres /usr/lib/postgresql/10/bin/pg_ctl -w -D /var/lib/postgresql/data start
 
 # Run the tests
 cd /src
 export TRIAL_FLAGS="-j 4"
-tox --workdir=/tmp -e py35-postgres
+tox --workdir=./.tox-pg-container -e py36-postgres "$@"