FAB-5700 Couchdb crashes with mounted volume

The CouchDB image has a volume at
/opt/couchdb/data which it uses to
store it's persistent data.  If you
try to attach an external volume for this
and either the host path does not exist or
the permissions for the host path are
incorrect, CouchDB will crash and the
container will fail to start.

This comes down to a permissions issue
coupled with "helpful" behavior from
the Docker daemon.

The issue is that if the host path does not
exist, the Docker daemon will create the host
path but will create it under the same user
as the daemon is running (which is typically
root).  The current Dockerfile then changes
the user to couchdb but now which then
runs all subsequent commands as couchdb.
Although a volume is created after this,
permissions are not / cannot be
properly set.

So this fix removes the use of the
USER command in the Dockerfile,
changes ownership of the volume
in the docker-entrypoint script
and then finally uses su-exec to
start CouchDB as the couchdb user

Change-Id: If8ac0e34b13d447d68b99408cebcfbf93d257c0f
Signed-off-by: Gari Singh <gari.r.singh@gmail.com>

images/couchdb/Dockerfile.in

@@ -74,8 +74,6 @@ RUN chmod +x /docker-entrypoint.sh \
 WORKDIR /opt/couchdb
 EXPOSE 5984 4369 9100
 
-USER couchdb
-
 VOLUME ["/opt/couchdb/data"]
 
 ENTRYPOINT ["tini", "--", "/docker-entrypoint.sh"]

images/couchdb/docker-entrypoint.sh

@@ -44,4 +44,6 @@ if [ "$1" = '/opt/couchdb/bin/couchdb' ]; then
 	sleep 1
 fi
 
-exec "$@"
+chown -R couchdb:couchdb /opt/couchdb/data
+
+su-exec couchdb "$@"