=== [1] PG_VERSION — the datadir's own record of its major
Error response from daemon: No such container: docmost-postgres
docker: invalid spec: :/d: empty section between colons

Run 'docker run --help' for more information
=== [2] the engine's REFUSAL, verbatim (the whole point of this leg)
Error response from daemon: No such container: docmost-postgres
=== [3] container state

error: no such object: docmost-postgres
=== [4] the version binary in the image
Error response from daemon: No such container: docmost-postgres
(cannot exec — not running)