Plone faster up than postgresql dbinit

[jensens]

If we're in a RelStorage environment Postgresql needs time for it initial dbinit.

Docker unfortunately removed to wait for a healthcheck, it only checks if a container is up, so we can not wait for it.

Now, Plone is starting up, because before postgres states its running before dbinit and while dbinit RelStorage tries to create the tables and stored procedures needed.
Postgres, after finished with dbinit, restarts itself. In Plone/RelStorage now the initialization is eventually only half done. Then Plone tries to connect to a partly created structure and fails.
dbinit is fast as well, mostly under 2-5s.

I propose to delay startup of Plone in case if Relstorage is used based on an environment variable. default 5s.
dinit runs once, so after initialization the variable can be set to 0s for the cluster.

Or are better ideas around?

[stevepiercy]

I have run into this myself. Here are two discussions that I found helpful.

• How to determine when new container is truly "ready" docker-library/postgres#146
• https://stackoverflow.com/a/63011266/2214933