add initialization example script

[aushacker]

A simple example showing how to configure a database with some test data.

When using ephemeral storage the database name specified by POSTGRESQL_DATABASE must be different from that created in the user provided script, otherwise the container will crash loop. This is due to the default scripts hard failing when trying to create a database that the user supplied init script has already created.

See issue #296 for narrative (known problem).

[phracek]

[test-all]

[phracek]

Container tests are passing. Unfortunately, I am not a database expert. @hhorak @fila43 WDYT?
As soon as @fila43 or @hhorak approve this pull request, we can merge it.

@aushacker Do we have a test for it? If not please create at least one.

[aushacker]

@phracek Have had a look through the available tests, none of them seem to match the required procedure.

What is needed to test would be something like:

1. Build base image
2. Create a new image, layering in postgresql-init/initialize.sh
3. Spin up the image from 2 in podman/docker
4. Use a postgresql client to connect and query the quotes database

How does that fit in with the current testing procedure?

[fila43]

I do not see any problem with proposed example

[fila43]

[test-all]

[phracek]

@aushacker Thank you for this pull request. Please do following steps:

• rebase it agains the master
• call make clean-versions
• call make generate-all which is mandatory, because of distgen check is failing. It means that generated changes are different then we expect it.