Update Dockerfile.rhel8 to fix the postgresql upgrade issue from v12 to v13.

[dinaharan]

Updated docker file to set the POSTGRESQL_PREV_VERSION environment variable for postgresql version 13.

Here is the OLD PR: #451

[phracek]

@dinaharan Why do you create a new PR? It should be enough to update the old one. Is there any reason?

[dinaharan]

phracek

I noticed some difference in Dockerfile from my fork to the current and I don't want to update in the old file an that's reason created the new PR with updated Dockerfile content.

[phracek]

[test-all]

[phracek]

The change itself looks good to me and tests are passing.

[phracek]

@dinaharan As @pkubatrh mentioned the upgrade tests are not run for RHEL8 https://github.com/sclorg/postgresql-container/blob/master/test/run_test#L655. It would be nice to also fix https://github.com/sclorg/postgresql-container/blob/master/test/run_upgrade_test to support test_upgrade also for RHEL8.

[phracek]

This allows to upgrade into version 13. Please modify also run_upgrade_test so we have covered test suite.

[hhorak]

[test]

[hhorak]

Looking at the code, I'm worried the upgrade that is handled based on $POSTGRESQL_PREV_VERSION variable only works on RHSCL (RHEL-7), does't it? The SCL path is hardcoded in the function for example:
https://github.com/sclorg/postgresql-container/blob/705b6558/src/root/usr/share/container-scripts/postgresql/common.sh#L295

Also, I don't see we'd install postgresql-upgrade package anywhere, which would be needed for the upgrade to proceed. Or do I miss something here?

[hhorak]

Anyway, #452 that requests upgrade to work is a valid request, we just need to do more than what this PR currently changes. At minimum, install postgresql-upgrade package and also change the common.sh to work with non-scl packages.

[phracek]

[test-all]

[phracek]

@dinaharan Can you please provide updated #456 (comment). Otherwise we are not able to merge this pull request. Also please rebase this pull request agains master. THank you.