Add support for CentOS / RHEL 8

[nmaludy]

To go along with StackStorm/st2#4761

Once this is done and there are CentOS 8 packages available, we can work to get this implemented in Ansible.

Things to handle:

• Mongodb 4.0
• Node 10
• CentOS 8 vs RHEL 8
• Removed some unused packs which were installed in EL7
• Mistral and Postgres no longer installed
• Python3 install numbered version

Updates for EL8:

• RabbitMQ on RHEL 8 requires: sudo yum -y module enable perl:5.26
• Currently need the rabbit packagecloud repo:

# Install rabbit from packagecloud
  curl -s https://packagecloud.io/install/repositories/rabbitmq/rabbitmq-server/script.rpm.sh | sudo bash
  sudo yum makecache -y --disablerepo='*' --enablerepo='rabbitmq_rabbitmq-server'

• selinux policy utils package name is different: policycoreutils-python -> policycoreutils-python-utils
• modify [includes/common.sh](https://github.com/StackStorm/st2-packages/blob/f0e1e650d17ccee9c8e4ab05bfdbd1a664378089/scripts/st2bootstrap-el8.sh#L256-L260) to force PEM key type.
• MongoDB to 4.0 (Readme not updated yet)

See StackStorm/st2docs#955 more differences from EL7 -> EL8.

[amanda11]

ansible reports the default package manager as dnf for Centos 8. As part of this issue would you want to:

1. use dnf install rather than yum install (and therefore create mongodb_dnf.yml etc...) OR
2. continue to use yum install, and therefore detect that if ansible_facts.pkg_mgr is dnf - still use yum?

[arm4b]

@amanda11 Thanks for raising this!

For consistency reasons with st2 installation documentation, scripted installer and less diff in ansible-st2 codebase I'd prefer to rely on older yum when adding EL8 support.

[amanda11]

Are you looking for someone to take this on?

[punkrokk]

@amanda11 Happy to work with you/help you get this done. At the moment we are working on releasing ST2 3.2 which will include beta support for EL8.

FWIW - regarding yum and dnf it's my understanding that dnf is backwards compatible with yum and the yum is an alias to dnf.

Once the EL8 packages are released we can start a list of what needs to be addressed.

[amanda11]

@punkrokk Sounds good. I had a quick play the other-day with ansible and Centos 8, and the first thing it failed on was the fact that it tries looking for files like mongodb_dnf.yml as the ansible facts package mgr reports it as dnf rather than yum (hence the inquiry).

[amanda11]

@punkrokk I have some free time to start looking at this if its worth starting. I was first going to take a look at the one line installer to see the differences it does for EL8.
Currentlly just applying the differences between the el7 and el8 bootstrap scripts to see differences and building into playbooks.

[amanda11]

On a fork I have playbook changes that successfully install on Centos8 from the ansible playbook and pass the smoke tests.
Need to tidy up, and re-test with EWC and Centos 7 (and Ubuntu if known version of Ubuntu the playbooks work on...)

Are the smoke-tests in the ansible-playbook sufficient for checking that its installed correctly or is there more recommended?