conn: add container/podman/docker connection

[pbrezina]

This pull requests introduce a generic connection class so we
are no longer bounded to SSH. It also implements a container
connection so podman or docker can be used instead.

This brings some breaking changes:

• mhc.yaml: ssh configuration was replaced with conn
• host.ssh was replaced with host.conn
• generic classes should be used instead of SSH specific: SSHClient -> Connection, SSHProcess -> Process, SSHProcessResult -> ProcessResult and so on.

Example configuration for SSH:

  - hostname: dc.ad.test
    role: ad
    os:
      family: windows
    conn:
      type: ssh
      username: [email protected]
      password: vagrant
    config:
      adminpw: vagrant
      client:
        ad_domain: ad.test

Example configuration for podman:

  - hostname: master.ipa.test
    role: ipa
    conn:
      type: podman
      name: ipa
      sudo: True
    config:
      client:
        ipa_domain: ipa.test
        krb5_keytab: /enrollment/ipa.test.keytab
        ldap_krb5_keytab: /enrollment/ipa.test.keytab

[pbrezina]

Documentation is not included. After this is merged, I plan to restructuralize and rewrite the documentation so it can contain all the new features we added lately.

[jakub-vavra-cz]

Why not keep the "ssh:" section intact?
It would be better to add an additional configuration item "conn_type:" instead with default value ssh. That can be switched to podman or docker.

[pbrezina]

Why not keep the "ssh:" section intact? It would be better to add an additional configuration item "conn_type:" instead with default value ssh. That can be switched to podman or docker.

I want to keep the amount of reserved keywords minimal. This way, we have reserved only "conn", instead of "conn_type", "ssh", "podman" and "docker".

[justin-stephenson]

Example configuration for podman:

  - hostname: master.ipa.test
    role: ipa
    conn:
      type: podman
      name: ipa
   ...

Why not container instead of name here? When first looking at this it wasn't clear to me what name should be (arbitrary or otherwise)

[pbrezina]

Example configuration for podman:

  - hostname: master.ipa.test
    role: ipa
    conn:
      type: podman
      name: ipa
   ...

Why not container instead of name here? When first looking at this it wasn't clear to me what name should be (arbitrary or otherwise)

Great idea. Thank you. Done.

[justin-stephenson]

Ack, thank you.

[danlavu]

The code looks good! I haven't had a chance to test it yet. Do you want me to approve it, or can I get to it early next week?

[thalman]

Great work, thanks