bootstrap could automatically enable --use-ssh-agent when SSH_AUTH_SOCK is present

[zzhou1]

Here is the current oneliner:

adm@tw-1:~> sudo -E crm cluster init --use-ssh-agent -ys /dev/disk/by-partlabel/sbd -N $USER@tw-2

It would be naturally consistent with "ssh", "ssh-copy-id", etc. That means as long as SSH_AUTH_SOCK gets detected, --use-ssh-agent is automatically enabled. We can add code to enforce --use-ssh-agent no if really need to use the local ssh key.

adm@tw-1:~> sudo -E crm cluster init -ys /dev/disk/by-partlabel/sbd -N $USER@tw-2

[liangxin1300]

Don't get your point yet.

adm@tw-1:~> sudo -E crm cluster init --use-ssh-agent -ys /dev/disk/by-partlabel/sbd -N $USER@tw-2

Use --use-ssh-agent to tell crmsh we want to enable ssh-agent
If we don't use --use-ssh-agent option, local ssh key will be created and used:

adm@alp-1:~> sudo -E crm cluster init -ys /dev/sda9 -N adm@alp-2
INFO: Loading "default" profile from /etc/crm/profiles.yml
INFO: Loading "knet-default" profile from /etc/crm/profiles.yml
WARNING: $SSH_AUTH_SOCK is detected. As a tip, using the --use-ssh-agent option could avoid generate local root ssh keys on cluster nodes.
INFO: A new ssh keypair is generated for user adm.
INFO: A new ssh keypair is generated for user hacluster.

[liangxin1300]

@nicholasyang2022 What do you think about this?

On master branch:

• Auto enable ssh agent when SSH_AUTH_SOCK is present, no need to use --use-ssh-agent

• We can add code to enforce '--use-ssh-agent no' if really need to use the local ssh key.

I think the behavior between SLE16 and SLE15SP6+ will be different

[nicholasyang2022]

Auto enable ssh agent when SSH_AUTH_SOCK is present

Yeah, I am going to do this, as it is consistent with the behavior of ssh-copy-id.

[nicholasyang2022]

These changes are needed:

• Default to try to use ssh-agent.
• When ssh-agent is not available, do not fail and fallback to use or generate local key files.
• When there are no keys in the ssh-agent, do not fail and fallback to use or generate local key files.