openssh_cert: Make it possible to use a signing key stored in ssh-agent

[dougstanley]

SUMMARY

If the ssh signing key is password protected, and the user has it unlocked in an ssh-agent, an additional flag needs to be passed to ssh-keygen in order for it to use the key from the agent when signing. I propose an additional optional module boolean argument to add the flag needed.

ISSUE TYPE

• Feature Idea

COMPONENT NAME

openssh_cert.py

ADDITIONAL INFORMATION

See summary.

- openssh_cert:
    type: user
    signing_key: /path/to/private_key
    use_agent: yes
    public_key: /path/to/public_key.pub
    path: /path/to/certificate
    valid_from: always
    valid_to: forever