cloud-init: Add support for certmonger

This bug was originally filed in Launchpad as [LP: #1865352](https://bugs.launchpad.net/cloud-init/+bug/1865352)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2020-03-01T15:47:50.893892+00:00

date_fix_committed = None

date_fix_released = None

id = 1865352

importance = undecided

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1865352

milestone = None

owner = minfrin

owner_name = Graham Leggett

private = False

status = triaged

submitter = minfrin

submitter_name = Graham Leggett

tags = []

duplicates = []

_Launchpad user **Graham Leggett(minfrin)** wrote on 2020-03-01T15:47:50.893892+00:00_

This is a request to integrate certmonger with cloud-init, such that certificates can be requested and provisioned as part of the initialisation process.

Possible sample configuration:

certs:
Redwax Interop:
type: scep
url: http://interop.redwax.eu/test/simple/scep
requests:
- certificate: /etc/pki/interop/test.example.com.cert
key: /etc/pki/interop/test.example.com.key
key-type: rsa
key-bits: 4096

and so on, corresponding to the following commands:

getcert add-scep-ca -c "Redwax Interop" -u http://interop.redwax.eu/test/simple/scep
getcert request -f /etc/pki/interop/test.example.com.cert -k /etc/pki/interop/test.example.com.key -c "Redwax Interop" -I test.example.com -D test.example.com -G rsa -g 4096 -u digitalSignature -u keyEncipherment -L challenge