tools/write-ssh-key-fingerprints: do not display empty header/footer

[dermotbradley]

When console output of SSH info is disabled show no headers/footers.

Prevent risk of message text being interpreted as "logger" option by
appending "--" to logger options.

Correct syslog output that was tagged with "ec2" regardless of DataSource
in use. Now use "cloud-init" tag instead.

Various "shellcheck" corrections.

Add testcase for disabled output of SSH host keys.

LP: #1915460

Provides alternative solution to #811.

Test Steps

In user-data config add either, or both, of the following lines:

ssh_fp_console_blacklist: [ 'ssh-dsa', 'ssh-dss', 'ssh-rsa', 'ssh-ed25519' ]
ssh_key_console_blacklist: [ 'ssh-dsa', 'ssh-dss', 'ssh-rsa', 'ssh-ed25519' ]

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Overall, this change looks good. Might be worth making a function out of the shellcheck comment and the logger options to cleanup the calls to logger.

I appreciate the additional cloud tests, but unfortunately these tests are deprecated now. Docs for the new test framework are here, but the TLDR for this PR would be to add a test to test_keys_to_console.py with a full blacklist in the cloud-config and assert there's no headers/footers (similar to the bottom two tests in the file)

[dermotbradley]

@TheRealFalcon Hi there

I'll find some time in the next few days to work on this.

Regarding the correction of the 'ec2' string - @OddBloke mentioned on IRC that there might be some stuff out there (Subquity?) relying on that value and he would look into it further. I can drop this portion of the PR if its likely to cause problems.

[github-actions]

Hello! Thank you for this proposed change to cloud-init. This pull request is now marked as stale as it has not seen any activity in 14 days. If no activity occurs within the next 7 days, this pull request will automatically close.

If you are waiting for code review and you are seeing this message, apologies! Please reply, tagging mitechie, and he will ensure that someone takes a look soon.

(If the pull request is closed and you would like to continue working on it, please do tag mitechie to reopen it.)

[dermotbradley]

Overall, this change looks good. Might be worth making a function out of the shellcheck comment and the logger options to cleanup the calls to logger.

Done.

the TLDR for this PR would be to add a test to test_keys_to_console.py with a full blacklist in the cloud-config and assert there's no headers/footers (similar to the bottom two tests in the file)

Done.

[dermotbradley]

@mitechie ping!

[mitechie]

pong! I've cleared the tag and we'll get another round of reviews going. Thanks for the ping.

[TheRealFalcon]

Looking good. Just a couple changes the integration test needed

[TheRealFalcon]

Thanks!