Doc: Adding initial hardening guide

[timdeluxe]

What this PR does / why we need it:

ingress-nginx is hardened in several places by default, but it can be done even more secure. This hardening guide looks at best practises documents of CIS benchmarks and a cipherli.st fork and checks what needs to be done of if the ingress-nginx default is already sufficient.
Originally it was discussed here: nginxinc/kubernetes-ingress#887 and so i published it in our own repo, since i was recommended to do so in that issue.
However dodevops/k8s-ingress-nginx-hardening#1 gave me the hint, to add it to this community-driven project and hence this PR.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

How Has This Been Tested?

Tested with make live-docs, but table is still to wide. However i don't know a better format, any recommendations?

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (Basically it is an addition to the documentation)
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes. (Obsolete due to no code change)
• All new and existing tests passed. (Obsolete due to no code change)

WIP remark:

I added the flag WIP since there are some points in the hardening guide, where i have no clue (marked with question marks, like "???"). I need help on those points.
Also as already mentioned above, the table format may be improved to something else, but i have no idea what. Any ideas?

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[k8s-ci-robot]

Hi @timdeluxe. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[aledbf]

/ok-to-test

[aledbf]

@timdeluxe please check the CLA bot hint

[timdeluxe]

/check-cla

[timdeluxe]

@timdeluxe please check the CLA bot hint

I comitted with the wrong email adress (my fault). I hope my amend action helped... If not i might need to do another PR?

[timdeluxe]

@timdeluxe please check the CLA bot hint

I comitted with the wrong email adress (my fault). I hope my amend action helped... If not i might need to do another PR?

Hm, looks like i need to redo the whole PR, because my amend action made a new commit and an old one with the wrong email is still included in the PR. Am i correct?

I would work on the given feedbacks here and then push the changes to another PR and close this one here. Would that be the right way @aledbf ?

[aledbf]

@timdeluxe please squash the commits. I think that is enough. Or you can close this PR and create a new one with just one commit. Up to you :)

[timdeluxe]

@timdeluxe please squash the commits. I think that is enough. Or you can close this PR and create a new one with just one commit. Up to you :)

Squashing worked, thanks. Will work on the feedback in the next days...

[aledbf]

@timdeluxe friendly ping

[timdeluxe]

@aledbf Sorry, i was and am on vacation, will continue to work on this on monday.

[timdeluxe]

Please apologize that it took a biiit longer. I now updated all the points you thankfully gave feedback too. That also closes all open lines with question marks.

[aledbf]

/lgtm
/approve

[aledbf]

@timdeluxe thanks!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, timdeluxe

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