Preventing port 53 being added as lb rule when dns service is availab…

[Spaceman1984]

…le in network offering

Description

Throwing an error when port 53 is added to a load balancer when DNS is available on the network service offering.

Fixes: #4285

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

Screenshots (if appropriate):

How Has This Been Tested?

Try to add port 53 as a public port as a load balancer rule, an error will be returned.

[Spaceman1984]

@blueorangutan package

[blueorangutan]

@Spaceman1984 a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result: ✔centos7 ✖centos8 ✔debian. JID-2333

[Spaceman1984]

@blueorangutan test

[blueorangutan]

@Spaceman1984 a Trillian-Jenkins test job (centos7 mgmt + kvm-centos7) has been kicked to run smoke tests

[weizhouapache]

code lgtm

[blueorangutan]

Trillian test result (tid-3128)
Environment: kvm-centos7 (x2), Advanced Networking with Mgmt server 7
Total time taken: 30101 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr4442-t3128-kvm-centos7.zip
Smoke tests completed. 83 look OK, 0 have error(s)
Only failed tests results shown below:

Test	Result	Time (s)	Test File

[DaanHoogland]

code looks good. looks more complicated than it is due to the redundant result == null check being removed. good cleanup