Fix no "data-server" DNS record for VPC router

[aleskxyz]

Description

This PR adds the capability to VPC VR to answer "data-server" DNS queries based on the source IP of the VM.

1. Creates a new record for "data-server" translated to VR IP of newly create subnet in /etc/hosts file
2. Configure dnsmasq to send response of "data-server" query based on source IP of VM

STEPS TO REPRODUCE

1. Create a VPC
2. Add an isolated network with UserData service with VirtualRouter as provider
3. Create a VM in this network
4. Run "nslookup data-server" command from inside of VM
5. Run "cat /etc/hosts" command from inside of VR

EXPECTED RESULTS

Running "nslookup data-server" command returns IP address of router
Running "cat /etc/hosts" command from inside of VR shows "data-server" record and the VR NIC IP

ACTUAL RESULTS

Running "nslookup data-server" command returns "No answer"
The result of running "cat /etc/hosts" command from inside of VR, don't have any record about "data-server"

Fixes: #4865

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)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Apply the patch directly to VPC VR.
Add new subnet to VR, then add a new VM and check the record existance.
Restart VPC and check recreation of records.
Remove all VMs from the subnet and check the record is deleted.

[DaanHoogland]

this can only work if we know for sure that CsHelper.get_hostname() gives an ip address and no hostname, are we?

[aleskxyz]

this can only work if we know for sure that CsHelper.get_hostname() gives an ip address and no hostname, are we?

@DaanHoogland
CsHelper.get_hostname() gives the hostname of virtual router. As you can see in screenshot, 'r-24-VM' is the hostname. So it should return hostname, not IP.

[DaanHoogland]

sorry, never mind, I mis-interpreted the semantics of add_host(). no ip needed in that parameter, a (list of) hosts-name(s) is fine.

[yadvr]

@blueorangutan package

[blueorangutan]

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

[blueorangutan]

Packaging result: ✔️ centos7 ✔️ debian. SL-JID 303

[weizhouapache]

tested ok

[yadvr]

@blueorangutan test

[blueorangutan]

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

[blueorangutan]

Trillian test result (tid-337)
Environment: kvm-centos7 (x2), Advanced Networking with Mgmt server 7
Total time taken: 33043 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr4873-t337-kvm-centos7.zip
Intermittent failure detected: /marvin/tests/smoke/test_vm_life_cycle.py
Smoke tests completed. 82 look OK, 1 have error(s)
Only failed tests results shown below:

Test	Result	Time (s)	Test File
test_01_migrate_VM_and_root_volume	Error	82.59	test_vm_life_cycle.py
test_02_migrate_VM_with_two_data_disks	Error	51.18	test_vm_life_cycle.py