Handle existing zone in dynamically addition of DNS records

[balajiv113]

In #217 i assumed that we are iterating through all zones until we find a record match but that was wrong. If the zone name matches we are returning error if record is not found.

This PR is about handling existing zones to keep the records array in sync.

[cfergeau]

The addition might need to be added slightly differently, see my comments in the PR.

[cfergeau]

Not so sure it's a good thing to reorder the zones list. Let's say the initial state is:

DNS: []types.Zone{
	{
		Name:      "crc.testing.",
		DefaultIP: net.ParseIP("192.168.127.2"),
	},
	{
		Name: "testing.",
		Records: []types.Record{
			{
				Name: "host",
				IP:   net.ParseIP("192.168.127.3"),
			},
		},
	},
},

And I then want to add gateway.testing:

types.Zone{
	{
		Name: "testing.",
		Records: []types.Record{
			{
				Name: "gateway",
				IP:   net.ParseIP("192.168.127.1"),
			},

	},

After updating the existing zone, testing. will come before crc.testing., and *.crc.testing will return "not found" instead of resolving to 192.168.127.2

[balajiv113]

Ah makes sense thanks for the input i missed out this usecase completely :( I will update the PR to maintain the order of zones as well.

Basically,

• We will insert new zones at last (as we are already handling existing zones case)
• For existing zones keep the location same. (Just append Records to existing one and set DefaultIP)

[balajiv113]

@cfergeau
Addressed the use cases that you have mentioned. Also wrote some new unit test for verifying the addZone cases. Let me know if it looks good now.

Happy to update if any changes are required :)

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: balajiv113, cfergeau

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [cfergeau]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment