Add check to resolve host with specified nameserver

[soellman]

The use case here is to check and see if the nameserver is resolving what we'd expect instead of whether a name can be resolved on the host.

[langston-barrett]

This looks easy to do. I'm planning to implement this using a dns library, rather than a call to nslookup or some such. An example application that does exactly what this check needs is available here.

[soellman]

Awesome. I'd be happy do this to too if you like.

[langston-barrett]

@soellman Already working on it :) I could use a little help on the template functions, as I'm less sure where to start with those. I'll push my branch on this once I have an intial setup, and maybe you could do the same with templating functions, if you have the time?

[soellman]

Sure, no problem. I'll work on it tomorrow.
-o

[langston-barrett]

@soellman This check is now in the branch check/dns-arecord. It currently only supports A records. I'll let you give it a whirl before merging, in case it doesn't fit your use case or doesn't work as you might expect.

"aRecord"

• Description: Test whether or not the DNS server resolves the given name to the expected IP address
• Inputs:
  • Name, e.g. "mozilla.org"
  • Expected IP address, e.g. "192.168.0.1"
  • DNS server to check with, e.g. "8.8.8.8"

[soellman]

I'd vote for splitting this up a bit. Maybe instead of aRecord, you could have:

resolveDNS which takes name, nameserver (optional?), type (default A?) - like the "host" check but with args
resolveDNSMatches which takes name, value, nameserver (optional?), type (default A?)

For my case, I don't actually want to know what the result was, just that I got one. This might be used for testing a forwarding dns server with a well known name (like google.com).

And to make it simple for now, most people will only use the A record anyways so support for more record types could get filled out if/when people request them.

I tested the branch and the simple matching case works great :)
-o