add the ability to use custom domains

[miketweaver]

With this change, it provides the user the optional ability to use custom DNS overrides. This is useful for providing domain names to local caching services.

How do you use this?

1. Create your container with a special bind mount. I my case I used: -v $(pwd)/custom.db:/etc/bind/cache/custom.db

2. Create your override file. In my case it looked like this:

   notes.hackerlan.party           A       10.42.0.230
   games.hackerlan.party           A       10.42.0.230
   file-server.hackerlan.party     A       10.42.0.231
   dns.hackerlan.party             A       10.42.0.232
   cache.hackerlan.party           A       10.42.0.233
   quake.hackerlan.party           A       10.42.0.250

That's it.

Evidence it works:

$ dig @10.42.0.232 quake.hackerlan.party

; <<>> DiG 9.11.3-1ubuntu1.9-Ubuntu <<>> @10.42.0.232 quake.hackerlan.party
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39338
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: bb3f67a5def99fdc6b59e4965dd8dffe77db4ce618fb5ab9 (good)
;; QUESTION SECTION:
;quake.hackerlan.party.         IN      A

;; ANSWER SECTION:
quake.hackerlan.party.  5       IN      A       10.42.0.250

;; AUTHORITY SECTION:
rpz.                    60      IN      NS      localhost.

;; Query time: 4 msec
;; SERVER: 10.42.0.232#53(10.42.0.232)
;; WHEN: Sat Nov 23 00:30:05 MST 2019
;; MSG SIZE  rcvd: 120

Note: this is optional. If you do nothing different, it should continue to work as it did before. The $INCULDE will include a file that does not exist, as such your zone file will be unchanged.

[VibroAxe]

I like the feature, but this could probably do with some documentation. Could you add a section to the end of the README file explaining how to use and we'll accept the PR

[miketweaver]

@VibroAxe Ok. That documentation has been added.

[miketweaver]

@VibroAxe Let me know if there is anything else you would like me to add to this.

[miketweaver]

After some more research, I see that you have moved the documentation for the container to your website.

I've moved my documentation to there: https://github.com/lancachenet/lancachenet.github.io/pull/23

[miketweaver]

I just went and re-verifed that this works, even 8 months later.

Any chance of accepting this?

[VibroAxe]

@miketweaver apologies, I'm not sure how this got left by the way side. It looks good thanks for the PR and effort getting this one in