Quick DNS note

#1

Kurt wore me down, and you should now be able to use _local_ip.internal to get your local IP address, in addition to /etc/hosts or ip a or whatever.

4 Likes
#2

This simplifies things sooo much. Thank you @thomas and @kurt :blue_heart:

1 Like
#3

I FIND THIS BAFFLING BUT OK.

:slight_smile:

2 Likes
#4

I don’t really understand how you fetch the IP address?
Let’s take an example, I’ve myapp as an application name.

So for fetching the local IP I’ve to do a DNS lookup on _local_ip.myapp.internal?
I tried but it didn’t work.

#5

It’d be _local_ip.internal

1 Like
#6

I found the correct DNS server, it’s fdaa::3.

Previous message:

Summary

From the fly VM that I need to do that DNS request?

It doesn’t seem like it’s returning something:

/ # dig AAAA _local_ip.internal

; <<>> DiG 9.16.6 <<>> AAAA _local_ip.internal
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 5054
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;_local_ip.internal.		IN	AAAA

;; AUTHORITY SECTION:
.			86357	IN	SOA	a.root-servers.net. nstld.verisign-grs.com. 2021021301 1800 900 604800 86400

;; Query time: 4 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Sat Feb 13 20:48:46 UTC 2021
;; MSG SIZE  rcvd: 122

EDIT: I tried with the DNS server specified in the docs but no success:

/ # dig @fdaa:0:33::3 AAAA _local_ip.internal +tcp
;; Connection to fdaa:0:33::3#53(fdaa:0:33::3) for _local_ip.internal failed: timed out.
;; Connection to fdaa:0:33::3#53(fdaa:0:33::3) for _local_ip.internal failed: timed out.

; <<>> DiG 9.16.6 <<>> @fdaa:0:33::3 AAAA _local_ip.internal +tcp
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached

;; Connection to fdaa:0:33::3#53(fdaa:0:33::3) for _local_ip.internal failed: timed out.
/ # dig @fdaa:0:33::3 AAAA _local_ip.internal

; <<>> DiG 9.16.6 <<>> @fdaa:0:33::3 AAAA _local_ip.internal
; (1 server found)
;; global options: +cmd
;; connection timed out; no servers could be reached
#7

Yeah, it looked like before you were trying to do the lookup over a WireGuard gateway, to the DNS server we give WireGuard connections. _local_ip only gives the addresses for Fly app instances. It is a weird special name, and I added it begrudgingly. :slight_smile:

Let me say this right now: we do the minimal DNS required to make private networking work, but we’re not committed to ungainly minimalism, and if there’s DNS stuff y’all would like us to do, just ask.