CODEWITHSUNDEEP
consul
Erik
Erik

Reputation: 7731

Linking DNS to a consul node

I'm trying to set up a consul agent using an example in "Using Docker" (chapter 11). The example suggests running this to set up one of the consul nodes:

docker run -d --name consul -h consul-1 \
         -p 8300:8300 -p 8301:8301 -p 8301:8301/udp \
         -p 8302:8302/udp -p 8400:8400 -p 8500:8500 \
         -p 172.17.42.1:53:8600/udp \
         gliderlabs/consul agent -data-dir /data -server \
                    -client 0.0.0.0 \
                    -advertise $HOSTA -bootstrap-expect 2

I assume the line with -p 172.17.42.1:53:8600/upp is linking the container's DNS service with the consul node using an IP address that worked for the author. What IP address should I use here?

Upvotes: 0

Views: 226

Answers (2)

Jagatveer Singh
Jagatveer Singh

Reputation: 195

You seem to be running an example setup, so better if you expose it to your localhost 127.0.0.1 instead. That's a DNS service, as long as you give a dig command using the correct port for DNS, it will just work. For example following will do for port 8600:

dig @127.0.0.1 -p 8600 stackoverflow.service.consul

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.62.rc1.55.amzn1 <<>> @127.0.0.1 -p 53 tracker.service.consul
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57167
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;stackoverflow.service.consul.      IN  A

;; ANSWER SECTION:
stackoverflow.service.consul.   0   IN  A   10.X.X.X

;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Jul  7 11:29:01 2017
;; MSG SIZE  rcvd: 56

If you want it to work on the default DNS port so that the queries can directly be handled. You can use something like dnsmaq or any of the methods listed at the following link for DNS forwarding:

https://www.consul.io/docs/guides/forwarding.html

Upvotes: 0

Erik
Erik

Reputation: 7731

Looks like 172.17.42.1 was the default bridge address for docker 1.8 to use when a container is connecting to the host. This changed in 1.9 and seems to be 172.17.0.1 for me -- although I don't know if this is a guaranteed.

Upvotes: 1

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