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jamgocoop/docker-dns

By jamgocoop

•Updated about 1 month ago

Automatic container DNS for Docker in a single Python file.

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jamgocoop/docker-dns repository overview

⁠docker-dns

Automatic container DNS for Docker⁠ in a single Python file.

Note that docker-dns-rest⁠ expands on this, adding a REST API to add and remove domain names dynamically, allowing multiple domain names to be associated with containers, either by name or container ID. It also includes support for wildcards.

⁠Usage

Run some containers:

% docker run -d --name foo ubuntu bash -c "sleep 600"

Start up dockerdns:

% docker run --name dns -v /var/run/docker.sock:/docker.sock jamgocoop/docker-dns \
    --domain example.com

Start more containers:

% docker run -d --name bar ubuntu bash -c "sleep 600"

Check dockerdns logs:

% docker logs dns
2014-10-08T20:45:37.349161 [dockerdns] table.add dns.example.com -> 172.17.0.3
2014-10-08T20:45:37.351574 [dockerdns] table.add foo.example.com -> 172.17.0.2
2014-10-08T20:45:37.351574 [dockerdns] table.add bar.example.com -> 172.17.0.4

Start up dockerdns with multiple domains:

% docker run --name dns -v /var/run/docker.sock:/docker.sock jamgocoop/docker-dns \
    --domain example.com alias.com

Check dockerdns logs:

% docker logs dns
2014-10-08T20:45:37.349161 [dockerdns] table.add dns.example.com -> 172.17.0.3
2014-10-08T20:45:37.349161 [dockerdns] table.add dns.alias.com -> 172.17.0.3
2014-10-08T20:45:37.351574 [dockerdns] table.add foo.example.com -> 172.17.0.2
2014-10-08T20:45:37.351574 [dockerdns] table.add foo.alias.com -> 172.17.0.2
2014-10-08T20:45:37.351574 [dockerdns] table.add bar.example.com -> 172.17.0.4
2014-10-08T20:45:37.351574 [dockerdns] table.add bar.alias.com -> 172.17.0.4

Query for the containers by hostname:

% host foo.example.com 172.17.0.3
Using domain server:
Name: 172.17.0.3
Address: 172.17.0.3#53
Aliases:

foo.example.com has address 172.17.0.2
foo.example.com has address 172.17.0.2

Use dns container as a resolver inside a container:

% docker run -it --dns $(docker inspect -f '{{.NetworkSettings.IPAddress}}' dns) \
    --dns-search example.com ubuntu bash

root@95840788bf08:/# cat /etc/resolv.conf
nameserver 172.17.0.3
search example.com

root@95840788bf08:/# ping foo
PING foo.example.com (172.17.0.2) 56(84) bytes of data.
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.112 ms
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.112 ms

Names not rooted in example.com will be resolved recursively using Google's resolver 8.8.8.8 by default:

root@95840788bf08:/# ping github.com
PING github.com (192.30.252.128) 56(84) bytes of data.
64 bytes from 192.30.252.128: icmp_seq=1 ttl=61 time=21.3 ms

To disable recursive resolution, use the --no-recursion flag:

% docker run --name dns -v /var/run/docker.sock:/docker.sock jamgocoop/docker-dns \
    --domain example.com --no-recursion

Now names not rooted in example.com will fail to resolve:

% docker run -it --dns $(docker inspect -f '{{.NetworkSettings.IPAddress}}' dns) \
    --dns-search example.com ubuntu bash
root@4d15342387b0:/# ping github.com
ping: unknown host github.com

To add static host name, use the --record option:

% docker run --name dns -v /var/run/docker.sock:/docker.sock jamgocoop/docker-dns \
    --domain example.com --record test:172.17.0.100

$ nslookup test.example.com 172.17.0.3 (dns container ip)
Server:		172.17.0.3
Address:	172.17.0.3#53

Name:	test.example.com
Address: 172.17.0.100

To add external static host name, use the --record-external option:

% docker run --name dns -v /var/run/docker.sock:/docker.sock jamgocoop/docker-dns \
    --domain example.com --record-external www.montoto.org:10.0.0.5

$ nslookup www.montoto.org 172.17.0.3 (dns container ip)
Server:		172.17.0.3
Address:	172.17.0.3#53

Name:	www.montoto.org
Address: 10.0.0.5

$ nslookup www.montoto.org 8.8.8.8
Server:		8.8.8.8
Address:	8.8.8.8#53

Non-authoritative answer:
Name:	www.montoto.org
Address: 212.89.28.201

To add custom alias for a container, include label org.jamgo.dns.alias:

% docker run -d --name foo --label org.jamgo.dns.alias=baz.otherdomain.org ubuntu bash -c "sleep 600"

$ nslookup foo.example.com 172.17.0.3 (dns container ip)
Server:		172.17.0.3
Address:	172.17.0.3#53

Name:	foo.example.com
Address: 10.0.0.5

$ nslookup baz.otherdomain.org 172.17.0.3 (dns container ip)
Server:		172.17.0.3
Address:	172.17.0.3#53

Name:	baz.otherdomain.org
Address: 10.0.0.5

⁠License

Copyright (c) 2014 Patrick Hensley

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Tag summary

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Image

Digest

sha256:5bcf7e75e…

Size

20.4 MB

Last updated

about 7 years ago

docker pull jamgocoop/docker-dns