Update BIND nameserver zone with Docker hosts via DNS Updates.
Project description
Update BIND nameserver zone with Docker hosts via DNS Updates.
Usage
Docker HostDNS can be run by docker-hostdns wrapper script or directly with python -m docker_hostdns.
usage: docker-entrypoint [-h] [--zone ZONE] [--dns-server DNS_SERVER]
[--dns-key-secret DNS_KEY_SECRET]
[--dns-key-name DNS_KEY_NAME]
[--dns-key-alg {...}]
[--name NAME] [--network NETWORK] [--verbose]
[--syslog [SYSLOG]] [--clear-on-exit]
Update BIND nameserver zone with Docker hosts via DNS Updates.
optional arguments:
-h, --help show this help message and exit
--zone ZONE dns zone to update, defaults to "docker"
--dns-server DNS_SERVER
address of DNS server which will be updated, defaults
to 127.0.0.1
--dns-key-secret DNS_KEY_SECRET
DNS Server key secret for use when updating zone, use
'-' to read from stdin
--dns-key-name DNS_KEY_NAME
DNS Server key name for use when updating zone
--dns-key-alg {...}
DNS Server key algorithm for use when updating zone
--name NAME name to differentiate between multiple instances
inside same dns zone, defaults to current hostname
--network NETWORK network to fetch container names from, defaults to
docker default bridge, can be used multiple times
--verbose, -v give more output - option is additive, and can be used
up to 3 times
--syslog [SYSLOG] enable logging to syslog, defaults to "/dev/log", you
can provide path to unix socket or uri:
<tcp|udp|unix>://<path_or_host>[:<port>]
--clear-on-exit clear zone on exit
The --daemonize options is only available when you have installed python-daemon3 package.
Example named.conf zone configuration with key auth:
include "/etc/bind/docker.key";
zone "docker" in {
type master;
file "/var/bind/dyn/docker.zone";
allow-update {
key "docker-key";
};
};
docker.key can be generated by:
rndc-confgen -a -c docker.key -k docker-key
And then:
echo 'my base64 key secret' | docker-hostdns --dns-key-name docker-key --dns-key-secret -
Host names
Host name is created by using container name and slugifying & trimming it. So /example2::docker will result with example2-docker. In case of name duplication a “-<number>” will be appended, resulting with eg. example2-docker-1
Following dns records are created for each container, given example hostname and docker zone:
IPv4: example.docker
IPv4: *.example.docker
IPv6: example.docker
IPv6: *.example.docker
TXT: _container_<name>.docker with container name as value and instance name as <name>
TXT record is used for keeping track of added hosts so when app is stopped or resumed it keeps its state.
Custom host names
You can set custom host name by using container label pl.glorpen.hostname, its content will be used as container name.
Docker Image
Docker image is available at glorpen/hostdns. For help try docker run --rm -it glorpen/hostdns:latest --help.
Remember to mount /run/docker.sock inside container.
Build image from GitHub
git clone <repo>
cd docker-hostdns/
docker build -t "<image name>" .
Docker environment variables
DNS_SERVER: address of DNS server which will be updated, defaults to 127.0.0.1
DNS_ZONE: DNS zone to update, defaults to docker
DNS_KEY_NAME: DNS Server key name for use when updating zone
DNS_KEY_SECRET: DNS Server key secret for use when updating zone
DNS_KEY_SECRET_FILE: path of file with secret as its content
NAME: name to differentiate between multiple instances inside same dns zone, defaults to current hostname
NETWORK: network to fetch container names from, defaults to docker default bridge, accepts multiple networks as comma delimited list (e.g. network1,network2,network3,..)
VERBOSITY: give more output, accepts 0 to 3, defaults to 0 (equivalent to -v, -vv, -vvv arguments on the command line)
SYSLOG: enable logging to syslog, if set true or yes defaults to “/dev/log”, or you can provide path to unix socket or uri: <tcp|udp|unix>://<path_or_host>[:<port>]
CLEAR_ON_EXIT: clear zone on exit, defaults to false (accepts true or yes)
Securing DNS secret key
To secure secret key (the dns-key-secret option) you can:
passing its contents to env var DNS_KEY_SECRET
setting env var DNS_KEY_SECRET_FILE to path of file with secret as its content
Option --dns-key-secret - will be then automatically prepended and secret key piped to docker-hostdns process.
Working with docker-compose
When using docker-compose for development you can create custom docker network and use it as domain names source.
To do this, create docker network with docker network create example-dns and then run Docker HostDNS with --network example-dns argument.
Next, with example docker-compose.yml:
version: '2.2'
services:
app:
image: example
labels:
pl.glorpen.hostname: example
networks:
default: ~
dns: ~
networks:
dns:
external: true
name: example-dns
you can start container that would be accessible by host as example.docker domain.
2.4.0
added dns server name resolving
added key algorithm parameter for update request signing
2.3.0
configure travis
slim docker image
fixed and added more tests
added more environment variables
2.2.0
added environment variables for docker image
2.1.0
fixed docker entrypoint exit signal handling
added clean-on-exit option to clear used dns zone
2.0.0
added Docker image
watched network interfaces can be now specified by user
container name deduplication now only drops duplicate names
single container can have multiple aliases
short id and other container aliases are now available as dns names
1.1.1
1.1.0
possible breaking change: changed dnspython3 package to just dnspython as Py3 is now supported
1.0.4
host names are now allowed to have dots in them
1.0.3
added tests
added proper domain names coversion
added a way to keep track of hosts when adding & removing containers
1.0.2
fixed error when handling disconnection event without earlier connect one
added app exception logging
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