Lightweight pdns-recursor Docker image

Docker image for PowerDNS Recursor 4.1.x. Super lightweight thanks to the Alpine Linux 3.8 base image. Total image size for the current build is 27.2MB

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Getting the image

You can either clone this repo and build the image yourself or pull it from Docker Hub. The :latest tag on Docker Hub is a daily automated build.

# Example command to build an image
sudo docker image build -t pdns-recursor .

# Example command to pull an image
sudo docker image pull m4rcu5/pdns-recursor:latest

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Using the image

Default configuration

The recursor will work out of the box as long as you query it from a private network. To create a container without any additional configuration simply run:

docker container run \
    --detach \
    --hostname resolver.local \
    --name pdns-recursor \
    --mount type=bind,src=/etc/localtime,dst=/etc/localtime,readonly=true \
    m4rcu5/pdns-recursor:latest

Let's assume the container can be reached on 172.17.0.4. You can now query it with dig for example:

dig +tcp @172.17.0.4 google.com

; <<>> DiG 9.10.3-P4-Ubuntu <<>> +tcp google.com @172.17.0.4
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55033
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com.            IN  A

;; ANSWER SECTION:
google.com.     300 IN  A   216.58.211.110

;; Query time: 37 msec
;; SERVER: 172.17.0.4#53(172.17.0.4)
;; WHEN: Thu Aug 31 23:35:44 CEST 2017
;; MSG SIZE  rcvd: 55

Custom configuration

It is possible to overwrite default settings by defining them in custom .conf files in /data/recursor-conf.d/. As an example this repo contains a zone file for the localhost zone and a configuration file to tell the recursor it has authority for that zone. Let's assume this repo has been cloned to /opt of the container host resulting in something similar to this:

/opt
└── pdns-recursor
    └── data
        ├── recursor-conf.d
        │   └── auth-zones.conf
        ├── scripts
        └── zones
            └── localhost

Now this local folder can be mounted as a volume inside the container:

docker container run \
    --detach \
    --hostname resolver.local \
    --name pdns-recursor \
    --mount type=bind,src=/etc/localtime,dst=/etc/localtime,readonly=true \
    --mount type=bind,src=/opt/pdns-recursor/data,dst=/data,readonly=true \
    m4rcu5/pdns-recursor:latest

Now the recursor will look in /data/zones/localhost whenever it receives a query for that zone.

Let's say we also want the recursor to validate DNSSEC queries. This can be accomplished by creating a .conf file for it and restarting the container:

# Create the config file
echo 'dnssec=validate' > /opt/pdns-recursor/data/recursor-conf.d/dnssec.conf

# Restart the container
docker container restart pdns-recursor

A complete list of settings for the recursor can be found on https://doc.powerdns.com/md/recursor/settings/