riftbit/coredns repository overview

⁠CoreDNS

Docker container⁠ for github.com/coredns/coredns⁠ (with additional plugins)

This Docker image is basically scratch + CoreDNS + TLS certificates (for DoT, DoH, and gRPC).

Actual Version: 1.8.7

Documentation could be found here⁠

⁠Supported platforms

This container build with CoreDNS is a DNS server with many plugins and supports multiple platforms

• linux/amd64
• linux/arm64
• linux/arm/v7
• linux/arm/v6
• linux/mips64le
• linux/mipsle
• linux/mips64
• linux/mips
• linux/ppc64le
• linux/s390x
• linux/riscv64

⁠Plugins list

Plugins updated or created by riftbit

• docker:github.com/rb-coredns/coredns-dockerdiscovery⁠
• pdsql:github.com/rb-coredns/coredns-pdsql⁠ - in progress
• ipin:github.com/rb-coredns/coredns-ipin⁠ - in progress

Community version plugins

• git:github.com/miekg/coredns-git⁠
• records:github.com/coredns/records⁠
• mdns:github.com/openshift/coredns-mdns⁠
• alias:github.com/serverwentdown/alias⁠
• fanout:github.com/networkservicemesh/fanout⁠
• dump:github.com/miekg/dump⁠
• pdsql_mysql:github.com/jinzhu/gorm/dialects/mysql⁠
• pdsql_sqlite:github.com/jinzhu/gorm/dialects/sqlite⁠
• pdsql_postgres:github.com/jinzhu/gorm/dialects/postgres⁠
• pdsql_mssql:github.com/jinzhu/gorm/dialects/mssql⁠

⁠ToDo Plugins list

This plugins are outdated and not works. They will be forked and updated in github.com/rb-coredns⁠

• unbound:github.com/coredns/unbound⁠
• redisc:github.com/miekg/redis⁠
• redis:github.com/hawell/redis⁠

⁠Overview

CoreDNS is a DNS server. It is written in Go.

CoreDNS is different from other DNS servers, such as (all excellent) BIND⁠, Knot⁠, PowerDNS⁠ and Unbound⁠ (technically a resolver, but still worth a mention), because it is very flexible, and almost all functionality is outsourced into plugins.

Plugins can be stand-alone or work together to perform a “DNS function”.

So what’s a “DNS function”? For the purpose of CoreDNS, we define it as a piece of software that implements the CoreDNS Plugin API. The functionality implemented can wildly deviate. There are plugins that don’t themselves create a response, such as metrics⁠ or cache⁠, but that add functionality. Then there are plugins that do generate a response. These can also do anything: There are plugins that communicate with Kubernetes⁠ to provide service discovery, plugins that read data from a file⁠ or a database.

There are currently about 30 plugins included in the default CoreDNS install, but there are also a whole bunch of external plugins that you can compile into CoreDNS to extend its functionality.

> CoreDNS is powered by plugins.

Writing new plugins⁠ should be easy enough, but requires knowing Go and having some insight into how DNS works. CoreDNS abstracts away a lot of DNS details, so that you can just focus on writing the plugin functionality you need.

⁠Example run

This container search Corefile in /coredns-conf/Corefile by default. You can mount this directory and change some configs.

Create volume for data and configs

docker volume create coredns-conf

Put your Corefile to this volume

example Corefile:

. {
    health
    ready

    hosts
    
    nsid Use The Force

    forward . 8.8.8.8:53 8.8.4.4 
    
    prometheus
    errors
    log
    whoami
    cache
}

.:5353 {
    forward . tls://1.1.1.1 tls://1.0.0.1 {
       tls_servername cloudflare-dns.com
       health_check 5s
    }
    
    prometheus
    errors
    log
    whoami
    cache
}

.:25353 {
    forward . tls://9.9.9.9 {
        health_check 5s
        except example.org
    }
    prometheus
    errors
    log
    whoami
    cache
}


example.com:53 {
    file /coredns-conf/example.dns.db
    prometheus
    errors
    log
    whoami
}

.:15353 {
    docker unix:///var/run/docker.sock {
        domain docker.loc
        hostname_domain docker-host.loc
    }
    prometheus
    errors
    log
    whoami
}

And run container

docker run -d \
  --hostname coredns \
  --name coredns \
  --net host \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v coredns-conf:/coredns-conf \
  --restart unless-stopped \
riftbit/coredns

For docker network usage create new network:

docker network inspect coredns-network >/dev/null 2>&1 || \
    docker network create --driver bridge --subnet=172.153.0.0/16 coredns-network

And run docker container in coredns-network

docker run -d \
  --hostname coredns \
  --name coredns \
  --net coredns-network \
  --ip 172.153.0.53 \
  -p 127.0.0.153:53:53/udp \
  -p 127.0.0.153:53:53/tcp \
  -p 9153:9153 \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v coredns-conf:/coredns-conf \
  --restart unless-stopped \
riftbit/coredns

Port 9153 used for Prometheus by default.

Updated at 2022-02-06T23:35:04Z