93e481a247
I think this badge is misleading as we are not a library so the number of projects we are used in is not really relevant to our adoption. It is more-or-less just the number of external plugins people have built.
197 lines
7 KiB
Markdown
197 lines
7 KiB
Markdown
[](https://coredns.io)
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[](https://godoc.org/github.com/coredns/coredns)
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[](https://travis-ci.org/coredns/coredns)
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[](https://codecov.io/github/coredns/coredns?branch=master)
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[](https://goreportcard.com/report/coredns/coredns)
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[](https://app.fossa.io/projects/git%2Bhttps%3A%2F%2Fgithub.com%2Fcoredns%2Fcoredns?ref=badge_shield)
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[](https://bestpractices.coreinfrastructure.org/projects/1250)
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CoreDNS (written in Go) chains [plugins](https://coredns.io/plugins). Each plugin performs a DNS
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function.
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CoreDNS is a [Cloud Native Computing Foundation](https://cncf.io) inception level project.
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CoreDNS is the successor to [SkyDNS](https://github.com/skynetservices/skydns). SkyDNS is a thin
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layer that exposes services in etcd in the DNS. CoreDNS builds on this idea and is a **generic** DNS
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server that can talk to multiple backends (etcd, kubernetes, etc.).
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CoreDNS aims to be a fast and flexible DNS server. The keyword here is *flexible*: with CoreDNS you
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are able to do what you want with your DNS data. And if not: write a plugin!
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CoreDNS can listen for DNS request coming in over UDP/TCP (go'old DNS), TLS ([RFC
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7858](https://tools.ietf.org/html/rfc7858)) and [gRPC](https://grpc.io) (not a standard).
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Currently CoreDNS is able to:
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* Serve zone data from a file; both DNSSEC (NSEC only) and DNS are supported (*file*).
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* Retrieve zone data from primaries, i.e., act as a secondary server (AXFR only) (*secondary*).
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* Sign zone data on-the-fly (*dnssec*).
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* Load balancing of responses (*loadbalance*).
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* Allow for zone transfers, i.e., act as a primary server (*file*).
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* Automatically load zone files from disk (*auto*).
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* Caching (*cache*).
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* Health checking endpoint (*health*).
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* Use etcd as a backend, i.e., a 101.5% replacement for
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[SkyDNS](https://github.com/skynetservices/skydns) (*etcd*).
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* Use k8s (kubernetes) as a backend (*kubernetes*).
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* Serve as a proxy to forward queries to some other (recursive) nameserver (*proxy*).
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* Provide metrics (by using Prometheus) (*metrics*).
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* Provide query (*log*) and error (*error*) logging.
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* Support the CH class: `version.bind` and friends (*chaos*).
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* Profiling support (*pprof*).
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* Rewrite queries (qtype, qclass and qname) (*rewrite*).
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* Echo back the IP address, transport and port number used (*whoami*). This is also the default
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plugin that gets loaded when CoreDNS can't find a Corefile to load.
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Each of the plugins has a README.md of its own, see [coredns.io/plugins](https://coredns.io/plugins)
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for all in-tree plugins, and [coredns.io/explugins](https://coredns.io/explugins) for all
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out-of-tree plugins.
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## Status
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CoreDNS can be used as an authoritative nameserver for your domains. CoreDNS should be able to
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provide you with enough functionality to replace parts of BIND 9, Knot, NSD or PowerDNS and SkyDNS.
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## Compilation
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Check out the project and do dependency resolution with:
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go get github.com/coredns/coredns
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Some of the dependencies require Go version 1.8 or later.
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(If you already have the source of CoreDNS checked out in the appropriate place in your `GOPATH`, you can get all
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dependencies with `go get ./...`.)
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Then use `go build` as you would normally do:
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go build
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This should yield a `coredns` binary.
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## Compilation with Docker
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CoreDNS requires Go to compile. However, if you already have docker installed and prefer not to setup
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a Go environment, you could build coredns easily:
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```
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$ docker run --rm -i -t -v $PWD:/go/src/github.com/coredns/coredns \
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-w /go/src/github.com/coredns/coredns golang:1.9 make
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```
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The above command alone will have `coredns` binary generated.
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## Examples
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When starting CoreDNS without any configuration, it loads the
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[*whoami*](https://coredns.io/plugins/whoami) plugin and starts listening on port 53 (override with
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`-dns.port`), it should show the following:
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~~~ txt
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.:53
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2016/09/18 09:20:50 [INFO] CoreDNS-001
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CoreDNS-001
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~~~
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Any query send to port 53 should return some information; your sending address, port and protocol
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used.
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If you have a Corefile without a port number specified it will, by default, use port 53, but you
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can override the port with the `-dns.port` flag:
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`./coredns -dns.port 1053`, runs the server on port 1053.
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Start a simple proxy, you'll need to be root to start listening on port 53.
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`Corefile` contains:
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~~~ corefile
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.:53 {
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proxy . 8.8.8.8:53
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log
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}
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~~~
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Just start CoreDNS: `./coredns`. Then just query on that port (53). The query should be forwarded to
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8.8.8.8 and the response will be returned. Each query should also show up in the log which is
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printed on standard output.
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Serve the (NSEC) DNSSEC-signed `example.org` on port 1053, with errors and logging sent to standard
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output. Allow zone transfers to everybody, but specifically mention 1 IP address so that CoreDNS can
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send notifies to it.
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~~~ txt
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example.org:1053 {
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file /var/lib/coredns/example.org.signed {
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transfer to *
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transfer to 2001:500:8f::53
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}
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errors
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log
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}
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~~~
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Serve `example.org` on port 1053, but forward everything that does *not* match `example.org` to a recursive
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nameserver *and* rewrite ANY queries to HINFO.
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~~~ txt
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.:1053 {
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rewrite ANY HINFO
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proxy . 8.8.8.8:53
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file /var/lib/coredns/example.org.signed example.org {
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transfer to *
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transfer to 2001:500:8f::53
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}
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errors
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log
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}
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~~~
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IP addresses are also allowed. They are automatically converted to reverse zones:
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~~~ corefile
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10.0.0.0/24 {
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whoami
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}
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~~~
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Means you are authoritative for `0.0.10.in-addr.arpa.`.
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This also works for IPv6 addresses. If for some reason you want to serve a zone named `10.0.0.0/24`
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add the closing dot: `10.0.0.0/24.` as this also stops the conversion.
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This even works for CIDR (See RFC 1518 and 1519) addressing, i.e `10.0.0.0/25`, CoreDNS will then
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check if the `in-addr` request falls in the correct range.
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Listening on TLS and for gRPC? Use:
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~~~ corefile
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tls://example.org grpc://example.org {
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whoami
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}
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~~~
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Specifying ports works in the same way:
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~~~ txt
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grpc://example.org:1443 {
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# ...
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}
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~~~
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When no transport protocol is specified the default `dns://` is assumed.
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## Community
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- Website: <https://coredns.io>
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- Blog: <https://blog.coredns.io>
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- Twitter: [@corednsio](https://twitter.com/corednsio)
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- Github: <https://github.com/coredns/coredns>
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- Mailing list/group: <coredns-discuss@googlegroups.com>
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- Slack: #coredns on <https://slack.cncf.io>
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## Deployment
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Examples for deployment via systemd and other use cases can be found in the
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[deployment repository](https://github.com/coredns/deployment).
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