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* readme: add text on backward incompat changes Document the process of releasing backwards incompatible changes. Signed-off-by: Miek Gieben <miek@miek.nl> * slightly better Signed-off-by: Miek Gieben <miek@miek.nl> * Add an example Signed-off-by: Miek Gieben <miek@miek.nl> * Be more explicit in naming the segments increased Signed-off-by: Miek Gieben <miek@miek.nl>
223 lines
7.8 KiB
Markdown
223 lines
7.8 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://hub.docker.com/r/coredns/coredns)
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[](https://goreportcard.com/report/coredns/coredns)
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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) graduated project.
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CoreDNS is 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 by utilizing plugins. If some functionality is not
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provided out of the box you can add it by [writing a plugin](https://coredns.io/explugins).
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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* and *auto*).
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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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* Use etcd as a backend (replace [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 (*forward*).
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* Provide metrics (by using Prometheus) (*metrics*).
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* Provide query (*log*) and error (*errors*) logging.
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* Support the CH class: `version.bind` and friends (*chaos*).
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* Support the RFC 5001 DNS name server identifier (NSID) option (*nsid*).
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* Profiling support (*pprof*).
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* Rewrite queries (qtype, qclass and qname) (*rewrite* and *template*).
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And more. Each of the plugins is documented. 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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## Compilation from Source
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Check out the project:
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~~~
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% git clone https://github.com/coredns/coredns
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~~~
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We vendor most (not all!) packages. This is mostly because vendoring isn't a perfect solution (in
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Go). We don't vendor `mholt/caddy` and `miekg/dns` for instance. Using `make` will pull down these
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dependencies and checks out the correct version as well.
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Next just run `make`:
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~~~
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% make
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~~~
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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:1.11 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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forward . 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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forward . 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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We're most active on Github (and Slack):
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- Github: <https://github.com/coredns/coredns>
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- Slack: #coredns on <https://slack.cncf.io>
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More resources can be found:
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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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- Mailing list/group: <coredns-discuss@googlegroups.com> (not very active)
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## Deployment
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Examples for deployment via systemd and other use cases can be found in the [deployment
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repository](https://github.com/coredns/deployment).
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## Deprecation Policy
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When there is a backwards incompatible change in CoreDNS the following process is followed:
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* Release x.y.z: Announce that in the next release we will make backward incompatible changes.
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* Release x.y+1.0: Increase the minor version and set the patch version to 0. Make the changes,
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but allow the old configuration to be parsed. I.e. CoreDNS will start from an unchanged
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Corefile.
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* Release x.y+1.1: Increase the patch version to 1. Remove the lenient parsing, so CoreDNS will
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not start if those features are still used.
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E.g. 1.3.1 announce a change. 1.4.0 a new release with the change but backward compatible config.
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And finally 1.4.1 that removes the config workarounds.
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## Security
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### Security Audit
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A third party security audit was performed by Cure53, you can see the full report [here](https://coredns.io/assets/DNS-01-report.pdf).
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### Reporting security vulnerabilities
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If you find a security vulnerability or any security related issues, please DO NOT file a public
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issue, instead send your report privately to `security@coredns.io`. Security reports are greatly
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appreciated and we will publicly thank you for it.
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Please consult [security vulnerability disclosures and security fix and release process document](https://github.com/coredns/coredns/SECURITY-RELEASE-PROCESS.md)
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