96 lines
6 KiB
Text
96 lines
6 KiB
Text
== CoreDNS Proposal
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*Name of project:* CoreDNS
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*Description*
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CoreDNS is a fast, flexible DNS server that is designed to be performant with a flexible implementation. This flexibility allows CoreDNS to be easily extended to support various data sources and to implement rich DNS service behaviors: for example, response caching, query rewrite, load-balancing, zone transfer and signing.
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CoreDNS is the successor of SkyDNS. SkyDNS is a DNS server that has etcd as the datastore backend. It is widely
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used in cloud deployments, but lacks the flexibility we envision for CoreDNS.
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*Sponsor / Advisor from TOC*: Jonathan Boulle
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*Unique Identifier*: coredns
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*License*: Apache License v2.0
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*Source control repositories*: https://github.com/miekg/coredns
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*Initial Committers*:
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* Michael Richmond github: mrichmon
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* github: splack
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* Felix Cantournet github: fcantournet
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* github: leelynne
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* Matt Layher github: mdlayher
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* Vasily Vailyev github: pixelbender
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*Infrastructure requirements (CI / CNCF Cluster)*: N/A
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*Issue tracker*: https://github.com/miekg/coredns
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*Website*: https://coredns.io
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*Release methodology and mechanics*: github master. As as young project no method for official releases has been
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established. The current rule is: the master branch is production ready at all times. A more formal release
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process is on its way, the choice to use semver versioning has not yet been made. Precompiled binaries will be
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created by hooking into Caddy's website: https://caddyservers.com where "DNS" will be a download option.
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*Social media accounts*: Twitter: @corednsio
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*Existing sponsorship*: Infoblox contributing developer time to implement CoreDNS->Kubernetes integration component.
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*Existing community*: The community is small, but growing. Current number of twitter following is 100+ (after a
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week of having the twitter account). By aligning ourselves with the Caddy community we hope to leverage Caddy's
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popularity for CoreDNS. By positioning CoreDNS as a better SkyDNS we hope to entice user of SkyDNS to embrace
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CoreDNS.
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*External Dependencies*
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CoreDNS has a hard dependency on Caddy (mholt/caddy), as CoreDNS is a servertype-plugin to it. Technically this
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means we need to patch one source file in the caddy tree, before CoreDNS can be build. Other than that it is
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similar to a normal Go dependency.
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* Go package: mholt/caddy (ASLV2 https://github.com/mholt/caddy/blob/master/LICENSE.txt)
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* Go package: beorn7/perks (MIT https://github.com/beorn7/perks/blob/master/LICENSE)
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* Go package: coreos/etcd (ASLv2 https://github.com/coreos/etcd/blob/master/LICENSE)
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* Go package: flynn/go-shlex (ASLv2 https://github.com/flynn-archive/go-shlex/blob/master/COPYING)
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* Go package: fsnotify/fsnotify (BSD https://github.com/fsnotify/fsnotify/blob/master/LICENSE)
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* Go package: golang/protobuf (BSD https://github.com/golang/protobuf/blob/master/LICENSE)
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* Go package: hashicorp/go-syslog (MIT https://github.com/hashicorp/go-syslog/blob/master/LICENSE)
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* Go package: matttproud/golang_protobuf_extensions (ASLv2 https://github.com/matttproud/golang_protobuf_extensions/blob/master/LICENSE
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* Go package: miekg/dns (BSD https://github.com/miekg/dns/blob/master/LICENSE)
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* Go package: patrickmn/go-cache (MIT https://github.com/patrickmn/go-cache/blob/master/LICENSE)
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* Go package: prometheus/client_golang (ASLv2 https://github.com/prometheus/client_golang/blob/master/LICENSE)
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* Go package: prometheus/client_model (ASLv2 https://github.com/prometheus/client_model/blob/master/LICENSE)
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* Go package: prometheus/common (ASLv2 https://github.com/prometheus/common/blob/master/LICENSE)
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* Go package: prometheus/procfs (ASLv2 https://github.com/prometheus/procfs/blob/master/LICENSE)
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* Go package: ugorji/go (MIT https://github.com/ugorji/go/blob/master/LICENSE)
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* Go package: xenolf/lego (MIT https://github.com/xenolf/lego/blob/master/LICENSE)
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* Go package: golang/x/crypto (BSD https://github.com/golang/crypto/blob/master/LICENSE)
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* Go package: golang/x/net (BSD https://github.com/golang/net/blob/master/LICENSE)
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* Go package: golang/x/sys (BSD https://github.com/golang/sys/blob/master/LICENSE)
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* Go package: natefinch/lumberjack.v2 (MIT https://github.com/natefinch/lumberjack/blob/v2.0/LICENSE)
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* Go package: square/go-jose.v1 (ASLv2 https://github.com/square/go-jose/blob/master/LICENSE)
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* Kubernetes (for CoreDNS -> kubernetes integration) (ASLv2 https://github.com/kubernetes/kubernetes/blob/master/LICENSE)
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*Statement on alignment with CNCF mission*:
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CoreDNS is a focused lightweight DNS server. A microservice philosophy guides the internal design of CoreDNS. Individual DNS functions are provided by discrete, composable plugins that are enabled via runtime configuration.
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CoreDNS can be thought of as a DNS protocol head that can be configured to front various backend data sources. A flexible DNS server is a necessary component to provide “Naming and Discovery” services to containers running in the CNCF distributed system services environment.
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*Comparison with KubeDNS*:
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The incumbent DNS service for kubernetes, “kubedns”, consists of four components:
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* etcd provides a DNS data cache,
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* kube2sky provides the mechanism for updating the etcd data cache,
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* skydns provides the DNS service based on the data cached in etcd,
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* exechealthz provides health-check status.
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Running CoreDNS with kubernetes only requires the coredns component. CoreDNS does not require a separate data cache or update service. CoreDNS includes an optional health-check “middleware” component that can be used for service monitoring.
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CoreDNS provides a cleaner, more extensible codebase as compared to SkyDNS. (Both SkyDNS and CoreDNS were authored by Miek Gieben.)
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CoreDNS is currently being extended to operate directly with kubernetes to access the service data. This “middleware” implementation for CoreDNS provides the same client-facing behavior as KubeDNS. The pipeline-based design of CoreDNS allows easy extension to use any container orchestrator as a DNS data source.
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With the kubernetes middleware, CoreDNS can be considered as an alternative to SkyDNS with lower runtime complexity. Performance testing to compare against SkyDNS is pending.
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