Dependencies

go.mod declares roughly 35 direct dependencies and another ~150 indirect ones. This page lists the direct ones grouped by what they're for. The Go module path and a short note are given for each.

DNS protocol

Module	Used by	Note
github.com/miekg/dns	Everything	The DNS message library that CoreDNS is built on. Maintained by Miek Gieben (project founder).
github.com/dnstap/golang-dnstap	plugin/dnstap	dnstap framing
github.com/farsightsec/golang-framestream	plugin/dnstap (transitive)	Frame-streams encoder/decoder used by dnstap

Server framework

Module	Used by	Note
github.com/coredns/caddy	core/dnsserver/, coremain/	The CoreDNS-maintained fork of Caddy v1. Hosts the server type.

Encrypted transports

Module	Used by	Note
github.com/quic-go/quic-go	core/dnsserver/server_quic.go, server_https3.go	DoQ and DoH3
github.com/quic-go/qpack (indirect)	(HTTP/3)	HPACK-for-QUIC
github.com/pires/go-proxyproto	plugin/proxyproto, server constructors	PROXY protocol v1/v2
golang.org/x/crypto	plugin/pkg/tls, others	TLS curves and ciphers
golang.org/x/net	Various	HTTP/2 push, networking utilities

Metrics, tracing, observability

Module	Used by	Note
github.com/prometheus/client_golang	plugin/metrics and per-plugin metrics	Prometheus client
github.com/prometheus/client_model, prometheus/common, prometheus/exporter-toolkit	plugin/metrics	Prometheus support libraries
github.com/openzipkin/zipkin-go, openzipkin-contrib/zipkin-go-opentracing	plugin/trace	Zipkin backend
github.com/opentracing/opentracing-go	plugin/trace	OpenTracing API used by the trace plugin
github.com/grpc-ecosystem/grpc-opentracing	plugin/trace	OpenTracing for gRPC
github.com/DataDog/dd-trace-go/v2	plugin/trace	Datadog tracing backend

Backends

Module	Used by	Note
k8s.io/api, apimachinery, client-go, klog/v2	plugin/kubernetes	Kubernetes service-discovery
sigs.k8s.io/mcs-api	plugin/kubernetes	Multi-Cluster Service API
go.etcd.io/etcd/api/v3, etcd/client/v3	plugin/etcd	etcd v3 client
github.com/aws/aws-sdk-go-v2, config, credentials, feature/ec2/imds	plugin/route53, plugin/secretsmanager (DNSSEC keys), plugin/clouddns (transitively)	AWS SDK v2 base
github.com/aws/aws-sdk-go-v2/service/route53	plugin/route53	Route53 API
github.com/aws/aws-sdk-go-v2/service/secretsmanager	plugin/dnssec	Pulls DNSSEC keys
github.com/Azure/azure-sdk-for-go, Azure/go-autorest/...	plugin/azure	Azure DNS
google.golang.org/api	plugin/clouddns	Google Cloud DNS
github.com/hashicorp/nomad/api	plugin/nomad	Nomad service discovery

gRPC

Module	Used by	Note
google.golang.org/grpc	plugin/grpc, plugin/grpc_server, core/dnsserver/server_grpc.go	gRPC server and client
google.golang.org/protobuf	Generated code in pb/	Protobuf runtime

Geo and expression

Module	Used by	Note
github.com/oschwald/geoip2-golang/v2	plugin/geoip	MaxMind GeoIP2 lookup
github.com/expr-lang/expr	plugin/rewrite, plugin/view	Expression evaluation language

Utilities

Module	Used by	Note
github.com/apparentlymart/go-cidr	plugin/acl, plugin/view	CIDR helpers
github.com/infobloxopen/go-trees	plugin/file, plugin/auto	Red-black tree used in zone matching
github.com/hashicorp/golang-lru/v2	plugin/cache, plugin/dnssec, plugin/proxyproto	LRU caches
github.com/go-logr/logr	Plugins that bridge to klog	logr API
go.uber.org/automaxprocs	coremain	Auto-detects container CPU limits

Test-only dependencies

Module	Used by
github.com/stretchr/testify	Most *_test.go files
golang.org/x/sys	Tests that need raw syscalls

Why these specific cloud SDKs?

CoreDNS includes Route53, Azure DNS, Cloud DNS, and Nomad because each has a community-maintained backend plugin that depends on it. The SDKs are large; pulling them in raises the binary size and the dependency churn. CoreDNS counters this with:

• Dependabot for prompt SDK upgrades.
• coredns-auto-go-mod-tidy[bot] to keep go.sum clean.
• The make.gen workflow keeps generated registrations consistent.
• Plugins that are not loaded into a Corefile still get linked into the binary (CoreDNS does not currently support build-time pruning of unused plugins).

If a deployment doesn't need cloud backends, the project tradition is to maintain a slim build by editing plugin.cfg to remove unwanted entries, running make gen, and rebuilding.

License

The LICENSE file at the repo root is Apache 2.0. All direct dependencies are Apache 2.0, BSD-3, MIT, MPL-2.0, or compatible per the OSSF Scorecard checks.