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97 changes: 97 additions & 0 deletions Makefile.ocp
Original file line number Diff line number Diff line change
@@ -0,0 +1,97 @@
# Makefile.ocp — OpenShift plugin management for CoreDNS
#
# Usage:
# make -f Makefile.ocp generate-plugins # prune plugins and regenerate
# make -f Makefile.ocp verify-plugins # CI check: fail if tree is dirty
#
# After an upstream rebase:
# 1. (Optional) Add new plugins to openshift-plugins.cfg if needed
# 2. Run: make -f Makefile.ocp generate-plugins
# 3. Commit the result

OPENSHIFT_PLUGINS_CFG := openshift-plugins.cfg
PLUGIN_CFG := plugin.cfg
PLUGIN_DIR := plugin

# Infrastructure directories under plugin/ that are never plugins.
INFRA_DIRS := pkg test deprecated import

# Plugin directories that are NOT registered in openshift-plugins.cfg but
# are imported as code dependencies by kept plugins. Update this list if
# a kept plugin gains a new cross-plugin import after an upstream rebase.
#
# debug — imported by forward
# dnstap — imported by forward
# etcd — etcd/msg imported by kubernetes
# metadata — imported by cache, kubernetes, forward
# transfer — imported by kubernetes
# whoami — imported by bufsize (tests)
# erratic — imported by ready (tests)
DEP_DIRS := debug dnstap etcd metadata transfer whoami erratic

.PHONY: generate-plugins
generate-plugins:
@echo "==> Overwriting $(PLUGIN_CFG) with $(OPENSHIFT_PLUGINS_CFG)"
cp $(OPENSHIFT_PLUGINS_CFG) $(PLUGIN_CFG)
@echo "==> Removing unused plugin directories"
@$(call remove-unused-plugins)
@echo "==> Regenerating plugin Go files"
go generate coredns.go
@echo "==> Tidying modules"
go mod tidy
@echo "==> Vendoring dependencies"
go mod vendor
@echo "==> Done. Review changes with 'git diff --stat'"
Comment on lines +43 to +44

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During the rebase process, we run go mod vendor and commit the vendored files as a separate step — this is the "Vendor required modules" carry commit (coredns@358bd8f). So I would omit go mod vendor in generate-plugins and put this "reduce dependencies" commit before the "Vendor required modules" commit. The rebase process would be like this:

  1. Rebase on upstream.
    • This step could pull in new plugins that need to be removed. That is, the list of plugins to remove can change during a rebase. However, the list of plugins to keep is static, with respect to a rebase.
  2. Start applying carry commits.
  3. When you reach the "reduce dependencies" commit, apply it, run make generate-plugins , and commit the result.
  4. Next, apply the "Vendor required modules" commit, run go mod vendor, and commit the results.
  5. Continue applying other carry commits.


.PHONY: verify-plugins
verify-plugins:
@echo "==> Verifying plugin tree matches $(OPENSHIFT_PLUGINS_CFG)"
@diff -q $(OPENSHIFT_PLUGINS_CFG) $(PLUGIN_CFG) || \
(echo "ERROR: $(PLUGIN_CFG) does not match $(OPENSHIFT_PLUGINS_CFG)"; exit 1)
@$(call check-no-unused-plugins)
@echo "==> Plugin tree is clean"

# All directories that must be preserved: infrastructure, active plugins
# (from openshift-plugins.cfg), and code-dependency plugins (DEP_DIRS).
define kept-plugin-dirs
$$(grep -v '^\s*#' $(OPENSHIFT_PLUGINS_CFG) | grep -v '^\s*$$' | cut -d: -f2 | grep -v '/')
endef

# remove-unused-plugins deletes plugin/<name>/ directories not in the
# kept set (active plugins + DEP_DIRS + INFRA_DIRS).
define remove-unused-plugins
kept=$(kept-plugin-dirs); \
for dir in $(PLUGIN_DIR)/*/; do \
name=$$(basename "$$dir"); \
skip=false; \
for s in $(INFRA_DIRS) $(DEP_DIRS); do \
if [ "$$name" = "$$s" ]; then skip=true; break; fi; \
done; \
if $$skip; then continue; fi; \
if echo "$$kept" | grep -qx "$$name"; then continue; fi; \
echo " removing $(PLUGIN_DIR)/$$name"; \
rm -rf "$$dir"; \
done
endef

# check-no-unused-plugins fails if any plugin directories exist that
# should have been removed.
define check-no-unused-plugins
kept=$(kept-plugin-dirs); \
stale=""; \
for dir in $(PLUGIN_DIR)/*/; do \
name=$$(basename "$$dir"); \
skip=false; \
for s in $(INFRA_DIRS) $(DEP_DIRS); do \
if [ "$$name" = "$$s" ]; then skip=true; break; fi; \
done; \
if $$skip; then continue; fi; \
if echo "$$kept" | grep -qx "$$name"; then continue; fi; \
stale="$$stale $$name"; \
done; \
if [ -n "$$stale" ]; then \
echo "ERROR: unused plugin directories found:$$stale"; \
echo "Run 'make -f Makefile.ocp generate-plugins' to fix."; \
exit 1; \
fi
endef
51 changes: 51 additions & 0 deletions OPENSHIFT.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
# OpenShift CoreDNS Fork

This is the OpenShift fork of [CoreDNS](https://coredns.io). It is deployed
and managed by the
[cluster-dns-operator](https://github.com/openshift/cluster-dns-operator).

## Plugin management

The operator generates the CoreDNS Corefile and only uses a subset of upstream
plugins. Unused plugins are removed to reduce the binary size, dependency
footprint, and attack surface.

The file `openshift-plugins.cfg` is the source of truth for the kept plugin
set. It uses the same `name:package` format as the upstream `plugin.cfg`.

### Regenerating after a rebase

After rebasing onto a new upstream version:

```
make -f Makefile.ocp generate-plugins
```

This will:

1. Overwrite `plugin.cfg` with `openshift-plugins.cfg`
2. Remove plugin directories under `plugin/` that are not needed
3. Regenerate the Go files (`core/plugin/zplugin.go`, `core/dnsserver/zdirectives.go`)
4. Run `go mod tidy` and `go mod vendor`

Review the result with `git diff --stat`, then commit.

### Adding or removing a plugin

Edit `openshift-plugins.cfg`, then run `make -f Makefile.ocp generate-plugins`.

If a kept plugin imports another plugin as a Go package (not as a registered
Corefile directive), that dependency directory must be listed in the `DEP_DIRS`
variable in `Makefile.ocp`. The build will fail with a clear error if a
dependency is missing.

### CI verification

The pipeline should run:

```
make -f Makefile.ocp verify-plugins
```

This checks that `plugin.cfg` matches `openshift-plugins.cfg` and that no
unused plugin directories are present.
42 changes: 0 additions & 42 deletions core/dnsserver/zdirectives.go
Original file line number Diff line number Diff line change
Expand Up @@ -10,60 +10,18 @@ package dnsserver
// (after) them during a request, but they must not
// care what plugin above them are doing.
var Directives = []string{
"root",
"metadata",
"geoip",
"cancel",
"tls",
"quic",
"timeouts",
"multisocket",
"reload",
"nsid",
"bufsize",
"bind",
"debug",
"trace",
"ready",
"health",
"pprof",
"prometheus",
"errors",
"log",
"dnstap",
"local",
"dns64",
"acl",
"any",
"chaos",
"loadbalance",
"tsig",
"ocp_dnsnameresolver",
"cache",
"rewrite",
"header",
"dnssec",
"autopath",
"minimal",
"template",
"transfer",
"hosts",
"route53",
"azure",
"clouddns",
"k8s_external",
"kubernetes",
"file",
"auto",
"secondary",
"etcd",
"loop",
"forward",
"grpc",
"erratic",
"whoami",
"on",
"sign",
"view",
"nomad",
}
42 changes: 0 additions & 42 deletions core/plugin/zplugin.go
Original file line number Diff line number Diff line change
Expand Up @@ -4,61 +4,19 @@ package plugin

import (
// Include all plugins.
_ "github.com/coredns/caddy/onevent"
_ "github.com/coredns/coredns/plugin/acl"
_ "github.com/coredns/coredns/plugin/any"
_ "github.com/coredns/coredns/plugin/auto"
_ "github.com/coredns/coredns/plugin/autopath"
_ "github.com/coredns/coredns/plugin/azure"
_ "github.com/coredns/coredns/plugin/bind"
_ "github.com/coredns/coredns/plugin/bufsize"
_ "github.com/coredns/coredns/plugin/cache"
_ "github.com/coredns/coredns/plugin/cancel"
_ "github.com/coredns/coredns/plugin/chaos"
_ "github.com/coredns/coredns/plugin/clouddns"
_ "github.com/coredns/coredns/plugin/debug"
_ "github.com/coredns/coredns/plugin/dns64"
_ "github.com/coredns/coredns/plugin/dnssec"
_ "github.com/coredns/coredns/plugin/dnstap"
_ "github.com/coredns/coredns/plugin/erratic"
_ "github.com/coredns/coredns/plugin/errors"
_ "github.com/coredns/coredns/plugin/etcd"
_ "github.com/coredns/coredns/plugin/file"
_ "github.com/coredns/coredns/plugin/forward"
_ "github.com/coredns/coredns/plugin/geoip"
_ "github.com/coredns/coredns/plugin/grpc"
_ "github.com/coredns/coredns/plugin/header"
_ "github.com/coredns/coredns/plugin/health"
_ "github.com/coredns/coredns/plugin/hosts"
_ "github.com/coredns/coredns/plugin/k8s_external"
_ "github.com/coredns/coredns/plugin/kubernetes"
_ "github.com/coredns/coredns/plugin/loadbalance"
_ "github.com/coredns/coredns/plugin/local"
_ "github.com/coredns/coredns/plugin/log"
_ "github.com/coredns/coredns/plugin/loop"
_ "github.com/coredns/coredns/plugin/metadata"
_ "github.com/coredns/coredns/plugin/metrics"
_ "github.com/coredns/coredns/plugin/minimal"
_ "github.com/coredns/coredns/plugin/multisocket"
_ "github.com/coredns/coredns/plugin/nomad"
_ "github.com/coredns/coredns/plugin/nsid"
_ "github.com/coredns/coredns/plugin/pprof"
_ "github.com/coredns/coredns/plugin/quic"
_ "github.com/coredns/coredns/plugin/ready"
_ "github.com/coredns/coredns/plugin/reload"
_ "github.com/coredns/coredns/plugin/rewrite"
_ "github.com/coredns/coredns/plugin/root"
_ "github.com/coredns/coredns/plugin/route53"
_ "github.com/coredns/coredns/plugin/secondary"
_ "github.com/coredns/coredns/plugin/sign"
_ "github.com/coredns/coredns/plugin/template"
_ "github.com/coredns/coredns/plugin/timeouts"
_ "github.com/coredns/coredns/plugin/tls"
_ "github.com/coredns/coredns/plugin/trace"
_ "github.com/coredns/coredns/plugin/transfer"
_ "github.com/coredns/coredns/plugin/tsig"
_ "github.com/coredns/coredns/plugin/view"
_ "github.com/coredns/coredns/plugin/whoami"

_ "github.com/openshift/coredns-ocp-dnsnameresolver"
)
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