Use depguard linter to forbid dependencies

Introduce the depguard linter to forbid required dependencies in the
submodules. This is a clean way to achieve what we had before in the
go.mod by using a replacement and pointing the forbidden package to a
virtual non-existent directory "FORBIDDEN_DEPENDENCY". Now, if a package
requires a forbidden dependency, the linter will fail, rather than
having Go fail to compile/fetch dependencies.

Signed-off-by: Ivan Valdes <[email protected]>

Author: ivanvc

api/go.mod

@@ -26,13 +26,3 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250825161204-c5933d9347a5 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
-
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-replace (
-	go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/api/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/pkg/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/tests/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/v3 => ./FORBIDDEN_DEPENDENCY
-)

client/v3/go.mod

@@ -46,12 +46,3 @@ replace (
 	go.etcd.io/etcd/api/v3 => ../../api
 	go.etcd.io/etcd/client/pkg/v3 => ../pkg
 )
-
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-replace (
-	go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/pkg/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/tests/v3 => ./FORBIDDEN_DEPENDENCY
-)

etcdctl/go.mod

@@ -54,11 +54,3 @@ replace (
 	go.etcd.io/etcd/client/v3 => ../client/v3
 	go.etcd.io/etcd/pkg/v3 => ../pkg
 )
-
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-replace (
-	go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/tests/v3 => ./FORBIDDEN_DEPENDENCY
-)

etcdutl/go.mod

@@ -12,14 +12,6 @@ replace (
 	go.etcd.io/etcd/server/v3 => ../server
 )
 
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-replace (
-	go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/tests/v3 => ./FORBIDDEN_DEPENDENCY
-)
-
 require (
 	github.com/coreos/go-semver v0.3.1
 	github.com/dustin/go-humanize v1.0.1

pkg/go.mod

@@ -32,14 +32,3 @@ require (
 )
 
 replace go.etcd.io/etcd/client/pkg/v3 => ../client/pkg
-
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-// Etcd contains lots of packages and dependency relationship.
-// Shouldn't import unnecessary dependencies
-replace (
-	go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/api/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/tests/v3 => ./FORBIDDEN_DEPENDENCY
-	go.etcd.io/etcd/v3 => ./FORBIDDEN_DEPENDENCY
-)

server/go.mod

@@ -82,9 +82,3 @@ replace (
 	go.etcd.io/etcd/client/v3 => ../client/v3
 	go.etcd.io/etcd/pkg/v3 => ../pkg
 )
-
-// Bad imports are sometimes causing attempts to pull that code.
-// This makes the error more explicit.
-replace go.etcd.io/etcd => ./FORBIDDEN_DEPENDENCY
-
-replace go.etcd.io/tests/v3 => ./FORBIDDEN_DEPENDENCY

tools/.golangci.yaml

@@ -3,6 +3,7 @@ version: "2"
 linters:
   default: none
   enable: # please keep this alphabetized
+    - depguard # Implement forbidden dependencies
     - errorlint
     - ineffassign
     - nakedret
@@ -17,6 +18,67 @@ linters:
     - usetesting
     - whitespace
   settings:
+    depguard:
+      rules:
+        api:
+          list-mode: lax
+          files:
+            # Check files inside the api module/directory, but skip the
+            # server/etcdserver/api directory. Note that this is configured
+            # this way as depguard doesn't support relative paths. The path
+            # that it uses is absolute where it runs, so we need ** at the
+            # beginning of the path.
+            # Refer to: https://github.com/OpenPeeDeeP/depguard?tab=readme-ov-file#config
+            # > Should always prefix a file glob with **/ as files are matched
+            # > against absolute paths.
+            # Could be simplified if they resolve issue:
+            # https://github.com/OpenPeeDeeP/depguard/issues/54
+            - '**/api/**/*.go'
+            - '!**/server/etcdserver/api/**/*.go'
+          deny:
+            - pkg: go.etcd.io/etcd/api/v3$
+            - pkg: go.etcd.io/etcd/pkg/v3
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
+        client:
+          list-mode: lax
+          files:
+            - "**/client/v3/**/*.go"
+          deny:
+            - pkg: go.etcd.io/etcd/pkg/v3
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
+        etcdctl:
+          list-mode: lax
+          files:
+            - "**/etcdctl/**/*.go"
+          deny:
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
+        etcdutl:
+          list-mode: lax
+          files:
+            - "**/etcdutl/**/*.go"
+          deny:
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
+        server:
+          list-mode: lax
+          files:
+            - "**/server/**/*.go"
+          deny:
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
+        pkg:
+          list-mode: lax
+          files:
+            - "**/pkg/**/*.go"
+            - "!**/client/pkg/**/*.go"
+            - "!**/tools/rw-heatmaps/pkg/**/*.go"
+          deny:
+            - pkg: go.etcd.io/etcd/api/v3
+            - pkg: go.etcd.io/etcd/v3
+            - pkg: go.etcd.io/tests/v3
     nakedret:
       # Align with https://github.com/alexkohler/nakedret/blob/v1.0.2/cmd/nakedret/main.go#L10
       max-func-lines: 5