ci: enhanced linting (#158)

Add a configuration file which makes it much more strict.

Fix shadowed error variables flagged by linter.

Remove CI timeout as its now present in the config.

.github/workflows/golangci-lint.yml

@@ -21,4 +21,3 @@ jobs:
         uses: golangci/golangci-lint-action@aaa42aa0628b4ae2578232a66b541047968fac86 # v6.1.0
         with:
           version: v1.60.3
-          args: --timeout=3m

.golangci.yaml

@@ -0,0 +1,86 @@
+run:
+  timeout: 2m
+
+linters-settings:
+  gosec:
+    excludes:
+      - G601 ## Implicit memory aliasing of items from a range statement - not possible in go 1.22.
+  cyclop:
+    max-complexity: 15
+  nestif:
+    min-complexity: 10
+  govet:
+    settings:
+      shadow:
+        strict: true
+    enable-all: true
+  nolintlint:
+    require-explanation: true
+  godot:
+    scope: all
+  nakedret:
+    max-func-lines: 0
+
+linters:
+  enable-all: true
+  disable:
+    # Spammy / low value
+    - nonamedreturns
+    - varnamelen
+    - exhaustruct
+    - nlreturn
+    - wsl
+    - lll
+    - paralleltest
+    # Duplicate functionality.
+    - funlen
+    - gocognit
+    # Deprecated.
+    - execinquery
+    - gomnd
+    # Good but gets in the way too often.
+    - testpackage
+    # Unknown details about how Artemis works are flagged with TODO's.
+    - godox
+    # Seems to be broken.
+    - depguard
+    # Makes it messy for multiple optional tags.
+    - tagalign
+    # Not needed for go 1.22+.
+    - exportloopref
+    - errchkjson # Duplicate functionality for errcheck.
+
+issues:
+  include:
+    - EXC0012
+    - EXC0014
+  exclude-rules:
+    # Exclude linters which aren't an issue in tests.
+    - path: _test\.go
+      linters:
+        - gochecknoglobals
+        - wrapcheck
+
+    # File mode permissions are fine for constants.
+    - text: "Magic number: 0o\\d+"
+      linters:
+        - mnd
+
+    # Field alignment in tests isn't a performance issue.
+    - text: fieldalignment
+      path: _test\.go
+
+    # Dynamic errors can provide useful context.
+    - text: "do not define dynamic errors, use wrapped static errors instead:"
+      linters:
+        - err113
+
+    # We need to use the `err` named return for error handling.
+    - text: 'named return "err" with type "error" found'
+      linters:
+        - nonamedreturns
+
+    # Interface casting is fine in mock.
+    - path: mock_test\.go
+      linters:
+        - forcetypeassert

reaper.go

@@ -239,7 +239,7 @@ func (r *reaper) handle(conn net.Conn) {
 		default:
 			if err := r.addFilter(msg); err != nil {
 				logger.Error("add filter", fieldError, err)
-				if _, err := conn.Write(ackResponse); err != nil {
+				if _, err = conn.Write(ackResponse); err != nil {
 					logger.Error("ack write", fieldError, err)
 				}
 				continue

reaper_test.go

@@ -578,7 +578,7 @@ func TestReapContainer(t *testing.T) {
 
 	t.Cleanup(func() {
 		// Ensure the container was / is removed.
-		err := cli.ContainerRemove(ctx, resp.ID, container.RemoveOptions{})
+		err = cli.ContainerRemove(ctx, resp.ID, container.RemoveOptions{})
 		require.Error(t, err)
 		require.True(t, errdefs.IsNotFound(err))
 	})
@@ -607,7 +607,7 @@ func TestReapNetwork(t *testing.T) {
 
 	t.Cleanup(func() {
 		// Ensure the network was / is removed.
-		err := cli.NetworkRemove(ctx, resp.ID)
+		err = cli.NetworkRemove(ctx, resp.ID)
 		require.Error(t, err)
 		require.True(t, errdefs.IsNotFound(err))
 	})
@@ -631,7 +631,7 @@ func TestReapVolume(t *testing.T) {
 
 	t.Cleanup(func() {
 		// Ensure the volume was / is removed.
-		err := cli.VolumeRemove(ctx, resp.Name, false)
+		err = cli.VolumeRemove(ctx, resp.Name, false)
 		require.Error(t, err)
 		require.True(t, errdefs.IsNotFound(err))
 	})
@@ -667,7 +667,7 @@ func TestReapImage(t *testing.T) {
 			return
 		}
 		var result types.BuildResult
-		err := json.Unmarshal(*msg.Aux, &result)
+		err = json.Unmarshal(*msg.Aux, &result)
 		require.NoError(t, err)
 		imageID = result.ID
 	}
@@ -677,8 +677,8 @@ func TestReapImage(t *testing.T) {
 
 	t.Cleanup(func() {
 		// Ensure the image was / is removed.
-		resp, err := cli.ImageRemove(ctx, imageID, image.RemoveOptions{})
-		require.Error(t, err)
+		resp, errc := cli.ImageRemove(ctx, imageID, image.RemoveOptions{})
+		require.Error(t, errc)
 		require.Empty(t, resp)
 	})