fix(cli): support aspect configure with rules_go under bzlmod (#7217)

The rules_go gazelle integration changed in bzlmod such that it now
requires resolving the
[bazel_gazelle_go_repository_config](https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/internal/bzlmod/go_deps.bzl#L653-L672)
repository which contains a cache-able list of the `go_repository`
target data (not the actual targets, just data about them).

With regular gazelle from a `gazelle_binary` target the
`@bazel_gazelle_go_repository_config` repo path is resolved using [a
rule label
attribute](https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/def.bzl#L101-L104)
and [this
hack](https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/internal/go_repository.bzl#L313-L321).
However when we are running gazelle within `aspect configure` we need an
alternate way of resolving this path.

This PR does something similar to the [the go_repository
hack](https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/internal/go_repository.bzl#L313-L321),
except we must launch `bazel info output_base` to get the external
directory.

Fix #760

---

### Changes are visible to end-users: yes

- Searched for relevant documentation and updated as needed: yes
- Breaking change (forces users to change their own code or config): no
- Suggested release notes appear below: yes

The go language in `aspect configure` will now work when rules_go is
under bzlmod.

### Test plan

- Manual testing; please provide instructions so we can reproduce: run
the cli binary on a repo where rules_go is loaded with bzlmod, for
example https://github.com/r0bobo/aspect-cli-issue-760-reproduce

GitOrigin-RevId: aded45cc9e6566447383b193a201255e55e90730

pkg/aspect/configure/BUILD.bazel

@@ -8,6 +8,7 @@ go_library(
         "fix.go",
         "fix-update.go",
         "gazelle.go",
+        "go_deps.go",
         "metaresolver.go",
         "print.go",
         "profiler.go",
@@ -21,7 +22,9 @@ go_library(
         "//gazelle/python",
         "//pkg/aspect/configure/internal/wspace",
         "//pkg/aspecterrors",
+        "//pkg/bazel",
         "//pkg/ioutils",
+        "//pkg/logger",
         "@bazel_gazelle//config:go_default_library",
         "@bazel_gazelle//flag:go_default_library",
         "@bazel_gazelle//label:go_default_library",

pkg/aspect/configure/configure.go

@@ -75,6 +75,17 @@ func (c *Configure) addDefaultLanguages() {
 
 	viper.SetDefault("configure.languages.go", false)
 	if viper.GetBool("configure.languages.go") {
+		if os.Getenv(GO_REPOSITORY_CONFIG_ENV) == "" {
+			goConfigPath, err := determineGoRepositoryConfigPath()
+			if err != nil {
+				log.Fatalf("ERROR: unable to determine go_repository config path: %v", err)
+			}
+
+			if goConfigPath != "" {
+				os.Setenv(GO_REPOSITORY_CONFIG_ENV, goConfigPath)
+			}
+		}
+
 		c.AddLanguage("go", golang.NewLanguage)
 	}
 
@@ -140,6 +151,11 @@ configure:
 		fixArgs = append(fixArgs, "--memprofile="+memprofile)
 	}
 
+	go_repo_config := os.Getenv(GO_REPOSITORY_CONFIG_ENV)
+	if go_repo_config != "" {
+		fixArgs = append(fixArgs, "--repo_config="+go_repo_config)
+	}
+
 	// Append additional args including specific directories to fix.
 	fixArgs = append(fixArgs, args...)
 

pkg/aspect/configure/go_deps.go

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2024 Aspect Build Systems, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package configure
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strings"
+
+	"aspect.build/cli/pkg/bazel"
+	"aspect.build/cli/pkg/ioutils"
+	BazelLog "aspect.build/cli/pkg/logger"
+)
+
+// The @gazelle go_deps extension name.
+// https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/internal/bzlmod/go_deps.bzl#L827
+const GO_DEPS_EXTENSION_NAME = "go_deps"
+
+// The repository name for the gazelle repo_config.
+// https://github.com/bazel-contrib/bazel-gazelle/blob/v0.39.1/internal/bzlmod/go_deps.bzl#L648-L654
+const GO_REPOSITORY_CONFIG_REPO_NAME = "bazel_gazelle_go_repository_config"
+
+// An environment variable to set the full path to the gazelle repo_config
+const GO_REPOSITORY_CONFIG_ENV = GO_REPOSITORY_CONFIG_REPO_NAME
+
+// bazel 8 switches the bzlmod separator to "+"
+// See https://github.com/bazelbuild/bazel/issues/23127
+var BZLMOD_REPO_SEPARATORS = []string{"~", "+"}
+
+func determineGoRepositoryConfigPath() (string, error) {
+	// TODO(jason): look into a store of previous invocations for relevant logs
+	bzl := bazel.WorkspaceFromWd
+
+	var out strings.Builder
+	streams := ioutils.Streams{Stdout: &out, Stderr: nil}
+	if err := bzl.RunCommand(streams, nil, "info", "output_base"); err != nil {
+		return "", fmt.Errorf("unable to locate output_base: %w", err)
+	}
+
+	outputBase := strings.TrimSpace(out.String())
+	if outputBase == "" {
+		return "", fmt.Errorf("unable to locate output_base on path")
+	}
+
+	var goDepsRepoName string
+	for _, sep := range BZLMOD_REPO_SEPARATORS {
+		repoName := fmt.Sprintf("gazelle%s%s%s%s%s/WORKSPACE", sep, sep, GO_DEPS_EXTENSION_NAME, sep, GO_REPOSITORY_CONFIG_REPO_NAME)
+		repoPath := path.Join(outputBase, "external", repoName)
+
+		_, err := os.Stat(repoPath)
+		if err == nil {
+			goDepsRepoName = repoPath
+			break
+		}
+	}
+
+	if goDepsRepoName == "" {
+		// Assume no matches means rules_go is not being used in bzlmod
+		// or the gazelle `go_deps` extension is not being used
+		BazelLog.Infof("No %s found in output_base: %s", GO_REPOSITORY_CONFIG_REPO_NAME, outputBase)
+		return "", nil
+	}
+
+	BazelLog.Infof("Found %s(s): %v", GO_REPOSITORY_CONFIG_REPO_NAME, goDepsRepoName)
+
+	return goDepsRepoName, nil
+}