refactor(runway): compose the checkout git env from gitexec

runGit in the Runway server's checkout provisioning kept its own copy of the scrubbed-plus-transport environment. Build it through gitexec.Env instead — the same source the merger uses — so provisioning and merging assemble an identical environment from one definition.

This also closes a gap the two hand-written copies had already opened: provisioning omitted GIT_ATTR_NOSYSTEM and the no-pager/no-editor settings the merge path sets, so a system gitattributes file could influence the initial checkout but not later merge operations. Both now run under the same scrub set.

Author: behinddwalls

service/runway/server/BUILD.bazel

@@ -28,6 +28,7 @@ go_library(
         "//platform/extension/consumergate/noop:go_default_library",
         "//platform/extension/messagequeue:go_default_library",
         "//platform/extension/messagequeue/mysql:go_default_library",
+        "//platform/git/exec:go_default_library",
         "//runway/controller:go_default_library",
         "//runway/controller/dlq:go_default_library",
         "//runway/controller/merge:go_default_library",

service/runway/server/checkout.go

@@ -26,6 +26,7 @@ import (
 
 	"go.uber.org/zap"
 
+	gitexec "github.com/uber/submitqueue/platform/git/exec"
 	gitmerger "github.com/uber/submitqueue/runway/extension/merger/git"
 )
 
@@ -190,8 +191,9 @@ func setLocalConfig(checkoutPath, key, value string) error {
 }
 
 // runGit invokes the pinned git in dir with an environment scrubbed of ambient
-// configuration but retaining what is needed to reach a remote — the same split
-// the merger draws, so provisioning and merging authenticate identically.
+// configuration but retaining what is needed to reach a remote. It composes that
+// environment through gitexec.Env, the same source the merger uses, so
+// provisioning and merging authenticate — and behave — identically.
 func runGit(ctx context.Context, runtime gitmerger.GitRuntime, dir string, args ...string) ([]byte, error) {
 	full := append([]string{
 		"--exec-path=" + runtime.ExecPath,
@@ -200,27 +202,16 @@ func runGit(ctx context.Context, runtime gitmerger.GitRuntime, dir string, args
 
 	cmd := exec.CommandContext(ctx, runtime.Executable, full...)
 	cmd.Dir = dir
-	cmd.Env = []string{
-		"HOME=" + filepath.Join(dir, ".submitqueue-git-home"),
-		"GIT_CONFIG_NOSYSTEM=1",
-		"GIT_CONFIG_GLOBAL=" + os.DevNull,
-		"GIT_TERMINAL_PROMPT=0",
-		"GIT_EXEC_PATH=" + runtime.ExecPath,
-		"GIT_TEMPLATE_DIR=" + runtime.TemplateDir,
-		"LC_ALL=C",
-		"LANG=C",
-	}
-	for _, name := range []string{
-		"PATH", "SSH_AUTH_SOCK", "SSH_AGENT_PID",
-		"GIT_SSH", "GIT_SSH_COMMAND", "GIT_SSH_VARIANT",
-		"GIT_SSL_CAINFO", "GIT_SSL_CAPATH", "SSL_CERT_DIR", "SSL_CERT_FILE",
-		"HTTP_PROXY", "HTTPS_PROXY", "NO_PROXY",
-		"http_proxy", "https_proxy", "no_proxy",
-	} {
-		if v, ok := os.LookupEnv(name); ok {
-			cmd.Env = append(cmd.Env, name+"="+v)
-		}
-	}
+	cmd.Env = gitexec.Env(gitexec.EnvOptions{
+		Transport: true,
+		Literal: []string{
+			"HOME=" + filepath.Join(dir, ".submitqueue-git-home"),
+			"GIT_EXEC_PATH=" + runtime.ExecPath,
+			"GIT_TEMPLATE_DIR=" + runtime.TemplateDir,
+			"LC_ALL=C",
+			"LANG=C",
+		},
+	})
 
 	var stdout, stderr bytes.Buffer
 	cmd.Stdout = &stdout