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Investigate: Auto-Detect Git Identity from Host

IMPLEMENTATION RULES: Before implementing this plan, read and follow:

Status: Backlog​

Goal: Automatically detect the developer's git name and email from the host machine so the devcontainer never shows vscode@localhost.

Priority: High — every new user sees a broken git identity on first start

Last Updated: 2026-04-07

Related: INVESTIGATE-simplify-initial-dct-experience.md

Problem​

On first container start, git identity shows:

✅ Git identity detected:
   Email:    vscode@localhost

This is the container default — not the developer's real identity. Commits made with this identity are attributed to vscode@localhost, which causes problems with GitHub/Azure DevOps.

The startup warns about it but tells the user to "run dev-setup" which requires navigating a menu. Most users ignore it and commit with the wrong identity.

What Already Exists​

Entrypoint reads host git identity files​

image/entrypoint.sh (lines 62-76) already looks for:

  • .devcontainer.secrets/env-vars/.git-host-name
  • .devcontainer.secrets/env-vars/.git-host-email

If these files exist, it applies them with git config --global. The files are expected to be written by an initializeCommand — but the current initializeCommand only captures hostname, not git identity.

Host has the git config​

On the developer's host machine, git config user.name and git config user.email are almost always configured (required for any git work). The data exists — we just need to capture it.

Proposed Solution​

Extend the existing initializeCommand to also capture git identity:

"initializeCommand": "mkdir -p .devcontainer.secrets/env-vars && hostname -s > .devcontainer.secrets/env-vars/.host-hostname 2>/dev/null || hostname > .devcontainer.secrets/env-vars/.host-hostname 2>/dev/null || true && git config user.name > .devcontainer.secrets/env-vars/.git-host-name 2>/dev/null || true && git config user.email > .devcontainer.secrets/env-vars/.git-host-email 2>/dev/null || true"

This runs on the host before the container starts. The entrypoint already reads these files and applies them.

What changes​

BeforeAfter
Container starts with vscode@localhostContainer starts with host's git identity
User must manually configure via dev-setupAutomatic — zero configuration
.git-host-name / .git-host-email files never createdCreated by initializeCommand on every start

Cross-platform​

Platformgit config user.name works?
macOSYes — git is pre-installed or via Xcode CLI tools
LinuxYes — git is standard
Windows (Git Bash)Yes
Windows (PowerShell)Yes — if Git for Windows is installed
Windows (WSL2)Yes — if git is installed in WSL

The || true ensures it doesn't break if git isn't configured on the host.

Questions to Answer​

  1. initializeCommand length — it's getting long (hostname + git name + git email). Should we move it to a script file? But the script needs to exist before the container starts — it's in the workspace, so it should work.

  2. What if the host has no git config? — Files are empty or don't exist. Entrypoint falls back to current behavior (vscode@localhost). No worse than today.

  3. What about users with different git identities per repo? — git config user.name without --global reads the repo-level config first, then global. If the user has a repo-specific identity, that's what gets captured. This is correct behavior.

  4. Privacy — The git identity is stored in .devcontainer.secrets/ which is gitignored. It's also the same identity that would be in git commits — not a new exposure.

  5. Should we also capture the git signing key? — Future enhancement, not needed for the identity problem.

Alternative: Use remoteEnv to pass git config​

We could add to remoteEnv:

"DEV_HOST_GIT_NAME": "${localEnv:GIT_AUTHOR_NAME}",
"DEV_HOST_GIT_EMAIL": "${localEnv:GIT_AUTHOR_EMAIL}"

But GIT_AUTHOR_NAME and GIT_AUTHOR_EMAIL are rarely set as env vars. They're usually in ~/.gitconfig, not the environment. So ${localEnv:...} would be empty for most users. The git config command in initializeCommand is the reliable source.

Implementation Estimate​

This is a small change:

  1. Extend initializeCommand in devcontainer-user-template.json (one line)
  2. The entrypoint already handles the files — no code changes needed
  3. Test on Mac (verify git identity is captured and applied)

The entrypoint code at lines 62-76 is already written and tested. We just need to create the files it reads.

Next Steps​

  • Extend initializeCommand to capture git config user.name and git config user.email
  • Test: fresh install → container starts → git identity shows real name/email
  • Test: host has no git config → graceful fallback to vscode@localhost
  • Consider moving initializeCommand to a script file (getting long)
  • Update startup message — remove "Git identity not configured" warning when identity is auto-detected