GitHub Deploy Key Routing

Treat GitHub private repo access as a routing problem, not just a Git problem.

Core rules

• Use one deploy key per private repository unless a machine user is intentionally chosen.
• Use one SSH host alias per key.
• Point each repo remote at the correct alias explicitly.
• Do not rely on a catch-all Host github.com when multiple deploy keys exist.
• Verify SSH first, then Git, then push.
• If automation is involved, fix both the live repo remote and the config/script source that writes it.

Canonical pattern