With injected delivery the credentials exist ONLY in PID 1's environment:
the container command is a shell that sources /vault/secrets/<name> and
execs the real server, so the values live in that process and nowhere
else — not in the pod spec, which is the whole point.
mcpd picks its STDIO mode from the server's shape: an explicit command or
a packageName selects `exec`, a bare dockerImage selects `attach`. `exec`
spawns a NEW process inside the container, which never sourced the file
and therefore starts with empty credentials. The server comes up, answers
tools/list, and fails every authenticated call — precisely the silent
empty-token failure this feature exists to prevent.
Seen as `Readiness check (list_datasources) failed: process exited 1` on a
pod whose PID 1 demonstrably held the token (verified via /proc/1/environ:
GRAFANA_URL set, token 46 chars, nothing in the pod spec).
So secretDelivery: injector now forces attach regardless of server shape.
Safe because wrapCommandForInjector execs rather than forks, so PID 1 IS
the server. It also means no bouncer or HTTP shim is needed — mcpd's
PersistentStdio already holds one long-lived connection; it was simply
pointed at the wrong process.
Note this inverts an assumption I had earlier: image-entrypoint servers
were already on the attach path and would have worked; it is the
package-based ones that were broken. gitea remains the sole exception, and
for the unrelated reason that it is distroless and has no shell to source
the file.
Extracts the decision as a pure `chooseStdioMode()` so it can be tested —
it is subtle and fails silently. Six cases pinned, including that env
delivery still execs.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018vybEitX4FykeMatKe5Xki
