Nothing, Deprecated

[xiaojunxiang2023]

Summary

Make env_vars passed to Sandbox.create(...) visible to later
commands.run(...) / run_code(...), by treating them as sandbox runtime
metadata and syncing them into the guest through envd's native
POST :49983/init at create/restore time.

This is an independent redesign of the previously rejected #484. It is based on
current master (single commit, no dependency on #484) and drops the
rootfs/profile/bind-mount injection entirely, following the direction requested
in that review.

Background

Previously env_vars from the SDK were dropped at the CubeAPI layer
(containers: vec![]), so they never reached the guest and were invisible to
commands.run. #484 tried to fix this by writing
/etc/profile.d/99-cube-create-env.sh into the guest rootfs, which was rejected
as too hacky and not a runtime-layer solution.

Approach

env_vars are carried as runtime metadata and injected into envd, the same way
the upstream E2B orchestrator does it (POST /init -> envd defaults.EnvVars).
envd then merges them when it spawns any process, so the precedence
create env < per-command env holds for every process model, not just login
shells.

• CubeAPI (sandboxes.rs): serialize env_vars into the
  cube.master.sandbox.create_env_vars annotation (JSON object) instead of
  dropping them.
• CubeMaster: the annotation is forwarded to Cubelet via the existing
  cube.master prefix passthrough, and stripped in
  normalizeStoredTemplateRequest on template commit so per-instance secrets
  are never persisted into template snapshots.
• Cubelet (envd_init.go): after the readiness probe, POST /init to
  <sandbox-ip>:49983 with the create env_vars (bounded retry). envd stores
  them additively (defaults.EnvVars.Store), so env already present in the
  guest runtime (e.g. template env) is preserved.

No changes to envd (pinned e2b-dev/infra@2026.16); this only wires up the
client side that CubeSandbox was missing compared to the official platform.

How this addresses the previous review

Review concern (#484)	This PR
Solve env sync at the sandbox/runtime layer, not via shell profile	envd /init -> defaults.EnvVars, merged at the exec layer for every spawned process
Don't persist secrets into rootfs/profile files	Nothing written to disk; annotation is in-memory metadata and stripped on template commit
Profile export overrides per-command env= (broken precedence)	envd applies defaults.EnvVars first, per-command last -> per-command correctly overrides
Shell parsing / injection risk	No shell script generated; env passed as a JSON map
Coupling across start/restore/netfile/hostdir/rootfs	One new file + one hook after the probe + annotation passthrough + commit strip
Tied to /bin/bash -l + /etc/profile.d, not general	Independent of shell type / entrypoint; applies to all envd-spawned processes
API/Master propagation is a useful part	Kept (CubeAPI -> annotation -> CubeMaster passthrough)
Don't merge Cubelet profile/rootfs/bind-mount injection	Removed entirely

Precedence

template env < create env < per-command env.
Template env already lives in the guest runtime today; /init only adds the
create-time keys on top (same-key create overrides template), and envd's
per-command env still overrides both. Docker image ENV is not surfaced to
commands.run, matching upstream envd behavior (see e2b-dev/infra#2268).

Tests

Unit tests were added at every layer (all green):

• Cubelet envd_init_test.go: no-annotation no-op, invalid-JSON error,
  empty-IP error, success path asserting the envVars/timestamp sent to a
  stub /init, and retry-then-succeed.
• CubeMaster store_test.go: normalizeStoredTemplateRequest strips the
  create-env annotation on commit while preserving unrelated annotations.
• CubeAPI sandboxes.rs: annotation key uses the cube.master prefix,
  absent/empty maps are skipped, and a non-empty map serializes to a JSON
  object.

Build/format verified via the project toolchain: cargo build/cargo test,
go build/go vet, and gofmt + cargo fmt clean.

Notes

• The /init body only sends envVars + timestamp; all other fields are
  omitted, so it never clears envd's access token, default user/workdir, etc.
  (CubeSandbox runs envd without an access token, so first-time /init is
  authorized.)
• Covers create and restore-from-snapshot (the normal create-from-template
  path runs the same probe + sync). Across pause/resume of the same VM the env
  persists in guest memory, so no extra resume hook is required.