feat: support updating egress proxy secret envs for key rotation

[sjmiller609]

Summary

• Adds PATCH /instances/{id} API endpoint for updating mutable instance properties
• Adds UpdateInstanceRules() to egress proxy service for live header inject rule updates
• Adds UpdateInstance() to instance manager with UpdateInstanceRequest type
• Enables credential/secret key rotation without instance restart — the host-side egress proxy recompiles header inject rules in-place with the new secret values
• Extends egress proxy integration test to verify key rotation flow end-to-end

How it works

The egress proxy runs on the host and intercepts outbound HTTPS traffic from the guest. Credential secrets are never exposed to the guest — the guest only sees mock placeholder values. When secrets are updated via the API:

1. New env values are merged into instance metadata
2. Credential env bindings are re-validated
3. Header inject rules are recompiled from the updated env + existing credential policies
4. The egress proxy's in-memory rules are swapped atomically via UpdateInstanceRules()

No guest restart or signaling is needed because the proxy operates entirely on the host side.

Test plan

• Extended TestEgressProxyRewritesHTTPSHeaders integration test to include:
  • Update credential env value via UpdateInstance()
  • Verify guest-visible env still shows mock placeholder (secrets never leak)
  • Verify subsequent HTTPS requests use the rotated credential value
  • Verify old credential value is no longer injected
• go build ./... passes
• go vet ./... passes
• All egress proxy unit tests pass
• All builds package unit tests pass
• CI must pass

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Note

Medium Risk
Adds a new instance mutation API and runtime egress-proxy rule updates; incorrect validation/rollback could leave proxies injecting stale or inconsistent credentials for running VMs.

Overview
Adds PATCH /instances/{id} to update an instance’s env vars (limited to credential-policy source.env keys) to support live secret/key rotation without restarting the VM.

Implements manager.UpdateInstance with validation, metadata persistence, and egress proxy rule recompilation plus rollback if saving metadata fails; the egress proxy gains UpdateInstanceRules and improved logging/tracing/metrics around register/update/unregister and request handling.

Updates OpenAPI/stainless specs, scopes, and tests (new unit tests and an integration test that rotates a key and verifies the guest still sees mock env while outbound HTTPS uses the rotated value).

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[github-actions]

✱ Stainless preview builds

This PR will update the hypeman SDKs with the following commit message.

feat: support updating egress proxy secret envs for key rotation

✅ hypeman-openapi studio · code

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✅ hypeman-go studio · code

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go get github.com/stainless-sdks/hypeman-go@96b32092d707499c6a962d89a3530b413be4ccab

⚠️ hypeman-typescript studio · code

Your SDK build had at least one "error" diagnostic.
generate ❗ → build ✅ → lint ✅ → test ✅

npm install https://pkg.stainless.com/s/hypeman-typescript/f5bc12b81b0bda445d8feab08f665d1b6438b1f9/dist.tar.gz

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Last updated: 2026-03-20 22:28:40 UTC

[masnwilliams]

solid PR — credential rotation with rollback semantics is well-designed. the integration test proving secrets never leak to the VM is the highlight. main feedback is around histogram bucket config for useful latency data and a minor observability gap in the CONNECT setup path.

[masnwilliams]

lgtm

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