Add WorkerProxy assignment, readiness, and state polling APIs by kshyju · Pull Request #12018 · Azure/azure-functions-host

Shyju Krishnankutty (kshyju) · 2026-09-11T18:50:32Z

Summary

Adds single-worker assignment and readiness management to WorkerProxy for compute separation.

Management APIs

Endpoint	Behavior
`GET /admin/worker/ready`	Returns 200 when the worker connection is ready, otherwise 503. Does not require assignment or indicate Host serving readiness.
`PUT /admin/worker/assignment`	Creates an immutable assignment for an already-configured worker: 201 with `Location` on creation, 204 for equivalent live replay. Conflicting assignments and terminal replays return 409 with distinct error codes.
`GET /admin/worker/state`	Omit `lastKnownRevision` for an immediate snapshot. An older revision returns immediately; an equal revision waits up to 60 seconds for a change, returning 204 on timeout.

Implementation details

Integrates readiness with relay attachment, valid worker startup, and termination. Assignment before readiness returns 503 without claiming an identity; assigned-session failure is terminal.
Publishes assignment and state changes atomically, distinguishing creation from replay under the same lock. Equivalent retries preserve revisions; polling cancellation cleans up waiters.
Retains all five assignment fields. Environment settings and the application directory participate in assignment identity only; the proxy does not apply configuration or initiate worker initialization.
Adds injectable capability finalization while preserving existing HTTP capability rewriting.
Uses management-listener-only routes, source-generated JSON serialization, and required WorkerProxy:PodName configuration.
Matches the Host link endpoint's validation envelope, returning all detected field errors together. Explicit assignment JSON parsing and charset validation preserve the 400 InvalidBody envelope for malformed bodies, incompatible types, and unsupported content types or charsets.
Preserves stable assignment error codes: WorkerNotReady (503), WorkerTerminated (409), and AssignmentConflict (409). A conflicting identity takes precedence over terminal replay.
Validates lastKnownRevision as an optional, single nonnegative int64 query value no greater than the current revision. Invalid values return 400; explicit zero participates in normal polling.
Sends Cache-Control: no-store on readiness and state responses, including errors and polling timeouts. Replaces the earlier POST routes rather than retaining aliases.

Includes unit and integration coverage for concurrent assignment creation/replay, conflicts, relay lifecycle, polling/query validation, serialization, cache headers, and listener isolation.

Issue describing the changes in this PR

Resolves #11974.

Pull request checklist

IMPORTANT: Currently, changes must be backported to the in-proc branch to be included in Core Tools and non-Flex deployments.

Backporting to the in-proc branch is not required; otherwise, link the backport PR.
My changes do not require documentation changes; otherwise, link the documentation issue.
My changes should not be added to the release notes; otherwise, add notes to release_notes.md.
My changes do not need to be backported to a previous version; otherwise, link the tracking issue/PR.
My changes do not require diagnostic events changes; otherwise, update the events and related documentation.
I have added all required tests (unit tests, E2E tests).

Additional information

The HTTP contract follows the resource-oriented proposal in serverless-paas-balam/FlexConsumption-BYOC#242. Platform contract agreement remains tracked by #11971; these changes do not imply platform sign-off or production-security approval.

Add immutable assignment state, revision polling, relay lifecycle readiness, and injectable capability finalization. Expose management-only readiness, assignment, and instance-state endpoints with Host-aligned validation errors and source-generated JSON serialization. Includes state, relay, serialization, and endpoint integration coverage for #11974. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

🟡 Changes recommended

The required pod name is absent from the checked-in development launch profile, causing normal local startup to fail.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds WorkerProxy lifecycle management for compute-separated workers, implementing #11974.

Changes:

Adds immutable assignment/readiness state with revision-based polling.
Adds management-only readiness, assignment, and instance-state APIs.
Integrates validated StartStream handling and injectable capability finalization with extensive tests.

File summaries

File	Description
`test/Functions.WorkerProxy.Tests/WorkerProxyWebApplicationFactory.cs`	Adds test pod identity.
`test/Functions.WorkerProxy.Tests/WorkerProxyOptionsTests.cs`	Tests pod-name binding.
`test/Functions.WorkerProxy.Tests/WorkerProxyEnvironmentConfigurationTests.cs`	Tests environment pod identity.
`test/Functions.WorkerProxy.Tests/WorkerProxyApplicationTests.cs`	Tests service registration and validation.
`test/Functions.WorkerProxy.Tests/State/WorkerPodStateManagerTests.Polling.cs`	Tests polling and races.
`test/Functions.WorkerProxy.Tests/State/WorkerPodStateManagerTests.cs`	Tests state transitions and concurrency.
`test/Functions.WorkerProxy.Tests/State/WorkerAssignmentTests.cs`	Tests assignment validation and equality.
`test/Functions.WorkerProxy.Tests/Rpc/FunctionRpcRelayTests.Readiness.cs`	Tests relay-driven readiness.
`test/Functions.WorkerProxy.Tests/Rpc/FunctionRpcRelayTests.Management.cs`	Tests end-to-end management behavior.
`test/Functions.WorkerProxy.Tests/Rpc/FunctionRpcRelayTests.HttpCapabilities.cs`	Updates HTTP capability scenarios.
`test/Functions.WorkerProxy.Tests/Rpc/FunctionRpcRelayTests.cs`	Updates relay fixtures for `StartStream`.
`test/Functions.WorkerProxy.Tests/Rpc/FunctionRpcRelayTests.CapabilityFinalization.cs`	Tests injectable capability finalization.
`test/Functions.WorkerProxy.Tests/Management/WorkerProxyJsonContextTests.cs`	Tests generated JSON contracts.
`test/Functions.WorkerProxy.Tests/Management/ManagementApiHandlersTests.cs`	Tests handler validation and outcomes.
`test/Functions.WorkerProxy.Tests/Management/ManagementApiEndpointTests.cs`	Tests routes and listener isolation.
`test/Functions.WorkerProxy.Tests/Http/WorkerEndpointReadinessProbeOptionsTests.cs`	Supplies required test identity.
`src/Functions.WorkerProxy/WorkerProxyOptionsValidator.cs`	Validates pod identity.
`src/Functions.WorkerProxy/WorkerProxyOptions.cs`	Adds required pod-name option.
`src/Functions.WorkerProxy/WorkerProxyApplication.cs`	Registers state and management services.
`src/Functions.WorkerProxy/State/WorkerStatePollResult.cs`	Models polling outcomes.
`src/Functions.WorkerProxy/State/WorkerPodStatus.cs`	Defines published pod status.
`src/Functions.WorkerProxy/State/WorkerPodStateManager.cs`	Implements lifecycle and polling state.
`src/Functions.WorkerProxy/State/WorkerPodState.cs`	Defines immutable state snapshots.
`src/Functions.WorkerProxy/State/WorkerAssignmentState.cs`	Defines assignment lifecycle states.
`src/Functions.WorkerProxy/State/WorkerAssignmentResult.cs`	Defines assignment outcomes.
`src/Functions.WorkerProxy/State/WorkerAssignment.cs`	Captures immutable assignment identity.
`src/Functions.WorkerProxy/Rpc/IWorkerCapabilityFinalizer.cs`	Introduces capability-finalization abstraction.
`src/Functions.WorkerProxy/Rpc/FunctionRpcRelay.Session.cs`	Integrates readiness and finalization.
`src/Functions.WorkerProxy/Rpc/FunctionRpcRelay.cs`	Injects state and finalizer dependencies.
`src/Functions.WorkerProxy/Management/WorkerProxyJsonContext.cs`	Adds source-generated JSON metadata.
`src/Functions.WorkerProxy/Management/WorkerPodStateResponse.cs`	Defines public pod-state payload.
`src/Functions.WorkerProxy/Management/WorkerInstanceState.cs`	Defines instance-state response.
`src/Functions.WorkerProxy/Management/WorkerAssignRequest.cs`	Defines assignment request payload.
`src/Functions.WorkerProxy/Management/WorkerApiErrorResponse.cs`	Defines lifecycle error envelope.
`src/Functions.WorkerProxy/Management/WorkerApiErrorCodes.cs`	Defines stable error codes.
`src/Functions.WorkerProxy/Management/WorkerApiError.cs`	Defines API error details.
`src/Functions.WorkerProxy/Management/RequestValidationResponse.cs`	Defines validation response envelope.
`src/Functions.WorkerProxy/Management/RequestValidationError.cs`	Defines field validation errors.
`src/Functions.WorkerProxy/Management/ManagementApiHandlers.cs`	Implements management API behavior.
`src/Functions.WorkerProxy/Management/ManagementApiEndpoints.cs`	Maps management-only routes.
`src/Functions.WorkerProxy/Management/InstanceStatePollRequest.cs`	Defines polling requests.
`src/Functions.WorkerProxy/Http/WorkerHttpCapabilityProvider.cs`	Implements the finalizer abstraction.

Review details

Suppressed comments (4)

test/Functions.WorkerProxy.Tests/State/WorkerAssignmentTests.cs:54

Use explicit ordinal string comparisons for each field selector instead of ==.
test/Functions.WorkerProxy.Tests/State/WorkerPodStateManagerTests.Polling.cs:76
Use string.Equals with an explicit ordinal comparison for this transition selector.
test/Functions.WorkerProxy.Tests/Management/ManagementApiHandlersTests.cs:393
Use string.Equals with an explicit ordinal comparison for this transition selector.

        if (transition == "terminate")

test/Functions.WorkerProxy.Tests/Management/ManagementApiEndpointTests.cs:194

Use an explicit ordinal comparison when deciding whether to attach a request body.

            Content = method == "POST" ? JsonBody("{}") : null

Files reviewed: 42/42 changed files
Comments generated: 7
Review effort level: Balanced

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Supply a development pod name in the launch profile and use explicit ordinal string comparisons in the affected tests. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Pump the captured test synchronization context until the delayed inbound continuation finishes before asserting replacement readiness. Preserve nonblocking production termination behavior. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

🔵 Needs a closer look

The concurrency-sensitive lifecycle state machine and platform-facing management contract warrant final human validation.

Review details

Files reviewed: 43/43 changed files
Comments generated: 0 new
Review effort level: Balanced

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

🟡 Changes recommended

Assignment requests with an unknown JSON charset currently return 500 instead of the documented 400 validation envelope.

Get a fresh assessment by requesting another Copilot review.

Review details

Files reviewed: 42/42 changed files
Comments generated: 1
Review effort level: Balanced

…rtions Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot

🟡 Changes recommended

The new routes conflict with the linked, still-open platform contract and acceptance criteria.

Get a fresh assessment by requesting another Copilot review.

Review details

Files reviewed: 42/42 changed files
Comments generated: 1
Review effort level: Balanced

Copilot

🔵 Needs a closer look

The cross-component wire contract remains gated by unresolved platform agreement in #11971.

Review details

Files reviewed: 42/42 changed files
Comments generated: 1
Review effort level: Balanced

+namespace Azure.Functions.WorkerProxy.Management;
+
+/// <summary>
+/// Wraps validation and lifecycle failures in the same management API error envelope.


Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Shyju Krishnankutty (kshyju) requested a balanced review from Copilot September 11, 2026 18:50

Copilot started reviewing on behalf of Shyju Krishnankutty (kshyju) September 11, 2026 18:51 View session

Shyju Krishnankutty (kshyju) requested a review from Brett Samblanet (brettsam) September 11, 2026 18:52

Copilot AI reviewed Sep 11, 2026

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Shyju Krishnankutty (kshyju) and others added 2 commits September 11, 2026 12:17

Fix WorkerProxy development startup and review feedback

74b3e37

Supply a development pod name in the launch profile and use explicit ordinal string comparisons in the affected tests. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Shyju Krishnankutty (kshyju) requested a balanced review from Copilot September 11, 2026 19:56

Copilot started reviewing on behalf of Shyju Krishnankutty (kshyju) September 11, 2026 19:57 View session

Copilot AI reviewed Sep 11, 2026

View reviewed changes

Document explicit management API JSON parsing rationale

04f70cd

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Shyju Krishnankutty (kshyju) marked this pull request as ready for review September 11, 2026 20:33

Shyju Krishnankutty (kshyju) requested a review from a team as a code owner September 11, 2026 20:33

Align WorkerProxy management APIs with resource-oriented contract

49e6d5c

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Shyju Krishnankutty (kshyju) marked this pull request as draft September 11, 2026 22:56

Shyju Krishnankutty (kshyju) requested a balanced review from Copilot September 11, 2026 22:56

Copilot started reviewing on behalf of Shyju Krishnankutty (kshyju) September 11, 2026 22:57 View session

Copilot AI reviewed Sep 11, 2026

View reviewed changes

Comment thread src/Functions.WorkerProxy/Management/ManagementApiEndpoints.cs

Fix assignment charset validation and synchronize timer disposal asse…

1141b17

…rtions Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Shyju Krishnankutty (kshyju) requested a balanced review from Copilot September 11, 2026 23:34

Copilot started reviewing on behalf of Shyju Krishnankutty (kshyju) September 11, 2026 23:35 View session

Copilot AI reviewed Sep 11, 2026

View reviewed changes

Comment thread src/Functions.WorkerProxy/Management/ManagementApiEndpoints.cs

Shyju Krishnankutty (kshyju) requested a balanced review from Copilot September 11, 2026 23:43

Copilot started reviewing on behalf of Shyju Krishnankutty (kshyju) September 11, 2026 23:44 View session

Shyju Krishnankutty (kshyju) marked this pull request as ready for review September 11, 2026 23:48

Copilot AI reviewed Sep 11, 2026

View reviewed changes

Comment thread src/Functions.WorkerProxy/Management/WorkerApiErrorResponse.cs

namespace Azure.Functions.WorkerProxy.Management;

/// <summary>

/// Wraps validation and lifecycle failures in the same management API error envelope.

Shyju Krishnankutty (kshyju) and others added 2 commits September 11, 2026 19:52

Make relay shutdown test logging gates deterministic

67a85fc

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Supply pod identity to WorkerProxy CI smoke container

fa48ddb

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

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Add WorkerProxy assignment, readiness, and state polling APIs - #12018

Add WorkerProxy assignment, readiness, and state polling APIs#12018
Shyju Krishnankutty (kshyju) wants to merge 8 commits into
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Shyju Krishnankutty (kshyju) commented Sep 11, 2026 •

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Shyju Krishnankutty (kshyju) commented Sep 11, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Management APIs

Implementation details

Issue describing the changes in this PR

Pull request checklist

Additional information

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🟡 Changes recommended

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Shyju Krishnankutty (kshyju) commented Sep 11, 2026 •

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