feat(fast-time): rmcp /mcp transport + legacy SSE shim by lucarlig · Pull Request #5299 · IBM/mcp-context-forge

lucarlig · 2026-06-18T09:00:00Z

✨ Feature / Enhancement PR

🔗 Epic / Issue

Not linked.

🚀 Summary (1-2 sentences)

Move the Rust fast-time server to the rmcp-backed Streamable HTTP implementation while preserving the legacy SSE and Go-compatible REST surfaces. Wire compose to the Rust server and add a GHCR publisher for ghcr.io/ibm/fast-time-server.

📏 Reviewability

This PR has one clear purpose
The linked issue is not labeled triage (no linked issue)
Unrelated bugs or improvements are tracked in separate issues/PRs
Tests are included with the code they validate

🧪 Checks

Rust fast-time server

cargo fmt -p fast-time-server --check
cargo test -p fast-time-server
cargo clippy -p fast-time-server --all-targets -- -D warnings
cargo build -p fast-time-server
Runtime host allowlist smoke: allowed host returns 200; unlisted host returns 403
Built-container dual-mode smoke: /health, /version, REST timezone lookup, Streamable HTTP initialize, and legacy SSE response
Built-container SSE-only smoke with generated performance-compose arguments

Workflows and repo hygiene

actionlint .github/workflows/fast-time-server-image.yml
actionlint .github/workflows/wrapper.yml .github/workflows/sql-sanitizer.yml .github/workflows/fast-time-server-image.yml
make detect-secrets-scan
make pre-commit
git diff --check
Fast-time reference sweep: active runtime, CI, and docs entrypoints now point to Rust; remaining Go references are legacy Go source/docs

Compose and deployment surfaces

SQL sanitizer startup smoke: Rust fast-time starts on :9080; /health and /version return 200
Small local make testing-up compose smoke with constrained gateway resources; verified gateway, fast-time, auth, and registration paths; make testing-down completed
Performance compose generator smoke: generated /tmp/docker-compose.perf.yml from tests/performance/config.yaml; docker compose config --quiet passed
docker compose -f docker-compose.yml config --quiet
docker compose -f docker-compose-verbose-logging.yml config --quiet
docker compose -f docker-compose-debug.yml config --quiet
docker compose -f docker-compose-performance.yml config --quiet
helm template mcp-stack charts/mcp-stack
Compose service builds for fast_time_server, slow_time_server, and benchmark_server in main, debug, verbose-logging, and performance compose files

Rust server container images

All changed Rust server image definitions build on native linux/arm64
All changed Rust server image definitions cross-build for linux/amd64
Built images run as non-root mcpuser and include ca-certificates plus curl
A2A echo container smoke: /health, agent card, and JSON-RPC SendMessage
Benchmark container smoke for both Dockerfile and Containerfile: /health and tools/list
Fast-time container smoke for both Dockerfile and Containerfile: /health, /version, REST timezone lookup, and Streamable HTTP initialize
Slow-time container smoke: /health and tools/list
Makefile container helpers build successfully for benchmark, slow-time, and fast-time

Full-suite status

make lint (not run; scoped lint/checks above ran instead)
make test (not run; scoped tests above ran instead)
CHANGELOG updated (not user-facing)

📓 Notes (optional)

The legacy /sse, /messages, and /message paths stay as a hand-rolled compatibility shim because rmcp Streamable HTTP does not reproduce the existing ContextForge SSE endpoint semantics.
fast_time_server in compose defaults to the published GHCR image and still supports local overrides with FAST_TIME_IMAGE.
Streamable HTTP Host validation is configurable through MCP_ALLOWED_HOSTS / -allowed-hosts, with compose defaults and -public-url host support.
sql-sanitizer E2E now starts the Rust fast-time server on :9080, matching the workflow's existing health probes and gateway registration URL.
Wrapper E2E and generated performance compose now build/start the Rust fast-time server instead of the Go implementation.
Verbose/debug/performance compose variants and Helm values now describe/use the Rust fast-time server consistently with the main compose path.

ja8zyjits

LGTM
only changes to an mcp-server low impact on core CF.

waiting for confirmation

Signed-off-by: lucarlig <luca.carlig@ibm.com>

- Echo the client's requested protocolVersion when supported, else the latest version this server speaks (both SSE and streamable HTTP). - Track last-seen time per streamable-HTTP session and evict idle ones past SESSION_IDLE_TTL instead of leaking until the cap is reached. - get_stats now counts its own invocation like every other tool, and the unreachable session-id header fallback is dropped. Signed-off-by: lucarlig <luca.carlig@ibm.com>

…ools Replace the hand-rolled MCP layer with the official Rust SDK (rmcp): - /mcp Streamable HTTP transport is now served by rmcp's StreamableHttpService + LocalSessionManager, removing the bespoke session map and JSON-RPC dispatch (streamable_http.rs). A lightweight gate caps concurrent sessions at MAX_ACTIVE_SESSIONS (rmcp's session manager has no built-in cap); existing sessions are cleaned up by rmcp on disconnect/DELETE. - Tools are declared once via #[tool] macros with schemas derived from their parameter types, removing the hand-written tool schemas and dispatch (mcp.rs). The schema_error/schema_success fixtures retain their declared outputSchema. - The legacy HTTP+SSE transport remains a hand-rolled shim (documented exception) because rmcp does not reproduce the bespoke ContextForge legacy-SSE semantics (endpoint event, sessionId/session_id aliases, 202/404/410 codes). It delegates tools/list and tools/call back to the rmcp server so schemas and logic never drift. - serverInfo is built explicitly so /mcp reports the server identity rather than rmcp's own crate name. Behavior parity (DST conversion, echo delay limit, protocol-version echo, output schemas) is covered by unit tests; both transports verified end-to-end. Signed-off-by: lucarlig <luca.carlig@ibm.com>

Port the Go fast-time-server's resource and prompt surface to the Rust server so it advertises the same MCP capabilities: - 4 resources: timezone://info, time://current/world, time://formats, time://business-hours. - 3 prompts: compare_timezones, schedule_meeting, convert_time_detailed. - Advertise resources + prompts capabilities; add readOnly / idempotent / title annotations to get_system_time and convert_time. Resources and prompts are shared by both the /mcp transport (rmcp ServerHandler) and the legacy SSE shim (resources/list, resources/read, prompts/list, prompts/get). Signed-off-by: lucarlig <luca.carlig@ibm.com>

Bring the Rust server up to the Go transport/CLI surface: - clap CLI: --transport (stdio|sse|http|dual|rest), --addr/--listen/--port, --public-url, --auth-token, --log-level. With no arguments it still serves every HTTP route on BIND_ADDRESS (default 0.0.0.0:9080), preserving the container/Makefile behavior; the HTTP modes all serve the full router. - stdio transport via rmcp serve(), for `--transport stdio`. - Bearer-token auth middleware for the HTTP transports, exempting /health and /version, mirroring the Go authMiddleware (401 + WWW-Authenticate). - Send tracing logs to stderr so the stdio transport keeps stdout as a pure JSON-RPC stream. Signed-off-by: lucarlig <luca.carlig@ibm.com>

Port the Go fast-time-server's REST API to the Rust server, alongside the existing high-throughput /api/echo and /api/time benchmark endpoints: - /api/v1/time (+ /{tz}), /api/v1/convert, /api/v1/convert/batch - /api/v1/timezones (+ /{tz}), /api/v1/resources (+ /{slug}), /api/v1/prompts (+ /{name}/execute) - /api/v1/test/echo, /api/v1/test/validate, /api/v1/test/performance - permissive CORS with a 204 preflight, applied as the outermost layer The REST resources/prompts mirror the Go REST handlers' simpler payloads, which differ from the richer MCP resource/prompt content. Signed-off-by: lucarlig <luca.carlig@ibm.com>

Serve /api/v1/openapi.json (an OpenAPI 3.0 document describing the REST surface) and /api/v1/docs (a Swagger UI page), matching the Go server. Signed-off-by: lucarlig <luca.carlig@ibm.com>

Signed-off-by: lucarlig <luca.carlig@ibm.com>

ja8zyjits

this and the sql-sanitizer.yaml changes.
Iam not sure if that is needed here?

ja8zyjits

LGTM

Signed-off-by: lucarlig <luca.carlig@ibm.com>

Lang-Akshay

LGTM

lucarlig requested review from Lang-Akshay, brian-hussey, crivetimihai, ja8zyjits and msureshkumar88 as code owners June 18, 2026 09:00

lucarlig self-assigned this Jun 18, 2026

lucarlig force-pushed the user/luca/rust-fast-time-sse branch 4 times, most recently from fa8d028 to 1d5babc Compare June 25, 2026 10:58

lucarlig force-pushed the user/luca/rust-fast-time-sse branch from 1d5babc to 5b32e6a Compare June 26, 2026 09:02

lucarlig changed the title ~~feat: add Rust fast-time SSE transport~~ feat(fast-time): rmcp /mcp transport + legacy SSE shim Jun 26, 2026

jonpspri added the MUST P1: Non-negotiable, critical requirements without which the product is non-functional or unsafe label Jun 26, 2026

ja8zyjits previously approved these changes Jun 26, 2026

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ja8zyjits self-assigned this Jun 26, 2026

ja8zyjits added the do-not-merge Do NOT merge. This requires manual effort, with multiple checks! label Jun 26, 2026

lucarlig force-pushed the user/luca/rust-fast-time-sse branch 4 times, most recently from d3ff2cf to 0760b2f Compare June 26, 2026 16:24

lucarlig removed the do-not-merge Do NOT merge. This requires manual effort, with multiple checks! label Jun 29, 2026

lucarlig mentioned this pull request Jun 29, 2026

chore: migrate Rust server runtime images from debian:trixie-slim to ubi-minimal #5404

Merged

12 tasks

lucarlig added 7 commits June 29, 2026 10:23

feat: add rust fast-time sse transport

cf12142

Signed-off-by: lucarlig <luca.carlig@ibm.com>

refactor: split rust fast-time transports

dba65e8

Signed-off-by: lucarlig <luca.carlig@ibm.com>

lucarlig added 7 commits June 29, 2026 10:23

feat(fast-time): add OpenAPI spec and Swagger docs endpoints

7b2421f

Serve /api/v1/openapi.json (an OpenAPI 3.0 document describing the REST surface) and /api/v1/docs (a Swagger UI page), matching the Go server. Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: restore fast-time Rust CI parity

97a9df3

Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: publish Rust fast-time server image

dcde84b

Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: stabilize fast-time CI

8e1b364

Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: use Rust fast-time in wrapper paths

4cfbe28

Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: align fast-time references with Rust server

2f7362c

Signed-off-by: lucarlig <luca.carlig@ibm.com>

fix: build Rust server container images

9499be9

Signed-off-by: lucarlig <luca.carlig@ibm.com>

lucarlig force-pushed the user/luca/rust-fast-time-sse branch from 17c9920 to 9499be9 Compare June 29, 2026 10:04

ja8zyjits requested changes Jun 29, 2026

View reviewed changes

Comment thread docker-compose.yml

ja8zyjits previously approved these changes Jun 29, 2026

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fix: disable gunicorn control socket in read-only containers

74cc7bd

Signed-off-by: lucarlig <luca.carlig@ibm.com>

lucarlig dismissed ja8zyjits’s stale review via 74cc7bd June 29, 2026 13:54

lucarlig force-pushed the user/luca/rust-fast-time-sse branch from 9911180 to 74cc7bd Compare June 29, 2026 14:51

Lang-Akshay approved these changes Jun 29, 2026

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Lang-Akshay added this pull request to the merge queue Jun 29, 2026

Merged via the queue into main with commit 1b98aeb Jun 29, 2026
76 of 77 checks passed

Lang-Akshay deleted the user/luca/rust-fast-time-sse branch June 29, 2026 15:37

lucarlig mentioned this pull request Jun 29, 2026

[BUG]: Stabilize flaky Vitest timeout in token details modal test #5424

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feat(fast-time): rmcp /mcp transport + legacy SSE shim#5299

feat(fast-time): rmcp /mcp transport + legacy SSE shim#5299
Lang-Akshay merged 15 commits into
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lucarlig commented Jun 18, 2026 •

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lucarlig commented Jun 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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✨ Feature / Enhancement PR

🔗 Epic / Issue

🚀 Summary (1-2 sentences)

📏 Reviewability

🧪 Checks

Rust fast-time server

Workflows and repo hygiene

Compose and deployment surfaces

Rust server container images

Full-suite status

📓 Notes (optional)

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lucarlig commented Jun 18, 2026 •

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