Oleks
cb369d3be3
Adds a postPatch step that applies metamcp-observability.patch to
the upstream metatool-ai/metamcp v2.4.22 source before pnpm build.
The patch:
* Drops in apps/backend/src/lib/observability/{trace,metrics}.ts:
AsyncLocalStorage trace context + parser/synthesizer per the W3C
contract (Specs/mcp-request-id), plus a hand-rolled
Counter/Histogram so we don't have to touch pnpm-lock.yaml /
pnpmDeps hash (no new npm dependency).
* Wires a top-level express middleware in apps/backend/src/index.ts
that binds trace context, observes mcp_hop_duration_seconds on
response close, and counts mcp_cancellation_total when the
downstream client hangs up mid-response.
* Adds /metrics to the Express app and last-resort process traps
(unhandledRejection / uncaughtException) feeding
mcp_uncaught_throw_total — the smoking-gun signal from
cluster#44.
* Patches process-managed-transport.send() to inject
params._meta.traceparent on every outbound JSON-RPC bound for a
stdio child (MCP _meta convention, Specs/mcp-request-id).
Retire when this lands upstream.
210 lines
7.0 KiB
Nix
210 lines
7.0 KiB
Nix
{
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lib,
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stdenv,
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fetchFromGitHub,
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makeWrapper,
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nodejs_20,
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pnpm_10,
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fetchPnpmDeps,
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pnpmConfigHook,
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postgresql,
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}:
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# MetaMCP — MCP aggregator/orchestrator.
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#
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# Upstream is a pnpm monorepo (Turbo) with two apps:
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# - apps/backend : Express/tRPC API, built with tsup -> dist/index.js
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# port 12009 (internal), runs drizzle-kit migrations at boot
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# - apps/frontend : Next.js 15, port 12008 (public), launched via `next start`
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#
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# Both require runtime node_modules (Next.js non-standalone; drizzle-kit is
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# a devDep invoked at runtime by docker-entrypoint.sh). We ship the whole
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# built tree under $out/lib/metamcp and provide launcher scripts.
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#
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# The upstream Dockerfile patches Next.js' proxy timeout (30s -> 600s) by
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# sed-editing two files inside node_modules/.pnpm/next@.../...; we replicate
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# that in postBuild so the behaviour matches the official image.
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#
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# Build is single-derivation: pnpm fetch -> pnpm build -> install. First
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# build prints the right pnpmDeps hash; paste it back here and rebuild.
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let
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pname = "metamcp";
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version = "2.4.22";
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src = fetchFromGitHub {
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owner = "metatool-ai";
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repo = "metamcp";
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rev = "v${version}";
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hash = "sha256-EEb3RUjsaJ5ZSHSIkAxfdV/BAjZEAvw3rtjALM4RpSc=";
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};
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in
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stdenv.mkDerivation (finalAttrs: {
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inherit pname version src;
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pnpmDeps = fetchPnpmDeps {
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inherit pname version src;
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fetcherVersion = 3;
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hash = "sha256-nHHLLu5wBzzP4i/oTnOkuIiPQvvvBAIIVtKdfpDiXQw=";
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};
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nativeBuildInputs = [
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nodejs_20
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pnpm_10
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pnpmConfigHook
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makeWrapper
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];
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# Upstream pins `packageManager: pnpm@9.0.0`; nixpkgs ships pnpm 10. The
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# lockfile is v9 (forward-compatible). Rewrite the pin to the pnpm we
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# actually have so pnpm 10 doesn't try to network-fetch pnpm@9 and Turbo
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# (which *requires* the field) still finds it.
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postPatch = ''
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${nodejs_20}/bin/node -e '
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const fs = require("fs");
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const pkg = JSON.parse(fs.readFileSync("package.json", "utf8"));
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pkg.packageManager = "pnpm@${pnpm_10.version}";
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if (pkg.engines) delete pkg.engines.pnpm;
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fs.writeFileSync("package.json", JSON.stringify(pkg, null, 2) + "\n");
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'
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# cluster#49, cluster#50 — observability patch: W3C traceparent
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# propagation (HTTP header → params._meta.traceparent on stdio
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# children) + hand-rolled Prometheus metrics on /metrics, no new
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# dependency so pnpmDeps stays untouched. Two new source files
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# under apps/backend/src/lib/observability/ and minimal edits to
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# apps/backend/src/index.ts and process-managed-transport.ts.
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# Retire when this lands upstream.
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patch -p1 < ${./metamcp-observability.patch}
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'';
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# pnpmConfigHook places node_modules; build the workspace with Turbo.
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buildPhase = ''
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runHook preBuild
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# Match the upstream Dockerfile sed-patch on Next.js proxy timeout.
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# Files live under the pnpm virtual store; glob to tolerate minor
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# next/react version bumps on later tags.
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for f in \
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node_modules/.pnpm/next@*/node_modules/next/dist/server/lib/router-utils/proxy-request.js \
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node_modules/.pnpm/next@*/node_modules/next/dist/esm/server/lib/router-utils/proxy-request.js; do
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if [ -f "$f" ]; then
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sed -i -e "s/30000/600000/" "$f"
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fi
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done
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pnpm build
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runHook postBuild
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'';
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installPhase = ''
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runHook preInstall
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mkdir -p $out/lib/metamcp $out/bin
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# Ship the whole built workspace. This is bulky but reliable:
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# `next start` needs .next + node_modules + package.json side-by-side,
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# and the backend's runtime invokes `pnpm exec drizzle-kit migrate`.
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cp -r \
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apps \
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packages \
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node_modules \
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package.json \
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pnpm-workspace.yaml \
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pnpm-lock.yaml \
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turbo.json \
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$out/lib/metamcp/
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# Next.js standalone post-processing: `output: "standalone"` produces
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# apps/frontend/.next/standalone/apps/frontend/server.js but does NOT
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# copy .next/static or public/ into the standalone tree. Do it here
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# so the runtime UI has its CSS, JS chunks and static assets.
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SA=$out/lib/metamcp/apps/frontend/.next/standalone/apps/frontend
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cp -r $out/lib/metamcp/apps/frontend/.next/static $SA/.next/static
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cp -r $out/lib/metamcp/apps/frontend/public $SA/public
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# Launcher: re-implementation of upstream's docker-entrypoint.sh.
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# Cleaner than substituteInPlace-ing the upstream script (the original
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# has overlapping `/app` substrings that break naive replacement) and
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# gives us a single place to keep the orchestration logic in sync.
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cat > $out/bin/metamcp <<EOF
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#!${stdenv.shell}
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set -e
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export PATH=${
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lib.makeBinPath [
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nodejs_20
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pnpm_10
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postgresql # for pg_isready
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]
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}:\$PATH
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ROOT=$out/lib/metamcp
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: "\''${POSTGRES_HOST:=127.0.0.1}"
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: "\''${POSTGRES_PORT:=5432}"
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: "\''${POSTGRES_USER:=postgres}"
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echo "Waiting for PostgreSQL at \$POSTGRES_HOST:\$POSTGRES_PORT..."
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until pg_isready -h "\$POSTGRES_HOST" -p "\$POSTGRES_PORT" -U "\$POSTGRES_USER"; do
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sleep 2
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done
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echo "Running drizzle migrations..."
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cd "\$ROOT/apps/backend"
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pnpm exec drizzle-kit migrate
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echo "Starting backend on :12009..."
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PORT=12009 node "\$ROOT/apps/backend/dist/index.js" &
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BACKEND_PID=\$!
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sleep 3
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kill -0 \$BACKEND_PID 2>/dev/null || { echo "Backend died"; exit 1; }
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echo "Starting frontend on :12008..."
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cd "\$ROOT/apps/frontend/.next/standalone/apps/frontend"
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# Next.js standalone uses \$HOSTNAME as the bind address. The shell
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# inherits HOSTNAME=<system-hostname>, leaving the server unreachable
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# on 127.0.0.1 — force 0.0.0.0 unless overridden via METAMCP_HOSTNAME.
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PORT=12008 HOSTNAME="\''${METAMCP_HOSTNAME:-0.0.0.0}" node server.js &
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FRONTEND_PID=\$!
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sleep 3
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kill -0 \$FRONTEND_PID 2>/dev/null || { kill \$BACKEND_PID 2>/dev/null; echo "Frontend died"; exit 1; }
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trap 'kill \$BACKEND_PID \$FRONTEND_PID 2>/dev/null || true' TERM INT
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wait \$BACKEND_PID \$FRONTEND_PID
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EOF
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chmod +x $out/bin/metamcp
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# Direct sub-launchers (handy for systemd "two-unit" deployments if
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# you ever want to skip the bundled orchestrator).
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makeWrapper ${nodejs_20}/bin/node $out/bin/metamcp-backend \
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--add-flags "$out/lib/metamcp/apps/backend/dist/index.js" \
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--set NODE_ENV production
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cat > $out/bin/metamcp-frontend <<EOF
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#!${stdenv.shell}
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cd $out/lib/metamcp/apps/frontend/.next/standalone/apps/frontend
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exec env HOSTNAME="\''${METAMCP_HOSTNAME:-0.0.0.0}" ${nodejs_20}/bin/node server.js "\$@"
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EOF
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chmod +x $out/bin/metamcp-frontend
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runHook postInstall
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'';
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# The pnpm/turbo build writes into $HOME; give it a writable one.
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preBuild = ''
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export HOME=$TMPDIR
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'';
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meta = {
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description = "MetaMCP — MCP aggregator, orchestrator, middleware, gateway";
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homepage = "https://github.com/metatool-ai/metamcp";
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license = lib.licenses.mit;
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mainProgram = "metamcp";
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platforms = [
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"x86_64-linux"
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"aarch64-linux"
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];
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};
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})
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