Malloy Publisher Server

The Malloy Publisher Server is an Express.js server that provides an API for managing and accessing Malloy data models, packages, and queries

Configuration

publisher.config.json lives in this directory. The repository root also contains a symlink (/publisher.config.json → ./packages/server/publisher.config.json) so that running the server from either location picks up the same config. Edit one and you've edited both.

For the BigQuery-enabled variant, see publisher.config.example.bigquery.json and the Quick Start in the repo root README.

Remaining deprecation warnings

Removing the unused trino CLI direct dep (it pulled in @google-cloud/[email protected] → [email protected] → har-validator → hawk → cryptiles) cleaned the worst chain. About 25 npm warn deprecated lines remain on npx @malloy-publisher/server install, all upstream-owned:

• npm CLI tooling: npmlog, gauge, are-we-there-yet, glob@7/8/10, rimraf@3, [email protected], inflight, @npmcli/move-file, node-domexception, querystring — pulled in by npm itself and by node-pre-gyp/node-gyp. Not actionable from this repo.
• [email protected] / [email protected]: surfaced across multiple transitives (Malloy, AWS SDKs, others). Resolves when each upstream bumps to uuid@11.
• [email protected]: pulled in via thrift → @databricks/sql → @malloydata/db-databricks. Resolves when Databricks upgrades @databricks/sql past the thrift dep, or when we replace the Databricks driver.
• [email protected]: listed as a direct dep in packages/server/package.json but not imported anywhere in source — leftover, candidate for removal in a follow-up PR. The actual consumer is @aws-sdk/client-s3 v3.

K6 Test Presets

The Malloy Publisher Server includes several K6 test presets to help you test its performance and stability.

Below is a list of the available test presets:

Smoke Test

Basic functionality test with minimal load.

• File: ./k6-tests/smoke-test.ts
• Virtual Users: 1
• Duration: 1 minute
• 95th Percentile Response Time: < 500ms
• Error Rate: < 1%

Load Test

Testing system under normal load.

• File: ./k6-tests/load-test.ts
• Virtual Users: 50
• Duration: 5 minutes
• 95th Percentile Response Time: < 1s
• Error Rate: < 5%

Stress Test

Testing system under extreme load.

• File:

  ./k6-tests/stress-test.ts

• Virtual Users: 100

• Duration: 10 minutes

• 95th Percentile Response Time: < 2s

• Error Rate: < 10%

Spike Test

Testing system under sudden spikes of load.

• File: ./k6-tests/spike-test.ts
• Stages:
  • 2 minutes ramp-up to 100 users
  • 1 minute at 100 users
  • 2 minutes ramp-down to 0 users
• 95th Percentile Response Time: < 2s
• Error Rate: < 10%

Breakpoint Test

Testing system to find its breaking point.

• File: ./k6-tests/breakpoint-test.ts
• Stages:
  • 2 minutes at 50 users
  • 2 minutes at 100 users
  • 2 minutes at 150 users
  • 2 minutes at 200 users
  • 2 minutes ramp-down to 0 users
• 95th Percentile Response Time: < 3s
• Error Rate: < 15%

Soak Test

Testing system under sustained load.

• File: ./k6-tests/soak-test.ts
• Virtual Users: 10
• Duration: 1 hour
• 95th Percentile Response Time: < 1s
• Error Rate: < 1%

You can run these presets using the K6 testing tool to ensure your system performs well under different load conditions.

For example, this command will run a smoke test against your localhost:

k6 run ./k6-tests/smoke-test.ts --env PUBLISHER_URL=http://::1:4000

OpenTelemetry Integration

The K6 tests can be configured to export metrics to OpenTelemetry collectors using the experimental OpenTelemetry output. This allows you to integrate K6 metrics with your observability stack.

# Build the publisher server
bun run build
# Replace this with an actual OTLP endpoint that you can use
MY_OTLP_ENDPOINT=http://monitoring.myserver.com:4318
# Start an instrumented publisher server
OTEL_EXPORTER_OTLP_ENDPOINT=${MY_OTLP_ENDPOINT} PACKAGE_ROOT=./malloy-samples bun start:instrumented
# Start an instrumented k6 smoke test
K6_OTEL_HTTP_EXPORTER_ENDPOINT=${MY_OTLP_ENDPOINT} K6_OTEL_GRPC_EXPORTER_INSECURE=true K6_OTEL_METRIC_PREFIX=k6_ k6 run ./k6-tests/smoke-test.ts --env PUBLISHER_URL=http://::1:4000

For more information on how to configure OpenTelemetry collectors, please refer to the official documentation: K6 OpenTelemetry Integration

MCP Prompt Capability

Publisher's MCP interface exposes LLM-ready prompts for explaining, generating, translating and summarising Malloy code.

| Prompt ID | Purpose | | ---------------------------------------------- | ----------------------------------------------------------------- | | [email protected] | Explain a Malloy query (sources, transformations, output). | | [email protected] | Create Malloy based on a natural-language goal and model context. | | [email protected] | Convert SQL into Malloy using a model for schema reference. | | [email protected] | Summarise a Malloy model (purpose, entities, joins). |

List prompts:

mcp-client prompts/list

Get a prompt:

mcp-client prompts/get \
  --name [email protected] \
  --arguments '{"query_code":"from flights"}'

These calls return messages ready for your LLM chat completion.