Expose WEB_CONCURRENCY in compose / ENV

[jmthomas]

The WEB_CONCURRENCY value for the cmd-tlm-api is important to set to help COSMOS scale. It should typically be set to the number of cores on your machine. The default is 4 which is probably too low. The script-runner-api default is 2 which might also be a little low but matters much less than the cmd-tlm-api.

[crawlchat]

Thanks for raising this! This is a great performance tip. Here's the relevant context and how to configure it:

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📖 WEB_CONCURRENCY Details

The WEB_CONCURRENCY variable controls the number of Puma worker processes (forked web server processes) for the Rails APIs. It's configured in:

• cmd-tlm-api: defaults to 4
• script-runner-api: defaults to 2

workers ENV.fetch("WEB_CONCURRENCY") { 4 }  # cmd-tlm-api
workers ENV.fetch("WEB_CONCURRENCY") { 2 }  # script-runner-api

The cmd-tlm-api is the critical one — it handles all command and telemetry REST API requests, so it benefits most from higher concurrency.

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✅ How to Configure

Add WEB_CONCURRENCY to your .env file (in the cosmos-project) or set it per-service in your compose.yaml environment section:

# In compose.yaml
openc3-cmd-tlm-api:
  environment:
    - WEB_CONCURRENCY=8  # Set to number of cores on your machine

Or in your .env:

WEB_CONCURRENCY=8

Tip: The current .env does not include WEB_CONCURRENCY by default , so you'll need to add it manually. Set it to the number of CPU cores on your host machine for best results.

This is especially impactful for cmd-tlm-api under heavier workloads.