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Separate health check endpoint using puma

Puma offers a way to query its internal stats by enabling a controll app in a separate port, this can be useful when we need to know if the app is alive, this is different than normal health check endpoints because it does not get processed by rails at all.

To enable this functionality, all you need to do is to add this line in your puma.rb file:

activate_control_app 'tcp://0.0.0.0:9293', { no_token: true }

It will start a second web server in the port 9293 that can be queried by monitoring tools or even balancer healthcheck.

ecruz@Edwins-MBP % curl 'http://127.0.0.1:9293/stats'
{"started_at":"2021-10-15T21:39:55Z","workers":2,"phase":0,"booted_workers":2,"old_workers":0,"worker_status":[{"started_at":"2021-10-15T21:39:55Z","pid":44969,"index":0,"phase":0,"booted":true,"last_checkin":"2021-10-15T21:40:05Z","last_status":{"backlog":0,"running":5,"pool_capacity":5,"max_threads":5,"requests_count":0}},{"started_at":"2021-10-15T21:39:55Z","pid":44970,"index":1,"phase":0,"booted":true,"last_checkin":"2021-10-15T21:40:05Z","last_status":{"backlog":0,"running":5,"pool_capacity":5,"max_threads":5,"requests_count":0}}]}%
ecruz@Edwins-MBP %

Check the documentation for more options/usages

Learned by Edwin Cruz on Oct 15, 2021

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