Enable Rails built-in health check endpoint at /up#92
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Mounts Rails::HealthController#show at /up (rails_health_check). Returns 200 when the app boots cleanly, 500 otherwise. The controller responds with an HTML page for browsers/uptime bots and a JSON body for Accept: application/json clients, so load balancers, monitors, and JSON consumers share one endpoint. No custom controller.
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What
Enables Rails' built-in health check endpoint at
/upby mountingRails::HealthController#show:No custom controller. This is the framework's own one-size-fits-all health check, introduced in Rails 7.1.
Why
Uptime monitors, load balancers, and container orchestrators need a stable endpoint to poll. The built-in controller returns
200when the app boots with no exceptions and500otherwise.Behavior
The controller responds to all three request styles we need, from a single route:
Accept: text/html(browser)200, green HTML pageAccept: application/json200,{"status":"up","timestamp":...}Accept/*/*200, HTML pageVerified locally against a booted server (all
200). Nohost_authorizationorallow_browserguard blocks it, and it runs as a standaloneActionController::Base, soprotect_from_forgery/ CSRF does not apply.Notes
Per the Rails docs, this endpoint reflects only that the app booted, not the status of downstream dependencies (DB, S3). That is the intended scope of
rails/health#show; a dependency-aware check would need a custom action, which is deliberately out of scope here.