Class: AtlasRb::Middleware::RaiseOnReadOnlyMode

Inherits:
Faraday::Middleware
  • Object
show all
Defined in:
lib/atlas_rb/middleware/raise_on_read_only_mode.rb

Overview

Translates Atlas's maintenance-window refusal into a typed Ruby exception.

Atlas refuses every write-shaped action while the repository-wide read-only window is open, answering 503 Service Unavailable with the discriminator error: "read_only_mode" and a Retry-After header. This middleware keys on the status + discriminator pair and raises ReadOnlyModeError.

Why path-independent

Modelled on RaiseOnStaleResource, not RaiseOnResourceError. A maintenance window refuses writes on every path, so a path-keyed rule would have to enumerate the whole write surface and would go stale the moment Atlas grows an endpoint.

Why the discriminator matters

A 503 from a reverse proxy while Atlas restarts carries no JSON body. That is a different condition with a different remedy, and it keeps passing through untouched — only Atlas's own envelope raises.

Instance Method Summary collapse

Instance Method Details

#on_complete(env) ⇒ void

This method returns an undefined value.

Parameters:

  • env (Faraday::Env) —

    the completed response environment.

Raises:



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# File 'lib/atlas_rb/middleware/raise_on_read_only_mode.rb', line 30

def on_complete(env)
  return unless env.status == 503

  body = parse_json(env.body)
  return unless body.is_a?(Hash) && body["error"] == "read_only_mode"

  raise AtlasRb::ReadOnlyModeError.new(
    body["message"],
    code: body["error"],
    retry_after: env.response_headers&.[]("retry-after")&.to_i
  )
end