Server: Hooks

Hooks, unlike interceptors, are executed outside of the request chain, such as when a server starts or stops. They run in FIFO order sequentially and do not wrap one another. They can be used to provide custom boot sequences, external instrumentation support, or shutdown alerting.

You can create a hook by extending the Gruf::Hooks::Base class and defining the methods on the hook you wish to implement:

class MyHook < Gruf::Hooks::Base
  def before_server_start(server:)
    # do my thing before the server starts  
  end
  
  def after_server_stop(server:)
    # do my thing after the server stops
  end
end

# Then in an initializer:

Gruf.configure do |c|
  c.hooks.use(MyHook, option_foo: 'value 123')
end

Exceptions raised in hooks will halt the execution chain and bubble up the stack appropriately.

Available Hook Insertion Points

Current hook insertion points are:

• before_server_start - Right before the gRPC server starts
• after_server_stop - Right after the gRPC server is shutdown

Note that exceptions raised in before_server_start will halt the execution chain for the remaining before_server_start hooks, but will still execute the after_server_stop hooks as expected. Exceptions raised in after_server_stop will prevent further after_server_stop hooks from running.

Note: Hooks are available in Gruf 2.7+ or later only.

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