Serverless Introspect

Introspect serverless internals to aid plugin development

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Serverless Introspect

This diagnostic Serverless plugin allows dumping all available serverless commands as well as all the event hooks triggered by each command. This is extremely useful when developing new serverless plugins that rely on properly integrating with existing serverless commands and which need to run at a moment during the execution of such commands.


First, add the plugin to your project:

npm install --save-dev serverless-introspect

Then, inside your project's serverless.yml file add serverless-introspect to the top-level plugins section. If there is no plugin section you will need to add it to the file.

  - serverless-introspect


The plugin adds two commands:

serverless introspect events

This command dumps all available lifecycle events next to a hierarchical tree of the available serverless commands:

$ serverless introspect events
introspect: interactiveCli                   initializeService, setupAws, tabCompletion, end
introspect: config
introspect:   credentials                    config
introspect:   tabcompletion
introspect:     install                      install
introspect:     uninstall                    uninstall
introspect: create                           create
introspect: install                          install
introspect: package                          cleanup, initialize, setupProviderConfiguration, createDeploymentArtifacts, compileLayers, compileFunctions, compileEvents, finalize
introspect:   function*                      package


introspect: introspect!
introspect:   events                         run
introspect:   hooks                          run
introspect: offline                          start
introspect:   start                          init, end
introspect: login                            login
introspect: logout                           logout
introspect: generate-event                   generate-event
introspect: test                             test
introspect: dashboard                        dashboard

In this example, we can see that the offline command has the lifecycle event start. This means that when serverless offline is run, the following events will be fired:

  • before:offline:start
  • offline:start
  • after:offline:start

Similarly, the package command has several lifecycle events, which will cause the following events to fire:

  • before:package:cleanup
  • package:cleanup
  • after:package:cleanup
  • before:package:initialize
  • package:initialize
  • after:package:initialize
  • before:package:setupProviderConfiguration
  • etc...

Commands annotated with * are internal commands that can only be invoked internally by serverless. Commands annotated with ! are container commands that cannot be invoked by themselves.

serverless introspect hooks

This command displays all the plugins hooked up to the available fully qualified events. You may filter the events by providing the command whose lifecycle events should be displayed:

$ sls introspect hooks -c offline
introspect: before:offline:start                                             ServerlessHooks, ServerlessOfflineKinesis
introspect:        offline:start                                             ServerlessOffline
introspect:  after:offline:start                                             ServerlessHooks

This example shows that the ServerlessHooks, ServerlessOfflineKinesis and ServerlessOffline are connected to the various offline command lifecycle events.