Schoolhouse Rock: How a Kibana becomes a build (specifically client-side webpack)

kibana-build-flow.md

• start in Kibana root (shown as "{root}/" throughout below)
• yarn build -> scripts.build -> node scripts/build --all-platforms
• build script requires '{root}/src/dev/build/cli'
  • https://github.com/elastic/kibana/blob/master/src/dev/build/cli.js
• the cli file manages a bunch of initial CLI flags, then calls buildDistributables()
  • https://github.com/elastic/kibana/blob/master/src/dev/build/build_distributables.js#L55
• buildDistributables runs many build tasks, including the OptimizeBuildTask
  • https://github.com/elastic/kibana/blob/master/src/dev/build/build_distributables.js#L120
• the optimize task runs the kibana binary with the optimize flag: {root}/bin/kibana --env.name=production --logging.json=false --optimize
  • https://github.com/elastic/kibana/blob/master/src/dev/build/tasks/optimize_task.js#L35-L43
• the kibana binary checks that you have a node binary in {root}/node/bin/node, then invokes the {root}/src/cli file
  • https://github.com/elastic/kibana/blob/master/bin/kibana
• if there is no "subcommand" (concept from "commander" package, e.g. "bin/kibana something"), it will splice in the "serve" subcommand for you
  • https://github.com/elastic/kibana/blob/master/src/cli/cli.js#L60
• the "commander" package parses the CLI arguments and runs "serve", set up by the serveCommand(program) call
  • https://github.com/elastic/kibana/blob/master/src/cli/cli.js#L36
• serveCommand() sets up the "serve" command
  • https://github.com/elastic/kibana/blob/master/src/cli/serve/serve.js
• "serve" does a lot of configuration and option defaulting and management, then ultimately runs bootstrap()
  • https://github.com/elastic/kibana/blob/master/src/cli/serve/serve.js#L214
• the bootstrap method creates a new "Root" and calls its start method
  • https://github.com/elastic/kibana/blob/master/src/core/server/bootstrap.ts#L73
• the Root object creates a new Server instance and assigns it to this.server, then the Root#start method calls this.server.start
  • https://github.com/elastic/kibana/blob/master/src/core/server/root/index.ts#L48
  • https://github.com/elastic/kibana/blob/master/src/core/server/root/index.ts#L56
• the Server object creates a number of things on instantiation, one being a LegacyCompatModule instance which it assigns to this.legacy
  • https://github.com/elastic/kibana/blob/master/src/core/server/index.ts#L45
  • I believe this LegacyCompatModule is the "old platform"?
  • PluginsModule assigned to this.plugins might be the "new platform"?
• the Server#start method calls this.legacy.service.start()
  • https://github.com/elastic/kibana/blob/master/src/core/server/index.ts#L62
• this.legacy.service is a LegacyService instance
  • https://github.com/elastic/kibana/blob/master/src/core/server/legacy_compat/index.ts#L31
• the LegacyService#start method creates a new kbnServer which requires in the {root}/src/server/kbn_server file
  • https://github.com/elastic/kibana/blob/master/src/core/server/legacy_compat/legacy_service.ts#L75
  • https://github.com/elastic/kibana/blob/master/src/core/server/legacy_compat/legacy_service.ts#L116-L117
  • https://github.com/elastic/kibana/blob/master/src/server/kbn_server.js
• the KbnServer constructor sets up a list of "mixins", or functions that will be called in order -- one is the OptimizeMixin
  • https://github.com/elastic/kibana/blob/master/src/server/kbn_server.js#L100
• mixins are each called with this, this.server, this.config
  • https://github.com/elastic/kibana/blob/master/src/server/kbn_server.js#L127
• the OptimizeMixin handles watch mode etc., and creates a new FsOptimizer
  • https://github.com/elastic/kibana/blob/master/src/optimize/index.js#L62-L67
• FsOptimizer extends from the BaseOptimizer
  • https://github.com/elastic/kibana/blob/master/src/optimize/fs_optimizer.js
• the BaseOptimizer sets up webpack!
  • https://github.com/elastic/kibana/blob/master/src/optimize/base_optimizer.js