Gatsby bootstrap lifecycle

Gatsby-bootstrap-lifecycle.md

Sequence of Gatsby's bootstrap lifecycle with links to source code as of v2.0.0

permalink https://github.com/gatsbyjs/gatsby/blob/ffd8b2d691c995c760fe380769852bcdb26a2278/packages/gatsby/src/bootstrap/index.js

1. open and validate gatsby-config (get-config-file.js) 1.5 load themes (swyx added this note July 2019)
2. load plugins (load-plugins/index.js) from the list given in gatsby-config.js
3. onPreBootstrap: runs onPreBootstrap if it is implemented in any plugins, for example gatsby-plugin-typography. Receives handy apiCallArgs and pluginOptions.
4. delete html and css files from previous builds (from the /public directory) - a simple delete
5. delete /.cache if hash of package.json, gatsby-config.js, gatsby-node.js, and plugin versions has changed. then init or reuse /.cache/cache.
6. copy gatsby files from the cache-dir folder in the main gatsby package into your new /.cache. Make sure ./cache/json exists and ./cache/fragments is empty. If your plugins implement gatsby-browser and gatsby-ssr, write them out to .cache/api-runner-browser-plugins.js and .cache/api-runner-ssr.js.
7. source and transform nodes: run sourceNodes if implemented by plugins (eg gatsby-source-wikipedia), then garbage collect stale nodes

• onCreateNode runs whenever the createNode action is called (which dispatches CREATE_NODE)

8. building schema: runs schema/index.js to build everything involved in the RootQueryType GraphQLSchema. a lot of code here i'm skipping over.
9. add extensions: by default gatsby handles .js and .jsx, but plugins can implement resolvableExtensions to add filetypes for other languages, eg gatsby-plugin-typescript
10. createPages: run createPages hooks implemented by your plugins (e.g. page-hot-reloader) and your gatsby-node.js

• onCreatePage runs whenever the createPage action is called (which dispatches CREATE_PAGE)

11. createPagesStatefully: "A variant on createPages for plugins that want to have full control over adding/removing pages." more here.
12. onPreExtractQueries: runs the onPreExtractQueries hook for plugins like gatsby-transformer-sharp and gatsby-source-contentful.
13. update schema: run schema AGAIN! (why? the comment says "Update Schema for SitePage."). Report conflicting field types.
14. extract queries from components: starting from query-watcher.js, use queryCompiler to either replaceComponentQuery for pages or replaceStaticQuery for staticQueries.
15. (if not in NODE_ENV != production) start the createPages page-hot-reloader
16. run graphql queries: runQueriesForPathnames for pageQueries and staticQueries.
17. write out page data: writePages!
18. write out redirect data: writes out browser redirects to .cache/redirects.json
19. bootstrap finished - ${process.uptime()}s: yay
20. onPostBootstrap: calls "onPostBootstrap" hook, but no packages seem to implement it.