feat(build): conditional page builds are no longer experimental (they…

… are default)

.circleci/config.yml

@@ -258,15 +258,6 @@ jobs:
       - e2e-test:
           test_path: integration-tests/artifacts
 
-  # temporary
-  integration_tests_artifacts_conditional_page_builds:
-    executor: node
-    steps:
-      - e2e-test:
-          test_path: integration-tests/artifacts
-    environment:
-      GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES: 1
-
   integration_tests_ssr:
     executor: node
     steps:
@@ -606,8 +597,6 @@ workflows:
           <<: *e2e-test-workflow
       - integration_tests_artifacts:
           <<: *e2e-test-workflow
-      - integration_tests_artifacts_conditional_page_builds:
-          <<: *e2e-test-workflow
       - integration_tests_ssr:
           <<: *e2e-test-workflow
       - integration_tests_images:

docs/docs/conceptual/overview-of-the-gatsby-build-process.md

@@ -304,7 +304,7 @@ Page queries that were queued up earlier from query extraction are run so the da
 
 With everything ready for the HTML pages in place, HTML is compiled and written out to files so it can be served up statically. Since HTML is being produced in a Node.js server context, [references to browser APIs like `window` can break the build](/docs/debugging-html-builds/) and must be conditionally applied.
 
-By default, Gatsby rebuilds static HTML for all pages on each build. There is an experimental feature flag `GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES` which enables [conditional page builds](/docs/conditional-page-builds/).
+Gatsby will smartly rebuild only needed HTML files. This might mean 0 html files being generated if nothing that was used for html files changed, some part of pages in case if data that is used changed or all files in case of code change.
 
 ## What do you get from a successful build?
 

integration-tests/artifacts/__tests__/index.js

@@ -463,13 +463,11 @@ describe(`Second run (different pages created, data changed)`, () => {
       })
     })
 
-    if (process.env.GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES) {
-      it(`should recreate only some html files`, () => {
-        expect(manifest[runNumber].generated.sort()).toEqual(
-          expectedPagesToBeGenerated.sort()
-        )
-      })
-    }
+    it(`should recreate only some html files`, () => {
+      expect(manifest[runNumber].generated.sort()).toEqual(
+        expectedPagesToBeGenerated.sort()
+      )
+    })
   })
 
   describe(`page-data files`, () => {

packages/gatsby-cli/src/create-cli.ts

@@ -243,18 +243,20 @@ function buildLocalCommands(cli: yargs.Argv, isLocalSite: boolean): void {
           type: `string`,
           describe: `Tracer configuration file (OpenTracing compatible). See https://gatsby.dev/tracing`,
         })
-        // log-pages and write-to-file are specific to experimental GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES feature
-        // because of that they are hidden from `--help` but still defined so `yargs` know about them
+        // log-pages and write-to-file were added specifically to experimental GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES feature
+        // in gatsby@2. They are useful, but not very applicable (specifically `--write-to-file`) as generic approach, as it only
+        // list pages without other artifacts, so it's useful in very narrow scope. Because we don't have alternative right now
+        // those toggles are kept for users that rely on them, but we won't promote them and will keep them "hidden".
         .option(`log-pages`, {
           type: `boolean`,
           default: false,
-          describe: `Log the pages that changes since last build (only available when using GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES).`,
+          describe: `Log the pages that changes since last build.`,
           hidden: true,
         })
         .option(`write-to-file`, {
           type: `boolean`,
           default: false,
-          describe: `Save the log of changed pages for future comparison (only available when using GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES).`,
+          describe: `Save the log of changed pages for future comparison.`,
           hidden: true,
         }),
     handler: handlerP(

packages/gatsby/src/commands/build-html.ts

@@ -271,13 +271,9 @@ export async function buildHTMLPagesAndDeleteStaleArtifacts({
 }> {
   buildUtils.markHtmlDirtyIfResultOfUsedStaticQueryChanged()
 
-  const { toRegenerate, toDelete } = process.env
-    .GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES
-    ? buildUtils.calcDirtyHtmlFiles(store.getState())
-    : {
-        toRegenerate: [...store.getState().pages.keys()],
-        toDelete: [],
-      }
+  const { toRegenerate, toDelete } = buildUtils.calcDirtyHtmlFiles(
+    store.getState()
+  )
 
   if (toRegenerate.length > 0) {
     const buildHTMLActivityProgress = reporter.createProgress(

packages/gatsby/src/commands/build.ts

@@ -233,10 +233,7 @@ module.exports = async function build(program: IBuildArgs): Promise<void> {
   workerPool.end()
   buildActivity.end()
 
-  if (
-    process.env.GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES &&
-    process.argv.includes(`--log-pages`)
-  ) {
+  if (process.argv.includes(`--log-pages`)) {
     if (toRegenerate.length) {
       report.info(
         `Built pages:\n${toRegenerate
@@ -254,10 +251,7 @@ module.exports = async function build(program: IBuildArgs): Promise<void> {
     }
   }
 
-  if (
-    process.env.GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES &&
-    process.argv.includes(`--write-to-file`)
-  ) {
+  if (process.argv.includes(`--write-to-file`)) {
     const createdFilesPath = path.resolve(
       `${program.directory}/.cache`,
       `newPages.txt`

packages/gatsby/src/services/initialize.ts

@@ -297,14 +297,12 @@ export async function initialize({
   const cacheJsonDirExists = fs.existsSync(`${cacheDirectory}/json`)
   const publicDirExists = fs.existsSync(publicDirectory)
 
-  // During builds, delete html and css files from the public directory as we don't want
-  // deleted pages and styles from previous builds to stick around.
-  // For Conditional Page Builds, we do want to remove those when there is `public` dir
-  // but cache doesn't exist
+  // For builds in case public dir exists, but cache doesn't, we need to clean up potentially stale
+  // artifacts from previous builds (due to cache not being available, we can't rely on tracking of artifacts)
   if (
     process.env.NODE_ENV === `production` &&
-    (!process.env.GATSBY_EXPERIMENTAL_PAGE_BUILD_ON_DATA_CHANGES ||
-      (publicDirExists && !cacheJsonDirExists))
+    publicDirExists &&
+    !cacheJsonDirExists
   ) {
     activity = reporter.activityTimer(
       `delete html and css files from previous builds`,