feat: enable API, SSR and DSG functions individually as required

plugin/src/helpers/config.ts

@@ -3,11 +3,12 @@ import { EOL } from 'os'
 import path from 'path'
 import process from 'process'
 
-import { stripIndent } from 'common-tags'
+import { NetlifyConfig } from '@netlify/build'
 import fs, { existsSync } from 'fs-extra'
 import type { GatsbyConfig, PluginRef } from 'gatsby'
 
 import { checkPackageVersion } from './files'
+import type { FunctionList } from './functions'
 
 export async function spliceConfig({
   startMarker,
@@ -114,64 +115,126 @@ export async function checkConfig({ utils, netlifyConfig }): Promise<void> {
   }
 }
 
+export async function modifyConfig({
+  netlifyConfig,
+  cacheDir,
+  neededFunctions,
+}: {
+  netlifyConfig: NetlifyConfig
+  cacheDir: string
+  neededFunctions: FunctionList
+}): Promise<void> {
+  mutateConfig({ netlifyConfig, cacheDir, neededFunctions })
+
+  if (neededFunctions.includes('API')) {
+    // Editing _redirects so it works with ntl dev
+    await spliceConfig({
+      startMarker: '# @netlify/plugin-gatsby redirects start',
+      endMarker: '# @netlify/plugin-gatsby redirects end',
+      contents: '/api/* /.netlify/functions/__api 200',
+      fileName: path.join(netlifyConfig.build.publish, '_redirects'),
+    })
+  }
+}
+
 export function mutateConfig({
   netlifyConfig,
-  compiledFunctionsDir,
   cacheDir,
+  neededFunctions,
+}: {
+  netlifyConfig: NetlifyConfig
+  cacheDir: string
+  neededFunctions: FunctionList
 }): void {
   /* eslint-disable no-underscore-dangle, no-param-reassign */
-  netlifyConfig.functions.__api = {
-    included_files: [path.posix.join(compiledFunctionsDir, '**')],
-    external_node_modules: ['msgpackr-extract'],
+  if (neededFunctions.includes('API')) {
+    netlifyConfig.functions.__api = {
+      included_files: [path.posix.join(cacheDir, 'functions', '**')],
+      external_node_modules: ['msgpackr-extract'],
+    }
   }
 
-  netlifyConfig.functions.__dsg = {
-    included_files: [
-      'public/404.html',
-      'public/500.html',
-      path.posix.join(cacheDir, 'data', '**'),
-      path.posix.join(cacheDir, 'query-engine', '**'),
-      path.posix.join(cacheDir, 'page-ssr', '**'),
-      '!**/*.js.map',
-    ],
-    external_node_modules: ['msgpackr-extract'],
-    node_bundler: 'esbuild',
+  if (neededFunctions.includes('DSG')) {
+    netlifyConfig.functions.__dsg = {
+      included_files: [
+        'public/404.html',
+        'public/500.html',
+        path.posix.join(cacheDir, 'data', '**'),
+        path.posix.join(cacheDir, 'query-engine', '**'),
+        path.posix.join(cacheDir, 'page-ssr', '**'),
+        '!**/*.js.map',
+      ],
+      external_node_modules: ['msgpackr-extract'],
+      node_bundler: 'esbuild',
+    }
   }
 
-  netlifyConfig.functions.__ssr = { ...netlifyConfig.functions.__dsg }
+  if (neededFunctions.includes('SSR')) {
+    netlifyConfig.functions.__ssr = {
+      included_files: [
+        'public/404.html',
+        'public/500.html',
+        path.posix.join(cacheDir, 'data', '**'),
+        path.posix.join(cacheDir, 'query-engine', '**'),
+        path.posix.join(cacheDir, 'page-ssr', '**'),
+        '!**/*.js.map',
+      ],
+      external_node_modules: ['msgpackr-extract'],
+      node_bundler: 'esbuild',
+    }
+  }
   /* eslint-enable no-underscore-dangle, no-param-reassign */
 }
 
-export function shouldSkipFunctions(cacheDir: string): boolean {
-  if (
-    process.env.NETLIFY_SKIP_GATSBY_FUNCTIONS === 'true' ||
-    process.env.NETLIFY_SKIP_GATSBY_FUNCTIONS === '1'
-  ) {
-    console.log(
-      'Skipping Gatsby Functions and SSR/DSG support because the environment variable NETLIFY_SKIP_GATSBY_FUNCTIONS is set to true',
-    )
-    return true
-  }
+export async function getNeededFunctions(
+  cacheDir: string,
+): Promise<FunctionList> {
+  if (!existsSync(path.join(cacheDir, 'functions'))) return []
 
-  if (!existsSync(path.join(cacheDir, 'functions'))) {
-    console.log(
-      `Skipping Gatsby Functions and SSR/DSG support because the site's Gatsby version does not support them`,
-    )
-    return true
+  const neededFunctions = overrideNeededFunctions(
+    await readFunctionSkipFile(cacheDir),
+  )
+
+  const functionList = Object.keys(neededFunctions).filter(
+    (name) => neededFunctions[name] === true,
+  ) as FunctionList
+
+  if (functionList.length === 0) {
+    console.log('Skipping Gatsby Functions and SSR/DSG support')
+  } else {
+    console.log(`Enabling Gatsby ${functionList.join('/')} support`)
   }
 
-  const skipFile = path.join(cacheDir, '.nf-skip-gatsby-functions')
+  return functionList
+}
+
+async function readFunctionSkipFile(cacheDir: string) {
+  try {
+    // read skip file from gatsby-plugin-netlify
+    return await fs.readJson(path.join(cacheDir, '.nf-skip-gatsby-functions'))
+  } catch (error) {
+    // missing skip file = all functions needed
+    // empty or invalid skip file = no functions needed
+    return error.code === 'ENOENT' ? { API: true, SSR: true, DSG: true } : {}
+  }
+}
 
-  if (existsSync(skipFile)) {
-    console.log(
-      stripIndent`
-      Skipping Gatsby Functions and SSR/DSG support because gatsby-plugin-netlify reported that this site does not use them. 
-      If this is incorrect, remove the file "${skipFile}" and try again.`,
-    )
-    return true
+// eslint-disable-next-line complexity
+function overrideNeededFunctions(neededFunctions) {
+  const skipAll = isEnvSet('NETLIFY_SKIP_GATSBY_FUNCTIONS')
+  const skipAPI = isEnvSet('NETLIFY_SKIP_API_FUNCTION')
+  const skipSSR = isEnvSet('NETLIFY_SKIP_SSR_FUNCTION')
+  const skipDSG = isEnvSet('NETLIFY_SKIP_DSG_FUNCTION')
+
+  return {
+    API: skipAll || skipAPI ? false : neededFunctions.API,
+    SSR: skipAll || skipSSR ? false : neededFunctions.SSR,
+    DSG: skipAll || skipDSG ? false : neededFunctions.DSG,
   }
+}
 
-  return false
+function isEnvSet(envVar: string) {
+  return process.env[envVar] === 'true' || process.env[envVar] === '1'
 }
 
 export function getGatsbyRoot(publish: string): string {

plugin/src/helpers/files.ts

@@ -1,6 +1,7 @@
 import os from 'os'
 import process from 'process'
 
+import { NetlifyConfig } from '@netlify/build'
 import {
   copyFile,
   ensureDir,
@@ -12,6 +13,8 @@ import {
 import { dirname, join, resolve } from 'pathe'
 import semver from 'semver'
 
+import type { FunctionList } from './functions'
+
 const DEFAULT_LAMBDA_PLATFORM = 'linux'
 const DEFAULT_LAMBDA_ABI = '83'
 const DEFAULT_LAMBDA_ARCH = 'x64'
@@ -23,6 +26,20 @@ const RELOCATABLE_BINARIES = [
   `node.abi${DEFAULT_LAMBDA_ABI}.glibc.node`,
 ]
 
+export const modifyFiles = async ({
+  netlifyConfig,
+  neededFunctions,
+}: {
+  netlifyConfig: NetlifyConfig
+  neededFunctions: FunctionList
+}): Promise<void> => {
+  if (neededFunctions.includes('SSR') || neededFunctions.includes('DSG')) {
+    const root = dirname(netlifyConfig.build.publish)
+    await patchFile(root)
+    await relocateBinaries(root)
+  }
+}
+
 /**
  * Manually patching the bundle to work around various incompatibilities in some versions.
  */

plugin/src/helpers/functions.ts

@@ -6,6 +6,8 @@ import { makeApiHandler, makeHandler } from '../templates/handlers'
 
 import { getGatsbyRoot } from './config'
 
+export type FunctionList = Array<'API' | 'SSR' | 'DSG'>
+
 const writeFunction = async ({
   renderMode,
   handlerName,
@@ -34,30 +36,40 @@ const writeApiFunction = async ({ appDir, functionDir }) => {
 export const writeFunctions = async ({
   constants,
   netlifyConfig,
+  neededFunctions,
 }: {
   constants: NetlifyPluginConstants
   netlifyConfig: NetlifyConfig
+  neededFunctions: FunctionList
 }): Promise<void> => {
   const { PUBLISH_DIR, INTERNAL_FUNCTIONS_SRC } = constants
   const siteRoot = getGatsbyRoot(PUBLISH_DIR)
   const functionDir = resolve(INTERNAL_FUNCTIONS_SRC, '__api')
   const appDir = relative(functionDir, siteRoot)
 
-  await writeFunction({
-    renderMode: 'SSR',
-    handlerName: '__ssr',
-    appDir,
-    functionsSrc: INTERNAL_FUNCTIONS_SRC,
-  })
+  if (neededFunctions.includes('SSR')) {
+    await writeFunction({
+      renderMode: 'SSR',
+      handlerName: '__ssr',
+      appDir,
+      functionsSrc: INTERNAL_FUNCTIONS_SRC,
+    })
+  }
+
+  if (neededFunctions.includes('DSG')) {
+    await writeFunction({
+      renderMode: 'DSG',
+      handlerName: '__dsg',
+      appDir,
+      functionsSrc: INTERNAL_FUNCTIONS_SRC,
+    })
+  }
 
-  await writeFunction({
-    renderMode: 'DSG',
-    handlerName: '__dsg',
-    appDir,
-    functionsSrc: INTERNAL_FUNCTIONS_SRC,
-  })
   await setupImageCdn({ constants, netlifyConfig })
-  await writeApiFunction({ appDir, functionDir })
+
+  if (neededFunctions.includes('API')) {
+    await writeApiFunction({ appDir, functionDir })
+  }
 }
 
 export const setupImageCdn = async ({

plugin/src/index.ts

@@ -1,18 +1,13 @@
-import path, { dirname, join } from 'path'
+import path from 'path'
 import process from 'process'
 
 import { NetlifyPluginOptions } from '@netlify/build'
 import { stripIndent } from 'common-tags'
 import { existsSync } from 'fs-extra'
 
 import { normalizedCacheDir, restoreCache, saveCache } from './helpers/cache'
-import {
-  checkConfig,
-  mutateConfig,
-  shouldSkipFunctions,
-  spliceConfig,
-} from './helpers/config'
-import { patchFile, relocateBinaries } from './helpers/files'
+import { checkConfig, getNeededFunctions, modifyConfig } from './helpers/config'
+import { modifyFiles } from './helpers/files'
 import { deleteFunctions, writeFunctions } from './helpers/functions'
 import { checkZipSize } from './helpers/verification'
 
@@ -58,35 +53,28 @@ export async function onBuild({
 The plugin no longer uses this and it should be deleted to avoid conflicts.\n`)
   }
 
-  if (shouldSkipFunctions(cacheDir)) {
-    await deleteFunctions(constants)
-    return
-  }
-  const compiledFunctionsDir = path.join(cacheDir, '/functions')
+  const neededFunctions = await getNeededFunctions(cacheDir)
 
-  await writeFunctions({ constants, netlifyConfig })
+  await deleteFunctions(constants)
 
-  mutateConfig({ netlifyConfig, cacheDir, compiledFunctionsDir })
+  await writeFunctions({ constants, netlifyConfig, neededFunctions })
 
-  const root = dirname(netlifyConfig.build.publish)
-  await patchFile(root)
-  await relocateBinaries(root)
+  await modifyConfig({ netlifyConfig, cacheDir, neededFunctions })
 
-  // Editing _redirects so it works with ntl dev
-  spliceConfig({
-    startMarker: '# @netlify/plugin-gatsby redirects start',
-    endMarker: '# @netlify/plugin-gatsby redirects end',
-    contents: '/api/* /.netlify/functions/__api 200',
-    fileName: join(netlifyConfig.build.publish, '_redirects'),
-  })
+  await modifyFiles({ netlifyConfig, neededFunctions })
 }
 
 export async function onPostBuild({
   constants: { PUBLISH_DIR, FUNCTIONS_DIST },
   utils,
 }): Promise<void> {
   await saveCache({ publish: PUBLISH_DIR, utils })
-  for (const func of ['api', 'dsg', 'ssr']) {
-    await checkZipSize(path.join(FUNCTIONS_DIST, `__${func}.zip`))
+
+  const cacheDir = normalizedCacheDir(PUBLISH_DIR)
+
+  const neededFunctions = await getNeededFunctions(cacheDir)
+
+  for (const func of neededFunctions) {
+    await checkZipSize(path.join(FUNCTIONS_DIST, `__${func.toLowerCase()}.zip`))
   }
 }