fix: support gatsby base dirs outside the site root

plugin/src/helpers/cache.ts

@@ -2,6 +2,8 @@ import path from 'path'
 
 import { existsSync, readdirSync } from 'fs-extra'
 
+import { getGatsbyRoot } from './config'
+
 function getCacheDirs(publish) {
   return [publish, normalizedCacheDir(publish)]
 }
@@ -37,5 +39,5 @@ export async function restoreCache({ publish, utils }): Promise<void> {
 }
 
 export function normalizedCacheDir(publish: string): string {
-  return path.normalize(`${publish}/../.cache`)
+  return path.join(getGatsbyRoot(publish), `.cache`)
 }

plugin/src/helpers/config.ts

@@ -38,8 +38,11 @@ export async function spliceConfig({
   return fs.writeFile(fileName, out)
 }
 
-function loadGatsbyConfig(utils): GatsbyConfig | never {
-  const gatsbyConfigFile = path.resolve(process.cwd(), 'gatsby-config.js')
+function loadGatsbyConfig({ utils, publish }): GatsbyConfig | never {
+  const gatsbyConfigFile = path.resolve(
+    getGatsbyRoot(publish),
+    'gatsby-config.js',
+  )
   if (!existsSync(gatsbyConfigFile)) {
     return {}
   }
@@ -64,7 +67,10 @@ function hasPlugin(plugins: PluginRef[], pluginName: string): boolean {
 
 export function checkGatsbyConfig({ utils, netlifyConfig }): void {
   // warn if gatsby-plugin-netlify is missing
-  const gatsbyConfig = loadGatsbyConfig(utils)
+  const gatsbyConfig = loadGatsbyConfig({
+    utils,
+    publish: netlifyConfig.build.publish,
+  })
 
   if (!hasPlugin(gatsbyConfig.plugins, 'gatsby-plugin-netlify')) {
     console.error(
@@ -152,3 +158,7 @@ export function shouldSkipFunctions(cacheDir: string): boolean {
 
   return false
 }
+
+export function getGatsbyRoot(publish: string): string {
+  return path.resolve(path.dirname(publish))
+}

plugin/src/helpers/functions.ts

@@ -1,10 +1,10 @@
-import process from 'process'
-
 import { NetlifyPluginConstants } from '@netlify/build'
 import { copy, copyFile, ensureDir, existsSync, rm, writeFile } from 'fs-extra'
 import { resolve, join, relative } from 'pathe'
 
-import { makeHandler } from '../templates/handlers'
+import { makeApiHandler, makeHandler } from '../templates/handlers'
+
+import { getGatsbyRoot } from './config'
 
 const writeFunction = async ({
   renderMode,
@@ -21,12 +21,22 @@ const writeFunction = async ({
   )
 }
 
+const writeApiFunction = async ({ appDir, functionDir }) => {
+  const source = makeApiHandler(appDir)
+  // This is to ensure we're copying from the compiled js, not ts source
+  await copy(
+    join(__dirname, '..', '..', 'lib', 'templates', 'api'),
+    functionDir,
+  )
+  await writeFile(join(functionDir, '__api.js'), source)
+}
+
 export const writeFunctions = async ({
   INTERNAL_FUNCTIONS_SRC,
   PUBLISH_DIR,
 }: NetlifyPluginConstants): Promise<void> => {
-  const siteRoot = resolve(process.cwd(), PUBLISH_DIR, '..')
-  const functionDir = join(process.cwd(), INTERNAL_FUNCTIONS_SRC, '__api')
+  const siteRoot = getGatsbyRoot(PUBLISH_DIR)
+  const functionDir = resolve(INTERNAL_FUNCTIONS_SRC, '__api')
   const appDir = relative(functionDir, siteRoot)
 
   await writeFunction({
@@ -43,17 +53,14 @@ export const writeFunctions = async ({
     functionsSrc: INTERNAL_FUNCTIONS_SRC,
   })
 
-  await copy(
-    join(__dirname, '..', '..', 'lib', 'templates', 'api'),
-    functionDir,
-  )
+  await writeApiFunction({ appDir, functionDir })
 }
 
 export const deleteFunctions = async ({
   INTERNAL_FUNCTIONS_SRC,
 }: NetlifyPluginConstants): Promise<void> => {
   for (const func of ['__api', '__ssr', '__dsg']) {
-    const funcDir = join(process.cwd(), INTERNAL_FUNCTIONS_SRC, func)
+    const funcDir = resolve(INTERNAL_FUNCTIONS_SRC, func)
     if (existsSync(funcDir)) {
       await rm(funcDir, { recursive: true, force: true })
     }

plugin/src/index.ts

@@ -24,7 +24,7 @@ export async function onPreBuild({
   netlifyConfig,
 }): Promise<void> {
   // Print a helpful message if the publish dir is misconfigured
-  if (!PUBLISH_DIR || process.cwd() === PUBLISH_DIR) {
+  if (!PUBLISH_DIR || process.cwd() === path.resolve(PUBLISH_DIR)) {
     utils.build.failBuild(
       `Gatsby sites must publish the "public" directory, but your site’s publish directory is set to “${PUBLISH_DIR}”. Please set your publish directory to your Gatsby site’s "public" directory.`,
     )

plugin/src/templates/api/gatsbyFunction.ts

@@ -23,7 +23,10 @@ export async function gatsbyFunction(
   req: AugmentedGatsbyFunctionRequest,
   res: AugmentedGatsbyFunctionResponse,
   event: HandlerEvent,
+  appDir: string,
 ) {
+  const functionsDir = path.join(appDir, '.cache', 'functions')
+
   // Multipart form data middleware. because co-body can't handle it
   await new Promise((resolve) => {
     // As we're using a fake Express handler we need to ignore the type to keep multer happy
@@ -47,7 +50,7 @@ export async function gatsbyFunction(
 
   let functions
   try {
-    functions = require('../../../.cache/functions/manifest.json')
+    functions = require(path.join(functionsDir, 'manifest.json'))
   } catch {
     return {
       statusCode: 404,
@@ -91,16 +94,7 @@ export async function gatsbyFunction(
     // During develop, the absolute path is correct, otherwise we need to use a relative path, as we're in a lambda
     const pathToFunction = process.env.NETLIFY_DEV
       ? functionObj.absoluteCompiledFilePath
-      : path.join(
-          __dirname,
-          '..',
-          '..',
-          '..',
-          // ...We got there in the end
-          '.cache',
-          'functions',
-          functionObj.relativeCompiledFilePath,
-        )
+      : path.join(functionsDir, functionObj.relativeCompiledFilePath)
 
     if (process.env.NETLIFY_DEV && !existsSync(pathToFunction)) {
       // Functions are sometimes lazily-compiled, so we check and proxy the request if needed

plugin/src/templates/handlers.ts

@@ -1,4 +1,9 @@
-import type { Handler, HandlerEvent } from '@netlify/functions'
+import type {
+  Handler,
+  HandlerContext,
+  HandlerEvent,
+  HandlerResponse,
+} from '@netlify/functions'
 import { stripIndent as javascript } from 'common-tags'
 import type { GatsbyFunctionRequest } from 'gatsby'
 import type {
@@ -14,6 +19,8 @@ const { join } = require('path')
 
 const etag = require('etag')
 
+const { gatsbyFunction } = require('./api/gatsbyFunction')
+const { createRequestObject, createResponseObject } = require('./api/utils')
 const {
   getPagePathFromPageDataPath,
   getGraphQLEngine,
@@ -127,6 +134,32 @@ const getHandler = (renderMode: RenderMode, appDir: string): Handler => {
   }
 }
 
+/**
+ * Generate an API handler
+ */
+
+const getApiHandler = (appDir: string): Handler =>
+  function handler(
+    event: HandlerEvent,
+    context: HandlerContext,
+  ): Promise<HandlerResponse> {
+    // Create a fake Gatsby/Express Request object
+    const req = createRequestObject({ event, context })
+
+    return new Promise((resolve) => {
+      // Create a stubbed Gatsby/Express Response object
+      // onResEnd is the "resolve" cb for this Promise
+      const res = createResponseObject({ onResEnd: resolve })
+      try {
+        // Try to call the actual function
+        gatsbyFunction(req, res, event, appDir)
+      } catch (error) {
+        console.error(`Error executing ${event.path}`, error)
+        resolve({ statusCode: 500 })
+      }
+    })
+  }
+
 export const makeHandler = (appDir: string, renderMode: RenderMode): string =>
   // This is a string, but if you have the right editor plugin it should format as js
   javascript`
@@ -141,6 +174,15 @@ export const makeHandler = (appDir: string, renderMode: RenderMode): string =>
         ? `builder((${getHandler.toString()})("${renderMode}", pageRoot))`
         : `((${getHandler.toString()})("${renderMode}", pageRoot))`
     }
+`
+
+export const makeApiHandler = (appDir: string): string =>
+  // This is a string, but if you have the right editor plugin it should format as js
+  javascript`
+    const { gatsbyFunction } = require('./gatsbyFunction')
+    const { createRequestObject, createResponseObject } = require('./utils')
+    const { resolve } = require("path");
 
+    const pageRoot = resolve(__dirname, "${appDir}");
+    exports.handler = ((${getApiHandler.toString()})(pageRoot))
 `
-getHandler.toString()