feat: auto-install gatsby plugin

plugin/package.json

@@ -47,6 +47,7 @@
     "download": "^8.0.0",
     "etag": "^1.8.1",
     "fs-extra": "^10.0.0",
+    "gatsby-plugin-netlify": "^4.1.0",
     "linkfs": "^2.1.0",
     "multer": "^1.4.2",
     "node-fetch": "^2.6.1",

plugin/src/helpers/config.ts

@@ -1,10 +1,14 @@
+/* eslint-disable max-lines */
 import { EOL } from 'os'
 import path from 'path'
 import process from 'process'
 
 import { stripIndent } from 'common-tags'
-import fs, { existsSync } from 'fs-extra'
+import fs, { existsSync, move, writeFile } from 'fs-extra'
 import type { GatsbyConfig, PluginRef } from 'gatsby'
+import { relative } from 'pathe'
+
+import { getGatsbyConfigWrapper } from '../templates/gatsby-config'
 
 export async function spliceConfig({
   startMarker,
@@ -62,14 +66,47 @@ function hasPlugin(plugins: PluginRef[], pluginName: string): boolean {
   )
 }
 
-export function checkGatsbyConfig({ utils, netlifyConfig }): void {
+function hasAutoInstall(
+  // eslint-disable-next-line camelcase
+  plugins: Array<PluginRef & { __nf_auto?: true }>,
+): boolean {
+  // eslint-disable-next-line no-underscore-dangle
+  return plugins?.some((plugin) => plugin.__nf_auto)
+}
+
+/**
+ * Wrap the Gatsby config to inject the Netlify plugin
+ */
+export async function wrapGatsbyConfig() {
+  const configFile = path.resolve(process.cwd(), 'gatsby-config.js')
+  if (!existsSync(configFile)) {
+    console.error('Could not find Gatsby config')
+    return
+  }
+  await move(configFile, path.resolve(process.cwd(), 'gatsby-config-orig.js'))
+
+  const pluginRoot = require.resolve('gatsby-plugin-netlify')
+
+  const pluginPath = relative(process.cwd(), pluginRoot)
+  console.log({ pluginPath, pluginRoot })
+  await writeFile(configFile, getGatsbyConfigWrapper(pluginPath))
+}
+
+export async function checkGatsbyConfig({
+  utils,
+  netlifyConfig,
+}): Promise<void> {
   // warn if gatsby-plugin-netlify is missing
   const gatsbyConfig = loadGatsbyConfig(utils)
 
-  if (!hasPlugin(gatsbyConfig.plugins, 'gatsby-plugin-netlify')) {
+  if (
+    !hasPlugin(gatsbyConfig.plugins, 'gatsby-plugin-netlify') &&
+    !hasAutoInstall(gatsbyConfig.plugins)
+  ) {
     console.error(
       'Please install `gatsby-plugin-netlify` and enable it in your gatsby-config.js. https://www.gatsbyjs.com/plugins/gatsby-plugin-netlify/',
     )
+    await wrapGatsbyConfig()
   }
 
   if (hasPlugin(gatsbyConfig.plugins, 'gatsby-plugin-netlify-cache')) {
@@ -152,3 +189,4 @@ export function shouldSkipFunctions(cacheDir: string): boolean {
 
   return false
 }
+/* eslint-enable max-lines */

plugin/src/index.ts

@@ -31,7 +31,7 @@ export async function onPreBuild({
   }
   await restoreCache({ utils, publish: PUBLISH_DIR })
 
-  checkGatsbyConfig({ utils, netlifyConfig })
+  await checkGatsbyConfig({ utils, netlifyConfig })
 }
 
 export async function onBuild({

plugin/src/templates/gatsby-config.ts

@@ -0,0 +1,18 @@
+import { stripIndent as javascript } from 'common-tags'
+
+export const getGatsbyConfigWrapper = (pluginPath: string): string =>
+  // A string, but with the right editor plugin this will format as JS
+  javascript`
+
+const originalConfig = require('./gatsby-config-orig')
+module.exports = {
+  ...originalConfig,
+  plugins: [
+    ...originalConfig.plugins,
+    {
+      resolve: require.resolve("${pluginPath}"),
+      "__nf_auto": true
+    },
+  ],
+}
+`

plugin/test/fixtures/functions-without-gatsby-plugin/gatsby-config.js

@@ -1,7 +1,4 @@
 module.exports = {
-  flags: {
-    FUNCTIONS: true,
-  },
   siteMetadata: {
     title: 'Function test',
   },

plugin/test/fixtures/functions-without-gatsby-plugin/package.json

@@ -20,7 +20,7 @@
     "test:jest": "jest"
   },
   "dependencies": {
-    "gatsby": "^4.5.4",
+    "gatsby": "latest",
     "react": "^17.0.1",
     "react-dom": "^17.0.1"
   },