feat: warn if zip is too large, and log the largest files

package.json

@@ -58,8 +58,10 @@
     "chalk": "^4.1.2",
     "fs-extra": "^10.0.0",
     "moize": "^6.1.0",
+    "node-stream-zip": "^1.15.0",
     "outdent": "^0.8.0",
     "pathe": "^0.2.0",
+    "pretty-bytes": "^5.6.0",
     "semver": "^7.3.5",
     "slash": "^3.0.0",
     "tiny-glob": "^0.2.9"

src/helpers/verification.js

@@ -1,8 +1,11 @@
+const { existsSync, promises } = require('fs')
 const path = require('path')
+const { relative } = require('path')
 
-const { yellowBright, greenBright, blueBright } = require('chalk')
-const { existsSync } = require('fs-extra')
+const { yellowBright, greenBright, blueBright, redBright } = require('chalk')
+const { async: StreamZip } = require('node-stream-zip')
 const outdent = require('outdent')
+const prettyBytes = require('pretty-bytes')
 const { satisfies } = require('semver')
 
 exports.verifyBuildTarget = (target) => {
@@ -53,6 +56,42 @@ exports.checkForRootPublish = ({ publish, failBuild }) => {
   }
 }
 
+// 50MB, which is the documented max, though the hard max seems to be higher
+const LAMBDA_MAX_SIZE = 1024 * 1024 * 50
+
+exports.checkZipSize = async (file) => {
+  const size = await promises.stat(file).then(({ size }) => size)
+  if (size < LAMBDA_MAX_SIZE) {
+    return
+  }
+  // We don't fail the build, because the actual hard max size is larger so it might still succeed
+  console.log(
+    redBright(outdent`
+
+    The function zip ${yellowBright(relative(process.cwd(), file))} size is ${prettyBytes(
+      size,
+    )}, which is larger than the maximum supported size of ${prettyBytes(LAMBDA_MAX_SIZE)}.
+    There are a few reasons this could happen. You may have accidentally bundled a large dependency, or you might have a
+    large number of pre-rendered pages included.
+
+    `),
+  )
+  const zip = new StreamZip({ file })
+  console.log(`Contains ${await zip.entriesCount} files`)
+  const sortedFiles = Object.values(await zip.entries()).sort((a, b) => b.size - a.size)
+
+  const largest = {}
+  for (let i = 0; i < 10; i++) {
+    largest[`${i + 1}`] = {
+      File: sortedFiles[i].name,
+      'Compressed Size': prettyBytes(sortedFiles[i].compressedSize),
+      'Uncompressed Size': prettyBytes(sortedFiles[i].size),
+    }
+  }
+  console.log(yellowBright`\n\nThese are the largest files in the zip:`)
+  console.table(largest)
+}
+
 exports.logBetaMessage = () =>
   console.log(
     greenBright(

src/index.js

@@ -4,6 +4,7 @@ const { join, relative } = require('path')
 
 const { copy, existsSync } = require('fs-extra')
 
+const { ODB_FUNCTION_NAME } = require('./constants')
 const { restoreCache, saveCache } = require('./helpers/cache')
 const { getNextConfig, configureHandlerFunctions, generateRedirects } = require('./helpers/config')
 const { generateFunctions, setupImageFunction, generatePagesResolver } = require('./helpers/functions')
@@ -13,6 +14,7 @@ const {
   verifyBuildTarget,
   checkForRootPublish,
   logBetaMessage,
+  checkZipSize,
 } = require('./helpers/verification')
 
 module.exports = {
@@ -65,8 +67,9 @@ module.exports = {
     })
   },
 
-  async onPostBuild({ netlifyConfig, utils: { cache } }) {
-    return saveCache({ cache, publish: netlifyConfig.build.publish })
+  async onPostBuild({ netlifyConfig, utils: { cache }, constants }) {
+    await saveCache({ cache, publish: netlifyConfig.build.publish })
+    await checkZipSize(join(process.cwd(), constants.FUNCTIONS_DIST, `${ODB_FUNCTION_NAME}.zip`))
   },
   onEnd() {
     logBetaMessage()

test/index.js

@@ -14,6 +14,7 @@ const SAMPLE_PROJECT_DIR = `${__dirname}/../demo`
 const constants = {
   INTERNAL_FUNCTIONS_SRC: '.netlify/internal-functions',
   PUBLISH_DIR: '.next',
+  FUNCTIONS_DIST: '.netlify/functions',
 }
 const utils = {
   build: {