feat: add opt-in mechanisms via FF and env var

Author: pieh

src/build/skew-protection.ts

@@ -1,14 +1,32 @@
 import { mkdir, writeFile } from 'node:fs/promises'
 import { dirname } from 'node:path'
 
-import { PluginContext } from './plugin-context.js'
+import type { Span } from '@opentelemetry/api'
 
-export const setSkewProtection = async (ctx: PluginContext) => {
+import type { PluginContext } from './plugin-context.js'
+
+export const setSkewProtection = async (ctx: PluginContext, span: Span) => {
   if (!process.env.DEPLOY_ID || process.env.DEPLOY_ID === '0') {
+    // We can't proceed without a valid DEPLOY_ID, this should only be the case for CLI deploys
+    span.setAttribute('skewProtection', 'off-no-valid-deploy-id')
     return
   }
 
-  console.log('[Next Runtime] Setting up Next.js Skew Protection')
+  if (ctx.featureFlags?.['next-runtime-skew-protection']) {
+    console.log('Setting up Next.js Skew Protection')
+    span.setAttribute('skewProtection', 'ff-opt-in')
+  } else if (
+    process.env.NETLIFY_NEXT_PLUGIN_SKEW_PROTECTION === 'true' ||
+    process.env.NETLIFY_NEXT_PLUGIN_SKEW_PROTECTION === '1'
+  ) {
+    console.log(
+      'Setting up Next.js Skew Protection due to NETLIFY_NEXT_PLUGIN_SKEW_PROTECTION environment variable',
+    )
+    span.setAttribute('skewProtection', 'env-var-opt-in')
+  } else {
+    span.setAttribute('skewProtection', 'off')
+    return
+  }
 
   process.env.NEXT_DEPLOYMENT_ID = process.env.DEPLOY_ID
 

src/index.ts

@@ -50,7 +50,7 @@ export const onPreBuild = async (options: NetlifyPluginOptions) => {
     return
   }
 
-  await tracer.withActiveSpan('onPreBuild', async () => {
+  await tracer.withActiveSpan('onPreBuild', async (span) => {
     // Enable Next.js standalone mode at build time
     process.env.NEXT_PRIVATE_STANDALONE = 'true'
     const ctx = new PluginContext(options)
@@ -63,7 +63,7 @@ export const onPreBuild = async (options: NetlifyPluginOptions) => {
     } else {
       await restoreBuildCache(ctx)
     }
-    await setSkewProtection(ctx)
+    await setSkewProtection(ctx, span)
   })
 }