revalidation relies on the expires header

serverless-nextjs · Apr 29, 2021 · 8a0d5ff · 8a0d5ff
1 parent fc8bd38
commit 8a0d5ff
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Showing 4 changed files with 123 additions and 71 deletions.
diff --git a/packages/libs/lambda-at-edge/src/default-handler.ts b/packages/libs/lambda-at-edge/src/default-handler.ts
@@ -47,6 +47,7 @@ import { removeBlacklistedHeaders } from "./headers/removeBlacklistedHeaders";
 import { getStaticRegenerationResponse } from "./lib/getStaticRegenerationResponse";
 import { s3BucketNameFromEventRequest } from "./s3/s3BucketNameFromEventRequest";
 import { triggerStaticRegeneration } from "./lib/triggerStaticRegeneration";
+import { s3StorePage } from "./s3/s3StorePage";
 
 const basePath = RoutesManifestJson.basePath;
 
@@ -617,6 +618,7 @@ const handleOriginResponse = async ({
     const staticRegenerationResponse = getStaticRegenerationResponse({
       requestedOriginUri: uri,
       expiresHeader: response.headers.expires?.[0]?.value || "",
+      lastModifiedHeader: response.headers["last-modified"]?.[0]?.value || "",
       manifest
     });
 
@@ -694,33 +696,16 @@ const handleOriginResponse = async ({
       "passthrough"
     );
     if (isSSG) {
-      const baseKey = uri
-        .replace(/^\//, "")
-        .replace(/\.(json|html)$/, "")
-        .replace(/^_next\/data\/[^\/]*\//, "");
-      const jsonKey = `_next/data/${manifest.buildId}/${baseKey}.json`;
-      const htmlKey = `static-pages/${manifest.buildId}/${baseKey}.html`;
-      const s3JsonParams = {
-        Bucket: bucketName,
-        Key: `${s3BasePath}${jsonKey}`,
-        Body: JSON.stringify(renderOpts.pageData),
-        ContentType: "application/json",
-        CacheControl: "public, max-age=0, s-maxage=2678400, must-revalidate"
-      };
-      const s3HtmlParams = {
-        Bucket: bucketName,
-        Key: `${s3BasePath}${htmlKey}`,
-        Body: html,
-        ContentType: "text/html",
-        CacheControl: "public, max-age=0, s-maxage=2678400, must-revalidate"
-      };
-      const { PutObjectCommand } = await import(
-        "@aws-sdk/client-s3/commands/PutObjectCommand"
-      );
-      await Promise.all([
-        s3.send(new PutObjectCommand(s3JsonParams)),
-        s3.send(new PutObjectCommand(s3HtmlParams))
-      ]);
+      await s3StorePage({
+        html,
+        uri,
+        basePath,
+        bucketName: bucketName || "",
+        buildId: manifest.buildId,
+        pageData: renderOpts.pageData,
+        region: request.origin?.s3?.region || "",
+        revalidate: renderOpts.revalidate
+      });
     }
     const outHeaders: OutgoingHttpHeaders = {};
     Object.entries(response.headers).map(([name, headers]) => {

diff --git a/packages/libs/lambda-at-edge/src/lib/getStaticRegenerationResponse.ts b/packages/libs/lambda-at-edge/src/lib/getStaticRegenerationResponse.ts
@@ -5,6 +5,7 @@ interface StaticRegenerationResponseOptions {
   requestedOriginUri: string;
   // Header as set on the origin object
   expiresHeader: string;
+  lastModifiedHeader: string;
   manifest: OriginRequestDefaultHandlerManifest;
 }
 
@@ -14,6 +15,15 @@ interface StaticRegenerationResponseValue {
   secondsRemainingUntilRevalidation: number;
 }
 
+const firstRegenerateExpiryDate = (
+  lastModifiedHeader: string,
+  initialRevalidateSeconds: number
+) => {
+  return new Date(
+    new Date(lastModifiedHeader).getTime() + initialRevalidateSeconds * 1000
+  );
+};
+
 /**
  * Function called within an origin response as part of the Incremental Static
  * Regeneration logic. Returns required headers for the response, or false if
@@ -27,13 +37,26 @@ const getStaticRegenerationResponse = (
       options.requestedOriginUri.replace(".html", "")
     ]?.initialRevalidateSeconds;
 
-  // If this page did not write a revalidate value at build time it is not an
-  // ISR page
-  if (typeof initialRevalidateSeconds !== "number") {
+  // ISR pages that were either previously regenerated or generated
+  // post-initial-build, will have an `Expires` header set. However ISR pages
+  // that have not been regenerated but at build-time resolved a revalidate
+  // property will not have an `Expires` header and therefore we check using the
+  // manifest.
+  if (
+    !options.expiresHeader &&
+    !(
+      options.lastModifiedHeader && typeof initialRevalidateSeconds === "number"
+    )
+  ) {
     return false;
   }
 
-  const expiresAt = new Date(options.expiresHeader);
+  const expiresAt = options.expiresHeader
+    ? new Date(options.expiresHeader)
+    : firstRegenerateExpiryDate(
+        options.lastModifiedHeader,
+        initialRevalidateSeconds as number
+      );
 
   // isNaN will resolve true on initial load of this page (as the expiresHeader
   // won't be set), in which case we trigger a regeneration now

diff --git a/packages/libs/lambda-at-edge/src/regeneration-handler.ts b/packages/libs/lambda-at-edge/src/regeneration-handler.ts
@@ -1,7 +1,6 @@
 import lambdaAtEdgeCompat from "@sls-next/next-aws-cloudfront";
 import { OriginRequestDefaultHandlerManifest } from "./types";
-import { S3Client } from "@aws-sdk/client-s3";
-import { buildS3RetryStrategy } from "./s3/s3RetryStrategy";
+import { s3StorePage } from "./s3/s3StorePage";
 
 export const handler: AWSLambda.SQSHandler = async (event) => {
   await Promise.all(
@@ -29,12 +28,6 @@ export const handler: AWSLambda.SQSHandler = async (event) => {
         manifestString
       );
 
-      const s3 = new S3Client({
-        region: cloudFrontEventRequest.origin?.s3?.region,
-        maxAttempts: 3,
-        retryStrategy: await buildS3RetryStrategy()
-      });
-
       const { req, res } = lambdaAtEdgeCompat(
         { request: cloudFrontEventRequest },
         { enableHTTPCompression: manifest.enableHTTPCompression }
@@ -50,44 +43,22 @@ export const handler: AWSLambda.SQSHandler = async (event) => {
       // eslint-disable-next-line @typescript-eslint/no-var-requires
       const page = require(`./pages${srcPath}`);
 
-      const jsonKey = `_next/data/${manifest.buildId}${baseKey}.json`;
-      const htmlKey = `static-pages/${manifest.buildId}${baseKey}.html`;
-
       const { renderOpts, html } = await page.renderReqToHTML(
         req,
         res,
         "passthrough"
       );
 
-      const revalidate =
-        renderOpts.revalidate ?? ssgRoute.initialRevalidateSeconds;
-      const expires = new Date(Date.now() + revalidate * 1000);
-      const s3BasePath = basePath ? `${basePath.replace(/^\//, "")}/` : "";
-      const s3JsonParams = {
-        Bucket: bucketName,
-        Key: `${s3BasePath}${jsonKey}`,
-        Body: JSON.stringify(renderOpts.pageData),
-        ContentType: "application/json",
-        Expires: expires,
-        CacheControl: "public, max-age=0, s-maxage=2678400, must-revalidate"
-      };
-
-      const s3HtmlParams = {
-        Bucket: bucketName,
-        Key: `${s3BasePath}${htmlKey}`,
-        Body: html,
-        ContentType: "text/html",
-        Expires: expires,
-        CacheControl: "public, max-age=0, s-maxage=2678400, must-revalidate"
-      };
-
-      const { PutObjectCommand } = await import(
-        "@aws-sdk/client-s3/commands/PutObjectCommand"
-      );
-      await Promise.all([
-        s3.send(new PutObjectCommand(s3JsonParams)),
-        s3.send(new PutObjectCommand(s3HtmlParams))
-      ]);
+      await s3StorePage({
+        html,
+        uri: cloudFrontEventRequest.uri,
+        basePath,
+        bucketName: bucketName || "",
+        buildId: manifest.buildId,
+        pageData: renderOpts.pageData,
+        region: cloudFrontEventRequest.origin?.s3?.region || "",
+        revalidate: renderOpts.revalidate
+      });
     })
   );
 };
diff --git a/packages/libs/lambda-at-edge/src/s3/s3StorePage.ts b/packages/libs/lambda-at-edge/src/s3/s3StorePage.ts
@@ -0,0 +1,73 @@
+import { buildS3RetryStrategy } from "./s3RetryStrategy";
+
+interface S3StorePageOptions {
+  basePath: string | undefined;
+  uri: string;
+  revalidate?: number | undefined;
+  bucketName: string;
+  html: string;
+  buildId: string;
+  region: string;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  pageData: Record<string, any>;
+}
+
+/**
+ * There are multiple occasions where a static/SSG page will be generated after
+ * the initial build. This function accepts a generated page, stores it and
+ * applies the appropriate headers (e.g. setting an 'Expires' header for
+ * regeneration).
+ */
+export const s3StorePage = async (
+  options: S3StorePageOptions
+): Promise<void> => {
+  const { S3Client } = await import("@aws-sdk/client-s3/S3Client");
+
+  const s3 = new S3Client({
+    region: options.region,
+    maxAttempts: 3,
+    retryStrategy: await buildS3RetryStrategy()
+  });
+
+  const s3BasePath = options.basePath
+    ? `${options.basePath.replace(/^\//, "")}/`
+    : "";
+  const baseKey = options.uri
+    .replace(/^\//, "")
+    .replace(/\.(json|html)$/, "")
+    .replace(/^_next\/data\/[^\/]*\//, "");
+  const jsonKey = `_next/data/${options.buildId}/${baseKey}.json`;
+  const htmlKey = `static-pages/${options.buildId}/${baseKey}.html`;
+  const cacheControl = options.revalidate
+    ? undefined
+    : "public, max-age=0, s-maxage=2678400, must-revalidate";
+  const expires = options.revalidate
+    ? new Date(new Date().getTime() + 1000 * options.revalidate)
+    : undefined;
+
+  const s3JsonParams = {
+    Bucket: options.bucketName,
+    Key: `${s3BasePath}${jsonKey}`,
+    Body: JSON.stringify(options.pageData),
+    ContentType: "application/json",
+    CacheControl: cacheControl,
+    Expires: expires
+  };
+
+  const s3HtmlParams = {
+    Bucket: options.bucketName,
+    Key: `${s3BasePath}${htmlKey}`,
+    Body: options.html,
+    ContentType: "text/html",
+    CacheControl: cacheControl,
+    Expires: expires
+  };
+
+  const { PutObjectCommand } = await import(
+    "@aws-sdk/client-s3/commands/PutObjectCommand"
+  );
+  await Promise.all([
+    s3.send(new PutObjectCommand(s3JsonParams)),
+    s3.send(new PutObjectCommand(s3HtmlParams))
+  ]);
+};