feat: add ability to provide existing file digest

src/commands/deploy/deploy.mjs

@@ -304,6 +304,7 @@ const runDeploy = async ({
   deployFolder,
   deployTimeout,
   deployToProduction,
+  existingFileDigest,
   functionsConfig,
   functionsFolder,
   silent,
@@ -338,6 +339,7 @@ const runDeploy = async ({
     // @ts-ignore
     results = await deploySite(api, siteId, deployFolder, {
       configPath,
+      existingFileDigest,
       fnDir: functionDirectories,
       functionsConfig,
       statusCb: silent ? () => {} : deployProgressCb(),
@@ -640,6 +642,7 @@ const deploy = async (options, command) => {
     deployFolder,
     deployTimeout: options.timeout * SEC_TO_MILLISEC || DEFAULT_DEPLOY_TIMEOUT,
     deployToProduction,
+    existingFileDigest: options.existingFileDigest,
     functionsConfig,
     // pass undefined functionsFolder if doesn't exist
     functionsFolder: functionsFolderStat && functionsFolder,
@@ -780,6 +783,11 @@ Support for package.json's main field, and intrinsic index.js entrypoints are co
       'Ignore any functions created as part of a previous `build` or `deploy` commands, forcing them to be bundled again as part of the deployment',
       false,
     )
+    .option(
+      '--existing-file-digest <json>',
+      'Preload the file digest with known existing assets for incremental deploys',
+      JSON.parse,
+    )
     .addExamples([
       'netlify deploy',
       'netlify deploy --site my-first-site',

src/utils/deploy/deploy-site.mjs

@@ -31,6 +31,7 @@ export const deploySite = async (
     deployId: deployIdOpt = null,
     deployTimeout = DEFAULT_DEPLOY_TIMEOUT,
     draft = false,
+    existingFileDigest = {},
     filter,
     fnDir = [],
     functionsConfig,
@@ -122,7 +123,7 @@ For more information, visit https://ntl.fyi/cli-native-modules.`)
   let deployParams = cleanDeep({
     siteId,
     body: {
-      files,
+      files: { ...existingFileDigest.files, ...files },
       functions,
       function_schedules: functionSchedules,
       functions_config: fnConfig,

tests/integration/incremental-site/README.md

@@ -0,0 +1,66 @@
+# Incremental Deploys
+
+In this example, we upload one directory, then we _append_ (incrementally upload) to the deploy with a new directory.
+This can be leveraged for build-time "on-demand ISR"-like capabilities with CI/CD caching the previous deploys file
+digest.
+
+1. Upload the `base-deploy` directory to a Netlify site
+
+```
+netlify deploy -d ./base-deploy
+```
+
+> ```
+> ...
+> ✔ CDN requesting 4 files
+> ...
+> ```
+
+2. Confirm file `one` exists:
+
+```
+curl -I https://$WEBSITE_DRAFT_URL/one
+```
+
+> ```
+> HTTP/2 200
+> ...
+> ```
+
+3. Upload the `new-deploy` directory, but pass the existing file digest JSON
+
+```
+netlify deploy -d ./new-deploy --existing-file-digest "$(<./base-deploy.json)"
+```
+
+> ```
+> ...
+> ✔ CDN requesting 1 files
+> ...
+> ```
+
+4. Confirm file `two` exists
+
+```
+curl -I https://$WEBSITE_DRAFT_URL/two
+```
+
+> ```
+> HTTP/2 200
+> ...
+> ```
+
+5. Confirm file `one` also _still_ exists
+
+```
+curl -I https://$WEBSITE_DRAFT_URL/one
+```
+
+> ```
+> HTTP/2 200
+> ...
+> ```
+
+```
+
+```

tests/integration/incremental-site/base-deploy.json

@@ -0,0 +1,6 @@
+{
+  "files": {
+    "netlify.toml": "395fc2be95377d1e0f95eec2cd983d7a26e48a39",
+    "one.html": "9e09cdc8f140342ddc2508380d43aa0447a46478"
+  }
+}

tests/integration/incremental-site/base-deploy/one.html

@@ -0,0 +1 @@
+a1ca9451cd6e8fc01daaa28d4becc997

tests/integration/incremental-site/new-deploy/two.html

@@ -0,0 +1 @@
+952bf0d25bdc98adede3ed91065c7dc8