Add Workflow example (#18961)

Author: JoaquinGimenez1

src/content/docs/workflows/examples/backup-d1.mdx

@@ -0,0 +1,142 @@
+---
+type: example
+summary: Backup D1 using export API and save it on R2
+tags:
+  - Workflows
+  - D1
+  - R2
+languages:
+  - Typescript
+pcx_content_type: configuration
+title: Backup and save D1 database
+sidebar:
+  order: 3
+description: Send invoice when shopping cart is checked out and paid for
+
+---
+
+import { TabItem, Tabs } from "~/components"
+
+In this example, we implement a Workflow periodically triggered by a [Cron Trigger](/workers/configuration/cron-triggers) to start a backup for a D1 database using the REST API and finally store the SQL dump in an [R2](/r2) bucket.
+
+Once a Workflow instance is triggered, fetches the REST API to start an export job for a specific database. Then, it fetches the same endpoint to check if the backup job is ready and the SQL dump is available to download.
+
+As you can see, Workflows handles the responses and failures. It will retry the API calls until we get a successful response, retry fetching the backup from the URL provided, and retry saving the file to [R2](/r2). The developer doesn't have to care about any of that logic. The workflow can run until the backup file is ready, handling all the possible conditions until it is completed.
+
+This is a simplified example of backing up a [D1](/d1) database. For every step, we use the [default](/workflows/build/sleeping-and-retrying) sleeping and retrying configuration. In a real-life scenario, we would assume more steps and additional logic, but this example gives you a good idea of what you can do with Workflows.
+
+```ts
+import {
+  WorkflowEntrypoint,
+  WorkflowStep,
+  WorkflowEvent,
+} from "cloudflare:workers";
+
+
+// We are using R2 to store the D1 backup
+type Env = {
+  BACKUP_WORKFLOW: Workflow;
+  D1_REST_API_TOKEN: string;
+  BACKUP_BUCKET: R2Bucket;
+};
+
+// Workflow parameters: we expect accountId and databaseId
+type Params = {
+  accountId: string;
+  databaseId: string;
+};
+
+// Workflow logic
+export class backupWorkflow extends WorkflowEntrypoint<Env, Params> {
+  async run(event: WorkflowEvent<Params>, step: WorkflowStep) {
+    const { accountId, databaseId } = event.payload;
+
+    const url = `https://api.cloudflare.com/client/v4/accounts/${accountId}/d1/database/${databaseId}/export`;
+    const method = "POST";
+    const headers = new Headers();
+    headers.append("Content-Type", "application/json");
+    headers.append("Authorization", `Bearer ${this.env.D1_REST_API_TOKEN}`);
+
+    const bookmark = step.do(`Starting backup for ${databaseId}`, async () => {
+      const payload = { output_format: "polling" };
+
+      const res = await fetch(url, { method, headers, body: JSON.stringify(payload) });
+      const { result } = (await res.json()) as any;
+
+      // If we don't get `at_bookmark` we throw to retry the step
+      if (!result?.at_bookmark) throw new Error("Missing `at_bookmark`");
+
+      return result.at_bookmark;
+    });
+
+    step.do("Check backup status and store it on R2", async () => {
+      const payload = { current_bookmark: bookmark };
+
+      const res = await fetch(url, { method, headers, body: JSON.stringify(payload) });
+      const { result } = (await res.json()) as any;
+
+      // The endpoint sends `signed_url` when the backup is ready to download.
+      // If we don't get `signed_url` we throw to retry the step.
+      if (!result?.signed_url) throw new Error("Missing `signed_url`");
+
+      const dumpResponse = await fetch(result.signed_url);
+      if (!dumpResponse.ok) throw new Error("Failed to fetch dump file");
+
+      // Finally, stream the file directly to R2
+      await this.env.BACKUP_BUCKET.put(result.filename, dumpResponse.body);
+    });
+  }
+}
+
+export default {
+  async fetch(req: Request, env: Env): Promise<Response> {
+    return new Response("Not found", { status: 404 });
+  },
+  async scheduled(controller: ScheduledController, env: Env, ctx: ExecutionContext) {
+    const params: Params = {
+      accountId: "{accountId}",
+      databaseId: "{databaseId}",
+    };
+    const instance = await env.BACKUP_WORKFLOW.create({ params });
+    console.log(`Started workflow: ${instance.id}`);
+  },
+};
+```
+
+Here's a minimal package.json:
+
+```json
+{
+  "devDependencies": {
+    "@cloudflare/workers-types": "^4.20241224.0",
+    "wrangler": "^3.99.0"
+  }
+}
+```
+
+And finally wrangler.toml:
+
+import { WranglerConfig } from "~/components";
+
+<WranglerConfig>
+
+```toml
+name = "backup-d1"
+main = "src/index.ts"
+compatibility_date = "2024-12-27"
+compatibility_flags = [ "nodejs_compat" ]
+
+[[workflows]]
+name = "backup-workflow"
+binding = "BACKUP_WORKFLOW"
+class_name = "backupWorkflow"
+
+[[r2_buckets]]
+binding = "BACKUP_BUCKET"
+bucket_name = "d1-backups"
+
+[triggers]
+crons = [ "0 0 * * *" ]
+```
+
+</WranglerConfig>