Cloudflare+HonoでMessaging APIのボットを動かしてみる

$ npm create hono@latest my-line-bot

$ cd my-line-bot
$ npm install @line/bot-sdk

// 末尾のカンマを追加する
"compatibility_date": "2026-09-30",
// コメントアウトを外す
"compatibility_flags": [
  "nodejs_compat"
],

import { Hono } from "hono";
import { HTTPException } from "hono/http-exception";
import { messagingApi, validateSignature, webhook } from "@line/bot-sdk";

type Bindings = {
  CHANNEL_ACCESS_TOKEN: string;
  CHANNEL_SECRET: string;
};

const app = new Hono<{ Bindings: Bindings }>();

app.post("/webhook", async (c) => {
  const body = await c.req.text();
  const signature = c.req.header("x-line-signature");

  // 署名を検証する
  if (!signature || !validateSignature(body, c.env.CHANNEL_SECRET, signature)) {
    throw new HTTPException(401, { message: "Unauthorized" });
  }

  const client = new messagingApi.MessagingApiClient({
    channelAccessToken: c.env.CHANNEL_ACCESS_TOKEN,
  });

  const data: webhook.CallbackRequest = JSON.parse(body);

  for (const event of data.events) {
    if (
      event.type === "message" &&
      event.message.type === "text" &&
      event.replyToken
    ) {
      try {
        await client.replyMessage({
          replyToken: event.replyToken,
          messages: [
            {
              type: "text",
              text: event.message.text,
            },
          ],
        });
      } catch (error) {
        throw new HTTPException(500, {
          message: "Reply API Error",
          cause: error,
        });
      }
    }
  }

  return c.text("OK");
});

export default app;

$ npx wrangler secret put CHANNEL_ACCESS_TOKEN
$ npx wrangler secret put CHANNEL_SECRET

$ npx wrangler secret put CHANNEL_ACCESS_TOKEN

 ⛅️ wrangler 4.144.0
───────────────────────────────────────────────
✔ Enter a secret value: … ****
🌀 Creating the secret for the Worker "my-line-bot"
✔ There doesn't seem to be a Worker called "my-line-bot". Do you want to create a new Worker with that name and add secrets to it? … yes
🌀 Creating new Worker "my-line-bot"...
✨ Success! Uploaded secret CHANNEL_ACCESS_TOKEN

$ npm run deploy