GCP Javascript 複合機で受信したFAXをMattermostに投稿(PNGを投稿+PDFへのリンク)

以前からFAXをオンラインで確認できるようにしたいと思っていて､数ヶ月前からMattermostを利用し始めたこともあり､Mattermostで受信できるようにしてみた｡

複合機が送信したPDF付きメールをGmailで受信し､GASでGoogleDriveからMattermostに投稿してみたが､PDFがサムネイル表示されなかった｡ファイル名が自動採番なのでサムネイルは必須であり､そこでPDFからPNGを生成するCloud Runを作成することにした｡

Cloud Runを利用し､PDFはGoogleDriveに保存したままPNGをMattermostに投稿､PNGのリンク先にGoogleDriveのPDFを指定することにした｡

●Cloud Run

･プロジェクトを作成｡
※ここでは､PDF2PNGというプロジェクトを作成した
･Cloud Runというプロダクトを選択し､サービスを作成する
･請求アカウントを作成(請求アカウントがないとサービスが作成できない)
※ここでは､個人クレジットカードというアカウントを作成した
･インラインエディタで関数を作成する
･サービス名：pdf2pngとした
･リージョン：そのまま
･ランタイム：Node.js 20
･承認：未認証の呼び出しを許可
･課金：リクエストベース
･インスタンスの最小数：0
･Ingress：すべて
※Cloud Build APIを有効にする必要があるとでるのでここで有効
･エディタが開くのでindex.js､package.jsonを記入
ベースイメージ: Node.js 20 (Ubuntu 22)を選択
･関数のエントリポイントを空白のまま
※ここを空白にしないとエラーになる
･保存して再デプロイを実施
･URLが表示されるので､変換できるかcurlでテスト
curl -X POST -F “file=@./xxx.pdf” https://xxx.run.app -o output.png

index.js

const express = require("express");
const multer = require("multer");
const { pdfToPng } = require("pdf-to-png-converter");
const app = express();
const upload = multer({ storage: multer.memoryStorage() });

app.post("/convert", upload.single("file"), async (req, res) => {
  if (!req.file) return;
  const pdfBuffer = req.file.buffer;
  const pngPages = await pdfToPng(pdfBuffer, {
    viewportScale: 1.0,
    pages: [1],
  });
  res.setHeader("Content-Type", "image/png");
  res.send(pngPages[0].content);
});

app.listen(8080, '0.0.0.0');

const express = require("express");

const multer = require("multer");

const { pdfToPng } = require("pdf-to-png-converter");

const app = express();

const upload = multer({ storage: multer.memoryStorage() });

app.post("/convert", upload.single("file"), async (req, res) => {

if (!req.file) return;

const pdfBuffer = req.file.buffer;

const pngPages = await pdfToPng(pdfBuffer, {

viewportScale: 1.0,

pages: [1],

});

res.setHeader("Content-Type", "image/png");

res.send(pngPages[0].content);

});

app.listen(8080, '0.0.0.0');

package.json

{
  "name": "pdf-to-png",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "dependencies": {
    "express": "^4.18.2",
    "multer": "^1.4.5-lts.1",
    "pdf-to-png-converter": "^3.6.3"
  }
}

{

"name": "pdf-to-png",

"version": "1.0.0",

"main": "index.js",

"scripts": {

"start": "node index.js"

"dependencies": {

"express": "^4.18.2",

"multer": "^1.4.5-lts.1",

"pdf-to-png-converter": "^3.6.3"

}

GAS(時間トリガーで実行)

let mattermostUrl = "https://xxx";
let token = "xxx";
let channelId = "xxx";
let folderId = "xxx";
let folder = DriveApp.getFolderById(folderId);
let pdf2png = "https://xxx.run.app/convert";

function Main() {
  let threads = GmailApp.search("is:unread label:inbox subject:Attached Image");
  for (let i = 0; i < threads.length; i++) {
    let messages = threads[i].getMessages();
    for (let j = 0; j < messages.length; j++) {
      let message = messages[j];
      if (message.isUnread()){
        let attachments = message.getAttachments();
        if (attachments.length > 0){
          let attachment = attachments[0];
          if (attachment.getContentType() == "application/pdf") {
            CreatePng(attachment);
          }
        }
        message.markRead();
      }
    }
  }
}

function CreatePng(attachment){
  let file = folder.createFile(attachment);
  file.setName(attachment.getName());
  let fileUrl = file.getUrl();
  let formData = {
    file: file.getBlob()
  };
  const options = {
    method: "post",
    payload: formData,
    muteHttpExceptions: true
  };
  let response = UrlFetchApp.fetch(pdf2png, options);
  let responseCode = response.getResponseCode();
  if (responseCode == 200){
    let png = response.getBlob();
    PngUploadToMattermost(png,fileUrl)
  }
}

function PngUploadToMattermost(attachment,fileUrl) {
  let formData = {
    files: attachment
  }
  let endpoint = `${mattermostUrl}/api/v4/files?channel_id=${channelId}`;
  let options = {
    method: "post",
    headers: {
      Authorization: `Bearer ${token}`,
    },
    payload: formData,
    muteHttpExceptions: true,
  };
  let res = UrlFetchApp.fetch(endpoint, options);
  PostToMattermost(res,fileUrl);
}

function PostToMattermost(res,fileUrl){
  let info = JSON.parse(res.getContentText());
  let fileId = info.file_infos[0].id;
  let endpoint = `${mattermostUrl}/api/v4/posts`;
  let payload = {
    channel_id: channelId,
    message: `[![PDF](${mattermostUrl}/api/v4/files/${fileId})](${fileUrl})`
  }
  let options = {
    method: "post",
    headers: {
      Authorization: `Bearer ${token}`,
    },
    payload: JSON.stringify(payload),
    muteHttpExceptions: true,
  };
  UrlFetchApp.fetch(endpoint, options);
}

let mattermostUrl = "https://xxx";

let token = "xxx";

let channelId = "xxx";

let folderId = "xxx";

let folder = DriveApp.getFolderById(folderId);

let pdf2png = "https://xxx.run.app/convert";

function Main() {

let threads = GmailApp.search("is:unread label:inbox subject:Attached Image");

for (let i = 0; i < threads.length; i++) {

let messages = threads[i].getMessages();

for (let j = 0; j < messages.length; j++) {

let message = messages[j];

if (message.isUnread()){

let attachments = message.getAttachments();

if (attachments.length > 0){

let attachment = attachments[0];

if (attachment.getContentType() == "application/pdf") {

CreatePng(attachment);

}

message.markRead();

}

function CreatePng(attachment){

let file = folder.createFile(attachment);

file.setName(attachment.getName());

let fileUrl = file.getUrl();

let formData = {

file: file.getBlob()

};

const options = {

method: "post",

payload: formData,

muteHttpExceptions: true

};

let response = UrlFetchApp.fetch(pdf2png, options);

let responseCode = response.getResponseCode();

if (responseCode == 200){

let png = response.getBlob();

PngUploadToMattermost(png,fileUrl)

}

function PngUploadToMattermost(attachment,fileUrl) {

let formData = {

files: attachment

}

let endpoint = `${mattermostUrl}/api/v4/files?channel_id=${channelId}`;

let options = {

method: "post",

headers: {

Authorization: `Bearer ${token}`,

payload: formData,

muteHttpExceptions: true,

};

let res = UrlFetchApp.fetch(endpoint, options);

PostToMattermost(res,fileUrl);

}

function PostToMattermost(res,fileUrl){

let info = JSON.parse(res.getContentText());

let fileId = info.file_infos[0].id;

let endpoint = `${mattermostUrl}/api/v4/posts`;

let payload = {

channel_id: channelId,

message: `[![PDF](${mattermostUrl}/api/v4/files/${fileId})](${fileUrl})`

}

let options = {

method: "post",

headers: {

Authorization: `Bearer ${token}`,

payload: JSON.stringify(payload),

muteHttpExceptions: true,

};

UrlFetchApp.fetch(endpoint, options);

}