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)

複合機が受信したFAXをMattermostに転送してみる実験。

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表示は必須であり､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);

}

※追記
Markdownの画像リンクはモバイルアプリで表示されないという不具合があるようだったのでfile_idsに変更。

function PostToMattermost(res,fileUrl){
  let info = JSON.parse(res.getContentText());
  let fileId = info.file_infos[0].id;
  let endpoint = `${mattermostUrl}/api/v4/posts`;
  let payload = {
    channel_id: channelId,
    file_ids: [fileId],
    message: "---  \n" + `[PDFを開く](${fileUrl})`,
  }
  let options = {
    method: "post",
    headers: {
      Authorization: `Bearer ${token}`,
      "Content-Type": "application/json",
    },
    payload: JSON.stringify(payload),
    muteHttpExceptions: true,
  };
  UrlFetchApp.fetch(endpoint, options);
}

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,

file_ids: [fileId],

message: "--- \n" + `[PDFを開く](${fileUrl})`,

}

let options = {

method: "post",

headers: {

Authorization: `Bearer ${token}`,

"Content-Type": "application/json",

payload: JSON.stringify(payload),

muteHttpExceptions: true,

};

UrlFetchApp.fetch(endpoint, options);

}