[Node.js & Docker] node-cronをDockerコンテナから使ってスケジュール実行をさせてみる

            
            $ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 10 (buster)
Release: 10
Codename: buster
$ docker -v
Docker version 19.03.8, build afacb8b7f0
$ docker-compose -v
docker-compose version 1.16.1, build 6d1ac21
        

            
            $ touch Dockerfile docker-compose.yml index.js package.json && mkdir tmp
$ tree
.
├── Dockerfile
├── docker-compose.yml
├── index.js
├── package.json
└── tmp #👈空のフォルダ
        

            
            FROM node:12-alpine
ENV NODE_ENV development
WORKDIR /usr/src/app

COPY package.json ./

RUN yarn install && yarn cache clean

CMD ["node", "index.js"]
        

            
            version: '3'

services:
  cron:
    image: node-cron-dckr:12-alpine
    build: .
    container_name: my-node-cron
    user: 'node:node'
    environment:
      NODE_ENV: development
    volumes:
        - ./:/usr/src/app
    tty: true
        

            
            const cron = require('node-cron');
const fs = require("fs");

cron.schedule('* * * * *', () => {
    try{
        console.log('running a task every minute');
        fs.appendFileSync("tmp/file.txt", "Hello Node-Cron!\n");
    }
    catch(e){
        console.log(e.message);
    }
});
        

            
            {
    "name": "node-cron-dckr",
    "version": "0.0.1",
    "devDependencies": {
        "node-cron": "^2.0.0"
    }
}
        

            
            $ docker-compose build
$ docker images
REPOSITORY       TAG         IMAGE ID      SIZE
node-cron-dckr   12-alpine   76bed01fec57  104MB
        

            
            Example of job definition:
　.---------------- minute (0 - 59)
　|  .------------- hour (0 - 23)
　|  |  .---------- day of month (1 - 31)
　|  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
　|  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
　|  |  |  |  |
　*  *  *  *  * user-name command to be executed
        

            
            * * * * 1:
    月曜日限定で毎分実行
10 * * * *:
    毎時間、時計の針が10分になったら実行
    (..., 8:10, 9:10, 10:10, ...)
20 8 * * *:
    毎日午前8時20分になったら実行
        

            
            $ docker-compose run -d cron
        

            
            $ cat tmp/file.txt
Hello Node-Cron!
Hello Node-Cron!
Hello Node-Cron!
Hello Node-Cron!
#...以降一分毎に更新
        

            
            $ docker ps
CONTAINER ID        IMAGE                      COMMAND                  STATUS   NAMES
0639a40822ed        node-cron-dckr:12-alpine   "docker-entrypoint.s…"  Up       nodecrondckr_cron_run_1
        

            
            #👇コンテナを止める場合
$ docker stop nodecrondckr_cron_run_1
nodecrondckr_cron_run_1
#👇コンテナを消す場合
$ docker rm nodecrondckr_cron_run_1
nodecrondckr_cron_run_1