How to run Sequelize migrations inside Docker

Question

I'm trying to docerize my NodeJS API together with a MySQL image. Before the initial run, I want to run Sequelize migrations and seeds to have the tables up and ready to be served.

Here's my docker-compose.yaml:

version: '3.8'
services: 
  mysqldb:
    image: mysql
    restart: unless-stopped
    environment:
      MYSQL_ROOT_USER: myuser
      MYSQL_ROOT_PASSWORD: mypassword
      MYSQL_DATABASE: mydb
    ports:
      - '3306:3306'
    networks:
      - app-connect
    volumes: 
      - db-config:/etc/mysql
      - db-data:/var/lib/mysql
      - ./db/backup/files/:/data_backup/data
  app:
    build:
      context: .
      dockerfile: ./Dockerfile
    image: node-mysql-app
    depends_on:
      - mysqldb
    ports:
      - '3030:3030'
    networks:
      - app-connect
    stdin_open: true
    tty: true
volumes: 
  db-config:
  db-data:
networks:
  app-connect:
      driver: bridge

Here's my app's Dockerfile:

FROM node:lts-alpine
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 3030
ENV PORT 3030
ENV NODE_ENV docker
RUN npm run db:migrate:up
RUN npm run db:seeds:up
CMD [ "npm", "start" ]

And here's my default.db.json that the Sequelize migration uses (shortened):

{
  "development": {
    
  },
  "production": {
    
  },
  "docker": {
    "username": "myuser",
    "password": "mypassword",
    "database": "mydb",
    "host": "mysqldb",
    "port": "3306",
    "dialect": "mysql"
  }
}

Upon running compose up the DB installs well, the image deploys, but when it reaches the RUN npm run db:migrate:up (which translates into npx sequelize-cli db:migrate) I get the error:

npx: installed 81 in 13.108s

Sequelize CLI [Node: 14.17.0, CLI: 6.2.0, ORM: 6.6.2]

Loaded configuration file "default.db.json".
Using environment "docker".


ERROR: getaddrinfo EAI_AGAIN mysqldb
npm ERR! code ELIFECYCLE
npm ERR! errno 1

If I change the "host" in the default.db.json to "127.0.0.1", I get ERROR: connect ECONNREFUSED 127.0.0.1:3306 in place of the ERROR: getaddrinfo EAI_AGAIN mysqldb.

What am i doing wrong, and what host should I specify so the app can see the MySQL container? Should I remove the network? Should I change ports? (I tried combinations of both to no avail, so far).

Answer 1

I solved my issue by using Docker Compose Wait. Essentially, it adds a wait loop that samples the DB container, and only when it's up, runs migrations and seeds the DB.

My next problem was: those seeds ran every time the container was run - I solved that by instead running a script that runs the seeds, and touchs a semaphore file. If the file exists already, it skips the seeds.

Answer 2

I found a really clean solution wanted to share it. First of all I used docker-compose, so if you are using only docker, it might not help. First thig first, I created a docker file which looks like that.I am using typescript, so if you are using js, you don't need to download typescript and build it!

FROM node:current-alpine
WORKDIR /app
COPY . ./
COPY .env.development ./.env


RUN npm install
RUN npm install -g typescript

RUN npm install -g sequelize-cli
RUN npm install -g nodemon

RUN npm run build
RUN rm -f .npmrc

RUN cp -R res/ dist/
RUN chmod 755 docker/entrypoint.sh
EXPOSE 8000

EXPOSE 3000
EXPOSE 9229
CMD ["sh", "-c","--","echo 'started';while true; do sleep 1000; done"]

Till here it is standart. In order to do things in right order, I need a docker compose and entrypoint file. Entrypoint file is a file, that runs when your containers start. Here is docker-compose file.

version: '3'

services:
  app:
    build:
      context: ..
      dockerfile: docker/Dockerfile.development
    entrypoint: docker/development-entrypoint.sh
    ports:
      - 3000:3000
    env_file:
      - ../.env.development
    depends_on:
      - postgres
      
  
  postgres:
    image: postgres:alpine
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=test
    volumes:
      - ./docker_postgres_init.sql:/docker-entrypoint-initdb.d/docker_postgres_init.sql

As you can see, I am using postgresql for db. My docker file, docker-compose and also entrypoint files are in a folder called docker, thats why the paths starts wtih docker, change it according to your file structure. Last and the best part is the entrypoint file. It is really simple.

#!/bin/sh

echo "Starting get ready!!!"
sequelize db:migrate
nodemon ./dist/index.js

Ofcourse change the path of the index.js file according to your settings. Hope it helps!