Nodemon doesn't reload in docker container when files change - node.js

Question

I read many threads sabout this but no one solves anything.
Some say you have to add --legacy-watch (or -L) to the nodemon command.
Others shows several different configurations and apparently nodody really knows what you gotta do to achieve server restarting when a file change at the volume inside a docker container.
Here my configuration so far:
Dockerfile:
FROM node:latest
# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
# install nodemon globally
RUN npm install nodemon -g
# Install dependencies
COPY package*.json ./
RUN npm install
# Bundle app source
COPY . /usr/src/app
# Exports
EXPOSE 3000
CMD ["npm", "start"]
docker-compose.yml
version: '3.1'
services:
node:
build: .
user: "node"
volumes:
- ./:/usr/src/app
ports:
- 3000:3000
depends_on:
- mongo
working_dir: /usr/src/app
environment:
- NODE_ENV=production
expose:
- "3000"
mongo:
image: mongo
expose:
- 27017
volumes:
- ./data/db:/data/db
environment:
MONGO_INITDB_ROOT_USERNAME: root
MONGO_INITDB_ROOT_PASSWORD: example
package.json
{
"name": "node-playground",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "nodemon -L"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"ejs": "^2.7.1",
"express": "^4.17.1",
"mongoose": "^5.7.1"
},
"devDependencies": {
"nodemon": "^1.19.2"
}
}
I tried many different setups as well. Like not installing globally nodemon but only as a project dependency. And also running the command at the docker-compse.yml, and i believe many others I don't remember right now. Nothing.
If someone has any cetainty about this, please help. Thanks!!!!

Answer 1

Try it!
This worked for me:
Via the CLI, use either --legacy-watch or -L for short. More informations here.

Answer 2

I went ahead and created an example container and repo to show how you can achieve this..
Just follow the steps below, which outline how to use nodemon inside of a Docker container.
Docker Container: at DockerHub
Source Code: at GitHub
package.json:
{
"name": "nodemon-docker-test",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start:express": "node ./index.js",
"start": "nodemon"
},
"author": "",
"license": "ISC",
"dependencies": {
"express": "^4.17.1"
},
"devDependencies": {
"nodemon": "^1.19.2"
}
}
Dockerfile:
FROM node:slim
WORKDIR /app
COPY package*.json ./
RUN apt-get update
RUN npm install
COPY . /app
# -or-
# COPY . .
EXPOSE 1337
CMD ["npm", "start"]
docker-compose.yml: (if you are using it)
version: "3"
services:
nodemon-test:
image: oze4/nodemon-docker-test
ports:
- "1337:1337"
How to reproduce:
Step 1 USING DOCKER RUN: SKIP IF YOU ARE USING DOCKER COMPOSE (go to step 1 below if you are) pull down example docker container
docker run -d --name "nodemon-test" -p 1337:1337 oze4/nodemon-docker-test
Step 1 USING DOCKER-COMPOSE:
See the docker-compose.yml file above for configuration
cd /path/to/dir/that/has/your/compose/file
docker-compose up -d
Step 2: verify the app works
http://localhost:1337
Step 3: check the container logs, to get a baseline
docker logs nodemon-test
Step 4: I have included a bash script to make editing a file as simple as possible. We need to pop a shell on the container, and run the bash script (change.sh)
docker exec -it nodemon-test /bin/bash
bash change.sh
exit
Step 5: check the logs again to verify changes were made and that nodemon restarted
docker logs nodemon-test
As you can see by the last screenshot, nodemon successfully restarted after changes were made!

Answer 3

All right
Thanks a lot to MattOestreich for your answer.
Now i got it working, I don't know what it was, i did follow your set up but of course i'm using docker-compose and i also stripped some things out of it. I'm also not calling mongo image anymore since i setup the db in an Mongodb atlas cluster.
my actual config:
Dockerfile:
FROM node:12.10
WORKDIR /app
COPY package*.json ./
RUN apt-get update
RUN npm install
COPY . /app
EXPOSE 3000
CMD ["npm", "start"]
docker-compse.yml
version: '3.1'
services:
node:
build: .
volumes:
- ./:/app
ports:
- 3000:3000
working_dir: /app
expose:
- "3000"
package.json
{
"name": "node-playground",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "nodemon"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"body-parser": "^1.19.0",
"dotenv": "^8.1.0",
"ejs": "^2.7.1",
"express": "^4.17.1",
"mongoose": "^5.7.1"
},
"devDependencies": {
"nodemon": "^1.19.2"
}
}
thanks Matt again and i hope this thread helps people in need like me.

Answer 4

Nodemon depends on Chokidar and a potential solution is to make it use polling by setting CHOKIDAR_USEPOLLING environment variable to true.
For example you can do this in docker-compose.yml:
services:
api1:
build:
context: .
dockerfile: Dockerfile
volumes:
- /app/node_modules
- ${PWD}:/app
ports:
- 80:3000
environment:
- CHOKIDAR_USEPOLLING=true

Answer 5

Change in Docker file
CMD ["npm", "start"]
Change start script
"start": "nodemon -L server.js"
Build Command
docker build . -t <containername>
Use this command to run the docker container
docker run -v $(pwd):/app -p 8080:8080 -it <container Id>
-v = Volumes . the preferred mechanism for persisting data generated by and used by Docker containers.
/app = WORKDIR /app
$(pwd) = PWD is a variable set to the present working directory. So $(pwd) gets the value of the present working directory