So I'm learning Docker and how to containerize apps into services. Not sure if I get it all the way.
I have three services:
web-servernginx server that binds ports 80 and 443 to outside. Basically the "frontend" of the app.app1NodeJS app that serves content on port 3000app2NodeJS app that serves content on port 3000, basically it's a clone ofapp1and I use it just for learning purposes.
Now my idea of running this "app" in prod would be to launch docker-compose up which launches all the services. Is this a correct way to launch multi container apps?
My repo structure is this:
.
├── Dockerfile
├── app1
│ ├── Dockerfile
│ ├── index.js
│ ├── package-lock.json
│ └── package.json
├── app2
│ ├── Dockerfile
│ ├── index.js
│ ├── package-lock.json
│ └── package.json
├── docker-compose.yml
├── index.html
└── web-server.conf
The root Dockerfile is for web-server service. My docker-compose.yml looks like this:
version: '3'
services:
web-server:
container_name: web-server
build: .
ports:
- "80:80"
- "443:443"
depends_on:
- app1
- app2
app1:
container_name: app1
build: ./app1
restart: always
app2:
container_name: app2
build: ./app2
restart: always
The command docker-compose up builds app1 and app2 images, however it fails on web-server image because nginx throws an error:
host not found in upstream "app1" in /etc/nginx/conf.d/default.conf:11
nginx: [emerg] host not found in upstream "app1" in /etc/nginx/conf.d/default.conf:11
web-server service Dockerfile
FROM nginx:alpine
EXPOSE 80
COPY ./web-server.conf /etc/nginx/conf.d/default.conf
COPY ./index.html /var/www/html/
RUN apk add bash
RUN nginx
Contents of web-server.conf:
server {
listen *:80;
server_name web_server;
root /var/www/html;
location / {
index index.html;
}
location /app1 {
proxy_pass http://app1:3000;
proxy_redirect off;
}
location /app2 {
proxy_pass http://app2:3000;
proxy_redirect off;
}
}
To me it looks like the config for nginx won't recognize http://app1 hostname at the build time. I tried experimenting and I replaced the values for proxy_pass directives with localhost. This will build the image which I can run along with other images. If I do bundle exec -it web-server-image /bin/bash and I try curl http://app1:3000 then it works. If I edit the nginx config to point to these URLs it starts to work.
So I think I'm getting there but it seems it won't recognize the host names when running docker-compose up.
Any ideas? Is my approach correct?
