Upgrade docker-compose to version 3 - docker

Question

This is how my docker-compose.yml file looks like. As you can see, there is a nginx server, a mongoDB, the main application and for testing a nightwatch and selenium container.
nginx:
container_name: 'nginx'
image: 'nginx:1.11'
restart: 'always'
ports:
- '80:80'
- '443:443'
volumes:
- '/opt/nginx/conf.d:/etc/nginx/conf.d:ro'
- '/opt/nginx/conf/nginx.conf:/etc/nginx/nginx.conf:ro'
- '/etc/letsencrypt:/etc/letsencrypt'
- '/opt/nginx/www:/var/www:ro'
links:
- 'app'
nightwatch:
container_name: nightwatch
image: 'registry.example.com/project/core:nightwatch'
links:
- selenium
stdin_open: true
tty: true
selenium:
container_name: selenium
image: selenium/standalone-chrome
ports:
- 4444:4444
links:
- app
db:
container_name: db
image: 'mongo:3.4'
restart: 'always'
volumes:
- '/opt/mongo/project/prod:/data/db'
app:
container_name: app
image: 'registry.example.de/project/core:latest'
restart: always
links:
- 'db'
environment:
- ROOT_URL=https://example.com
- MONGO_URL=mongodb://db/db
You can also see, that I'm still using version 1 and I want to upgrade to current version (3). And there are a few problems for converting the file.
For example I do not understand the network option which should be used instead of the deprecated link to get access to containers.
In the nightwatch container I'm running a script like
module.exports = {
'start application': function(browser) {
browser
.url('http://app') // <--
.waitForElementVisible('body', 10000)
.getTitle(function(result) {
this.assert.equal(typeof result, 'string')
})
},
}
So I need to get access to the app container via nightwatch, which also needs selenium. The main app needs of course the db.
I need some help converting to version 3:
version: '3'
services:
nginx:
...
nightwatch:
...

Answer 1

This should be enough:
version: "3"
services:
nginx:
container_name: 'nginx'
image: 'nginx:1.11'
restart: 'always'
ports:
- '80:80'
- '443:443'
volumes:
- '/opt/nginx/conf.d:/etc/nginx/conf.d:ro'
- '/opt/nginx/conf/nginx.conf:/etc/nginx/nginx.conf:ro'
- '/etc/letsencrypt:/etc/letsencrypt'
- '/opt/nginx/www:/var/www:ro'
links:
- app
nightwatch:
container_name: nightwatch
image: 'registry.example.com/project/core:nightwatch'
links:
- selenium
stdin_open: true
tty: true
selenium:
container_name: selenium
image: selenium/standalone-chrome
ports:
- 4444:4444
links:
- app
db:
container_name: db
image: 'mongo:3.4'
restart: 'always'
volumes:
- '/opt/mongo/project/prod:/data/db'
app:
container_name: app
image: 'registry.example.de/project/core:latest'
restart: always
links:
- db
environment:
- ROOT_URL=https://example.com
- MONGO_URL=mongodb://db/db
You don't need to configure extra networks than the default provided by compose.
Linking containers is still configured as so. Try this:
version: "3"
services:
abc:
image: ubuntu
command: tail -f /dev/null
cde:
image: busybox
command: ping abc
links:
- abc