Memory resources for a docker container running from docker-compose - docker

Question

I’m running Sonarqube on Docker compose and my file looks like this:
version: "3"
services:
sonarqube:
image: sonarqube
ports:
- "9000:9000"
- "5432:5432"
links:
- db:db
environment:
- SONARQUBE_JDBC_URL=jdbc:postgresql://db:5432/sonar
- SONARQUBE_JDBC_USERNAME=postgres
- SONARQUBE_JDBC_PASSWORD=sonar
volumes:
- ..../Work/tools/_SonarQube_home/conf:/opt/sonarqube/conf
# - sonarqube_data:/opt/sonarqube_new/data
- ...../Work/tools/_SonarQube_home/data:/opt/sonarqube/data
- ....../Work/tools/_SonarQube_home/extensions:/opt/sonarqube/extensions
- ..../Work/tools/_SonarQube_home/bundled-plugins:/opt/sonarqube/lib/bundled-plugins
db:
image: postgres
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=sonar
- POSTGRES_DB=sonar
volumes:
- .../Work/tools/_PostgreSQL_data:/var/lib/postgresql
# This needs explicit mapping due to https://github.com/docker-library/postgres/blob/4e48e3228a30763913ece952c611e5e9b95c8759/Dockerfile.template#L52
- ..../Work/tools/_PostgreSQL_data/data:/var/lib/postgresql/data
Everything works and that’s great. One moment I saw that Sonarqube instance started to act slowly, therefore I checked docker stats. It looks like this:
| CPU | Mem Usage/ Limit |
|-------| --------------------
| 5.39% | 1.6GiB / 1.952GiB |
How do I define more RAM resources for the server, let’s say 4 GB? Previously it was mem_limit but now on version 3 it doesn’t exist.
What would be a good solution for that?
Thanks!

Answer 1

If you are deploying to Swarm, then you can use the resources keyword in your Compose file. (it's described under Resources in the file reference https://docs.docker.com/compose/compose-file/)
So you can do something like this is Swarm:
version: "3.7"
services:
redis:
image: redis:alpine
deploy:
resources:
limits:
cpus: '0.50'
memory: 50M
reservations:
cpus: '0.25'
memory: 20M
If you are using Compose, then you have the option to go back to Compose file version 2.0, as described in the Compose file reference by Docker.
Looking for options to set resources on non swarm mode containers?
The options described here are specific to the deploy key and swarm mode. If you want to set resource constraints on non swarm
deployments, use Compose file format version 2 CPU, memory, and other
resource options. If you have further questions, refer to the
discussion on the GitHub issue docker/compose/4513.
I'm not familiar with Sonarqube memory issue, but you may want to have a look at this https://docs.sonarqube.org/display/SONARqube71/Java+Process+Memory.

Answer 2

In Compose file version 3, resource limits moved to under a deploy: {resources: ...} key, but are also only documented to work in Swarm mode. So to actually set them you need to switch to a mostly-compatible version 2 Compose file.
version: '2'
services:
sonarqube:
mem_limit: 4g
The default should be for the container to be able to use an unlimited amount of memory. If you're running in an environment where Docker is inside a Linux VM (anything based on Docker Toolbox or Docker Machine, Docker for Mac) it's limited by the memory size of the VM.