By default a Docker container, like any other system process, can use the entire available memory of the Docker host. Memory Limits and Memory Reservations are two different aspects to ensure a smooth functioning of your applications and the Docker host you are running atop.īroadly speaking, Memory Limit imposes an upper limit to the amount of memory that can potentially be used by a Docker container. This will return docker to a clean state with the exception of any volumes that were created (we didn’t create any so that’s not a concern.) Memory Limits and Memory Reservations Let’s start a simple nginx server using Docker-CLI : In the next section, we shall explore its memory limitations and utilization and modify our docker-compose.yml to see how the custom limitations are imposed. Let’s try and run a simple Nginx service on port 80 using first the CLI and then a simple docker-compose.yml. Most of the code would work just the same for version 3, and where there will be a difference, I will mention the newer syntax for Docker Swarm users. So to keep matter simple for regular Docker users I will stick to version 2.4 If you try to use the newer syntax, it insists on using Docker in Swarm mode, instead.

We could have gone with version 3 which is more recent but it doesn’t support old memory limitation syntax. We shall be sticking to the version 2.4 for our docker-compose.yml files as that supports version 17.12 and higher of Docker Engine and higher.

Docker Compose binary (Windows and Mac users will already have this installed).

Docker for Windows or Mac or if you are running Linux, DockerCE for Linux.

You’d need the following tools in your arsenal to follow along: We will be focusing on specifying memory utilization here. For example, your frontend http server will be listed as a frontend service running an Apache or an Nginx image as a container.Īll the services, their networking needs, storage requirements, etc can be specified in a docker-compose.yml file.

Each logically different workload is listed as a different service. We spin up different containers to handle different workloads of an application and we use Docker Compose for doing this easily.

Usually, it is not a great idea to run the entire stack including the frontend, the database server, etc from inside a single a single container. It saves time and reduces errors when deploying your Dockerized application.

Docker for mac general setting