Memory limits and reservations in Docker - Mini Project: Build & Apply

Memory Limits and Reservations in Docker

📖 Scenario: You are managing a Docker container that runs a small web application. To keep the container stable and prevent it from using too much memory on the host machine, you want to set memory limits and reservations.This helps the container run smoothly without affecting other applications on the same server.

🎯 Goal: You will create a Docker container with specific memory limits and memory reservation settings. This will ensure the container uses memory efficiently and respects the host's resources.

📋 What You'll Learn

Create a Docker container running the nginx image

Set a memory limit of 300MB for the container

Set a memory reservation of 150MB for the container

Verify the container is running with the correct memory settings

💡 Why This Matters

🌍 Real World

Setting memory limits and reservations helps keep Docker containers from using too much memory, which can slow down or crash other applications on the same server.

💼 Career

Understanding resource limits is important for DevOps roles to ensure applications run reliably in shared environments.

1

Create a Docker container running nginx

Write the Docker command to create and run a container named mynginx using the nginx image in detached mode.

Docker

# Your code here

Need a hint?

Use docker run with -d for detached mode and --name mynginx to name the container.

2

Add a memory limit of 300MB

Modify the Docker run command to add a memory limit of 300m using the --memory option.

Docker

docker run -d --name mynginx --memory 300m nginx
# Your code here

Need a hint?

Use --memory 300m to limit the container memory to 300 megabytes.

3

Add a memory reservation of 150MB

Extend the Docker run command to include a memory reservation of 150m using the --memory-reservation option.

Docker

docker run -d --name mynginx --memory 300m --memory-reservation 150m nginx
# Your code here

Need a hint?

Use --memory-reservation 150m to set the soft memory limit to 150 megabytes.

4

Verify the container memory settings

Write the Docker command to inspect the container mynginx and display only the memory limit and memory reservation values.

Docker

docker container inspect mynginx --format '{{json .HostConfig.Memory}} {{json .HostConfig.MemoryReservation}}'
# Your code here

Need a hint?

Use docker container inspect with --format to show memory settings.