1. Introduction

In this tutorial, we will learn how to monitor and manage Docker Swarm services. Docker Swarm is a clustering and scheduling tool for Docker containers. With Docker Swarm, IT administrators and developers can establish and manage a cluster of Docker nodes as a single virtual system.

You'll learn how to:
- Track the performance of your Docker Swarm services
- Manage the health of these services
- Control the resources effectively for optimal performance

Prerequisites:
- Basic knowledge of Docker and Docker Swarm
- Docker and Docker Swarm installed on your system

2. Step-by-Step Guide

Docker Service Commands

In Docker Swarm, services are the primary operational component. They are the "tasks" that the swarm manager assigns to the worker nodes. To manage these services effectively, there are several Docker service commands:

• docker service create: Create a new service
• docker service inspect: Display detailed information on one or more services
• docker service ls: List services
• docker service rm: Remove one or more services
• docker service scale: Scale one or multiple replicated services
• docker service ps: List the tasks of one or more services
• docker service update: Update a service

Monitoring Docker Swarm

Docker provides built-in mechanisms to monitor the performance of your Swarm. The docker stats command gives a live data stream for all containers running on a container's host.

docker stats

Tip: For a more in-depth view, there are third-party tools like cAdvisor, Prometheus, or Datadog.

3. Code Examples

Create a Service

Here is an example of how to create a service:

docker service create --name my_web nginx:latest

In this command:
- docker service create initiates the creation of a new service.
- --name my_web assigns the name "my_web" to the new service.
- nginx:latest is the image that the service will run.

Scale a Service

To scale your service, use the docker service scale command:

docker service scale my_web=3

This command scales the "my_web" service to have three replicas.

Update a Service

To update your service, use the docker service update command:

docker service update --image nginx:1.19 my_web

This command updates the "my_web" service to use the nginx:1.19 image.

4. Summary

In this tutorial, we have covered how to monitor and manage Docker Swarm services. We've learned how to create, scale, and update services, and how to monitor their performance.

Next steps for learning include exploring third-party tools for more detailed monitoring and learning how to manage Docker Swarm nodes.

Some additional resources for further learning include:
- The official Docker documentation (https://docs.docker.com/)
- Docker Mastery: The Complete Toolset From a Docker Captain course on Udemy

5. Practice Exercises

1. Create a new service named "my_api" using the "nginx:alpine" image.

2. Solution: docker service create --name my_api nginx:alpine

3. Scale the "my_api" service to have five replicas.

4. Solution: docker service scale my_api=5

5. Update the "my_api" service to use the "nginx:1.18" image.

6. Solution: docker service update --image nginx:1.18 my_api

Remember to keep practicing and experimenting with different commands and options to further your understanding of Docker Swarm management.