1. Introduction

In this tutorial, we'll learn how to deploy services to Docker Swarm nodes. A service in Docker Swarm is a definition of tasks to be executed on the worker nodes. You'll understand how to define a service's desired state and how Docker Swarm maintains it over time.

By the end of this tutorial, you'll know how to:
- Set up a Docker Swarm
- Create and deploy services to Swarm nodes
- Scale services in Docker Swarm

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

2. Step-by-Step Guide

Docker Swarm is a tool that allows IT administrators and developers to create and manage a swarm of Docker nodes. A service is a description of a set of tasks that should be executed on the worker nodes in a swarm.

2.1 Setting up a Docker Swarm

First, initiate a Docker Swarm on your machine. Use the command docker swarm init to make your current machine a Docker Swarm manager.

$ docker swarm init

2.2 Creating a Service

To create a service, use the docker service create command followed by the image name.

$ docker service create --name my-service alpine ping google.com

Here, we created a service named 'my-service' using the 'alpine' image to ping google.com.

2.3 Deploying a Service

To deploy the service to the Docker Swarm, use the docker service ls command to list the services.

$ docker service ls

2.4 Scaling a Service

To scale a service up or down, use the docker service scale command followed by the service name and the number of replicas.

$ docker service scale my-service=5

3. Code Examples

Here are some examples of commands you might use when working with services in Docker Swarm.

3.1 Creating a Service

# Create a service named 'web-service' using the 'nginx' image
$ docker service create --name web-service nginx

This command will create a new service called 'web-service' that uses the 'nginx' image.

3.2 Scaling a Service

# Scale the 'web-service' to 3 replicas
$ docker service scale web-service=3

This command will scale the 'web-service' service to 3 replicas, meaning there will be 3 instances of this service running across your swarm.

4. Summary

In this tutorial, we learned how to set up a Docker Swarm, create and deploy services to the Swarm nodes, and scale these services.

From here, you can explore more about how to maintain the state of these services, how to update the services without any downtime, and how to manage the Swarm nodes.

5. Practice Exercises

Here are some exercises to help you practice deploying services to Docker Swarm nodes.

1. Create a service using the 'httpd' (Apache HTTP Server) image and name it 'http-service'.
2. Scale the 'http-service' to 5 replicas.
3. List all the services in your Docker Swarm.

Solution:

1. Create a service:

$ docker service create --name http-service httpd

1. Scale the service:

$ docker service scale http-service=5

1. List all services:

$ docker service ls

These exercises should give you a good understanding of how to deploy services to Docker Swarm nodes. From here, you can try deploying different services and managing more complex swarms.