Introduction to Docker Services

Create a simple service running the nginx image.
```
docker service create nginx
```
Create an nginx service with a specified name, multiple replicas, and a published port.
```
docker service create --name nginx --replicas 3 -p 8080:80 nginx
```

Use a template to pass the node hostname to each container as an environment variable.

docker service create --name node-hostname --replicas 3 --env NODE_HOSTNAME="{{.Node.Hostname}}" nginx

Get the container running on the current machine, and print its environment variables to verify that the NODE_HOSTNAME variable is set properly.
```
docker ps
docker exec <CONTAINER_ID> printenv
```
List the services in the cluster.
```
docker service ls
```
List the tasks for a service.
```
docker service ps nginx
```

Inspect a service.

docker service inspect nginx
docker service inspect --pretty nginx

Change a service.

docker service update --replicas 2 nginx

Create a global service.

docker service create --name nginx --mode global nginx

Two different ways to scale a service:

docker service update --replicas 3 nginx
docker service scale nginx=4