# Our app on Swarm

In this part, we will:

- **build** images for our app,

- **ship** these images with a registry,

- **run** services using these images.

---

## Why do we need to ship our images?

- When we do `docker-compose up`, images are built for our services

- These images are present only on the local node

- We need these images to be distributed on the whole Swarm

- The easiest way to achieve that is to use a Docker registry

- Once our images are on a registry, we can reference them when
  creating our services

---

class: extra-details

## Build, ship, and run, for a single service

If we had only one service (built from a `Dockerfile` in the
current directory), our workflow could look like this:

```
docker build -t jpetazzo/doublerainbow:v0.1 .
docker push jpetazzo/doublerainbow:v0.1
docker service create jpetazzo/doublerainbow:v0.1
```

We just have to adapt this to our application, which has 4 services!

---

## The plan

- Build on our local node (`node1`)

- Tag images so that they are named `localhost:5000/servicename`

- Upload them to a registry

- Create services using the images

---

## Which registry do we want to use?

.small[

- **Docker Hub**

  - hosted by Docker Inc.
  - requires an account (free, no credit card needed)
  - images will be public (unless you pay)
  - located in AWS EC2 us-east-1

- **Docker Trusted Registry**

  - self-hosted commercial product
  - requires a subscription (free 30-day trial available)
  - images can be public or private
  - located wherever you want

- **Docker open source registry**

  - self-hosted barebones repository hosting
  - doesn't require anything
  - doesn't come with anything either
  - located wherever you want

]

---

class: extra-details

## Using Docker Hub

*If we wanted to use the Docker Hub...*

- We would log into the Docker Hub:
  ```bash
  docker login
  ```

- And in the following slides, we would use our Docker Hub login
  (e.g. `jpetazzo`) instead of the registry address (i.e. `127.0.0.1:5000`)

---

class: extra-details

## Using Docker Trusted Registry

*If we wanted to use DTR, we would...*

- Make sure we have a Docker Hub account

- [Activate a Docker Datacenter subscription](
  https://hub.docker.com/enterprise/trial/)

- Install DTR on our machines

- Use `dtraddress:port/user` instead of the registry address

*This is out of the scope of this workshop!*
