Skipper

Build, deploy and orchestrate your application using Docker.

Quick start

With skipper installed, let's deploy a simple web app.

In the app's directory, let's define a skipper.yml.

It describers...

• services - the Docker containers that comprise our app.
• groups - the instances that comprise our cluster.
• name - the name of our application
• region - the region our cluster runs on.

skipper.yml

name: "demo"
services:
    web:
        build: .
        scale: 1 # Optional, by default 1.
        ports:
            - "80:5000"
        repo:
            name: "cameronmaske/flask-web"
region: "us-east-1"
groups:
    web:
        size: "t1.micro"
        ports:
            public:
                - "80"
        services:
            - web

Now, let's create web app powered by Flask (A python micro framework) with a Dockerfile that runs it.

app.py

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World! v1"

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=5000)

Dockerfile

FROM python:2.7
ADD . /code
WORKDIR /code
RUN pip install Flask
ADD app.py app.py
CMD python app.py

Now using skipper, we can deploy our service across the cluster. Deployments using skipper are comprised of three steps...

• tag - Build the service Docker image with an assigned tag.
• push - Uploads the tagged image to a Docker image registry.
• deploy - Coordinates with the desired host (currently only AWS is supported) to launch or retrieve the required instances, and run the desired services.

When using skipper on a new project, you will be prompted for a various credentials required to communicate with the host (such as public/private ssh keys, or access/secret tokens). These are stored in a .skippercfg file, which should not be checked in too any source control.

$ skipper tag web:v1
Building web...
 ---> cdc18ed4ed6f
Step 1 : ADD . /code
 ---> a8bf1d374c29
Removing intermediate
...
Successfully built web...
$ skipper push web:v1
Sending image list
Pushing repository cameronmaske/flask-web (1 tags)
Pushing
Image already pushed, skipping
....
Image successfully pushed
Pushing tag for rev [e5bf1196d912] on {https://cdn-registry-1.docker.io/v1/repositories/cameronmaske/flask-web/tags/v1}
$ skipper deploy web:v1
Checking for instance [web_1].

As this is your first time running skipper, we need to store your some AWS Security Credentials.
Please visit https://console.aws.amazon.com/iam/home?#security_credential
Under Access Keys, click Create New Access Key.
Enter your Access Key ID: BCDHTEJEETTTRACEZ3GHQ
Enter your Secret Access Key: TC9hCTrsOWmLTAHECAGE192831BpPOd1lm90

Failed to find instance [web_1].

A KeyPair, consisting of an SSH public and private key is required for access to the cluster.
Please enter the an existing KeyPair's name, or enter a unique name for yourself: MyKeyPair
Please enter the path to a SSH public key: ~/.ssh/skipper.pub
Please enter the path to a SSH private key: ~/.ssh/skipper

Starting a new instance [web_1].

No token set for your etcd cluster.
Please visit https://discovery.etcd.io/new to generate a new one, or enter your existing one: https://discovery.etcd.io/49581751507f299928a34c8737f12

Successfully created instance [web_1].
Checking for service [web_1] on instance [web_1].
No existing service [web_1] found.
Creating service [web_1].
Successfully created service [web_1].
Deployment was successful.

Next we can check the app is running as expected.

$ skipper ps
+-------+---------+----------+---------------+---------+-------+
| uuid  |  state  | instance |      ip       | service | scale |
+-------+---------+----------+---------------+---------+-------+
| web_1 | running | web_1    | 54.165.238.25 | web     | 1     |
+-------+---------+----------+---------------+---------+-------+
$ curl 54.165.238.25
Hello World! v1

To ship a new version, we once again follow the three steps of tag, push and deploy.

$ # Replace v1 with v2.
$ sed -i -e 's/v1/v2/g' app.py
$ cat app.py | grep Hello World
    return "Hello World! v2"
$ skipper tag web:v2
$ skipper push web:v2
$ skipper deploy web:v2
$ curl 54.165.238.25
Hello World! v2

Installation

Requires Docker to be installed.

Docker has guides for Ubuntu and other platforms in their documentation. If you're on OS X, you can use docker-osx:

Skipper can be installed as a Python package using...

$ sudo pip install -U skipper

Documentation

Skipper is built on top of Docker and CoreOS. Using CoreOS's etcd and fleet services simplifies cluster management and container orchestration. Unlike other PaaS that use Git (such as Heroku) as their mechanism to push and deploy applications, skipper moves that responsibility to Docker. Using Docker, you tag, push and deploy images across your cluster. Currently the only host supported is AWS but other host support, starting with DigitalOcean is planned.

skipper.yml

The skipper.yml contains all the information required to build, tag and deploy docker containers across your desired cluster.

name: demo
services:
    web:
        build: .
        scale: 1
        ports:
            - "80:5000"
        repo:
            name: "cameronmaske/flask-web"
region: "us-east-1"
groups:
    web:
        size: "t1.micro"
        scale: 2
        ports:
            public:
                - "80"
        services:
            - web

name (required)

Every project needs a name. This is used to identify which instances are project specific on a host.

region

region: "ap-northeast-1"
region: "us-east-1"

Which Amazon EC2 region should I launch instances on? Defaults to "us-east-1".

Only a single region is currently supported.

services

Services define the components that make up your app.

repo (required)

repo:
    name: "cameronmaske/node-app"
    registry: "index.docker.io"

Points to a repo to upload and/or pull a Docker images from. If a registry is not included, defaults to the official Docker Hub Registry.

Currently only public registries are supported.

build

build: folder/another/web
build: .

Path to a directory containing a Dockerfile to build the image off.

scale

scale: 1
scale: 10

Determines how many containers should be run for each service on each desired instance.

ports

ports:
    - "80:5000"
    - "80"

Exposes ports on a service's containers. Takes the format of HOST:CONTAINER. Either specify both ports, or just a container port (the host port is chosen at random).

groups

Groups define the instances that make up your cluster.

size

size: "t1.micro"
size: "m2.2xlarge"

What AWS EC2 instance type should be used for instances belonging to this group?

ports

ports:
    public:
        - "80"
        - "443"

What ports should be exposed publicly?

services

services:
    - redis
    - web

What services should run on instances associated with the group?

scale

scale: 1
scale: 10

How many instances are required to make up the group?

.skippercfg

Stores sensitive data required for skipper, such as AWS credentials. Make sure this is not publicly exposed

CLI

Each of skipper's commands can be run with --help to reveal more information about what they do.

$ skipper --help
Usage: skipper [OPTIONS] COMMAND [ARGS]...

  A docker orchestration tool that allows you to easily
  deploy and manage your applications.

Options:
  --silent   Suppress logging messages.
  --version  Show the version and exit.
  --help     Show this message and exit.

Commands:
  clean      Removes older images locally for a services.
  deploy     Deploy services across the cluster.
  instances  Manages instances.
  ps         List all services running across the cluster.
  push       Push tagged services to their registries.
  remove     Remove a running service by uuid.
  tag        Build and tag services.

Roadmap

Below is a outline of the feature set desired for 1.0.

• Better documentation .
• Environment variables (cluster wide and service specific).
• Logging.
• Linking containers.
• Linking instances privately.
• DigitalOcean Support.
• Multi region support.
• Private repo support.
• Team and multiple user support.

Inspiration

Heavily inspired by Fig and head-in-the-clouds.

Contact

For bugs, please open an issue on GitHub. If you have any comments, thoughts or ideas for skipper, feel free to also open an issue, tweet me or drop me an email.