Added swarm demo

This PR adds a demo with docker swarm and docker-machine.

README.md

@@ -12,9 +12,12 @@ We designed in collaboration with InfluxData to show how metrics can be used.
 It is based on plugins called `provider`. At the moment we implemented:
 
 * Docker Swarm mode [(go to zero-conf
-  chapter](https://github.com/gianarb/orbiter#autodetect)
+  chapter](https://github.com/gianarb/orbiter#autodetect). look full example
+  under `./contrib/swarm` directory
 * DigitalOcean
 
+
+
 ```sh
 orbiter daemon -config config.yml
 ```

contrib/swarm/Makefile

@@ -0,0 +1,15 @@
+IP = $(shell docker-machine ip sw1)
+init:
+	./cluster/create.sh
+destroy:
+	docker-machine rm -f sw1 sw2 sw3 sw4
+deploy:
+	docker stack deploy --compose-file stack.yml stack
+ps:
+	docker service ls
+	docker stack ps stack
+scale-up:
+	curl -X POST -v http://$(IP):8081/handle/autodetect_swarm/stack_micro/up
+scale-down:
+	curl -X POST -v http://$(IP):8081/handle/autodetect_swarm/stack_micro/down
+

contrib/swarm/README.md

@@ -0,0 +1,57 @@
+This is a tutorial to use orbiter as autoscaler with Docker Swarm.
+
+Requirements:
+
+* Docker CLI installed
+* Docker Machine
+* Virtualbox
+
+1. Create a swarm cluster with 4 nodes. One manager and three workers. It uses
+   Docker Machine and Virtualbox as provider.
+```
+make init
+```
+
+2. Point Docker CLI to the right Docker machine. The master is called sw1.
+
+```
+eval $(docker-machine env sw1)
+```
+
+3. Deploy your stack. The stack contains two services, one called orbiter and
+   another called micro. Micro is the web app that we are autoscaling.
+
+```
+make deploy
+```
+
+4. This command shows the current situation. The first table represent the
+   number of services and how many task are running under a service. You should
+   see two services. Micro has 10 tasks.
+
+```
+make ps
+```
+
+5. There is an utility in the makefile to scale up and down micro.
+
+```
+make scale-up
+make scale-down
+```
+
+6. You can check the number of tasks changing every time you scale with the
+   command:
+
+```
+make ps
+```
+
+7. At the end of the test you can clean your envrionment
+
+```
+make destroy
+```
+
+That's it. Have a look at the code in `./stack.yml` and `Makefile` to have more
+information about how orbiter works.

contrib/swarm/cluster/create.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+provider=virtualbox
+echo "### Init Servers ###"
+
+docker-machine create -d ${provider} sw1 &
+docker-machine create -d ${provider} sw2 &
+docker-machine create -d ${provider} sw3 &
+docker-machine create -d ${provider} sw4 &
+
+wait
+
+echo "### Configurate cluster ###"
+
+MANAGER_IP=$(docker-machine ip sw1)
+docker-machine ssh sw1 docker swarm init --advertise-addr ${MANAGER_IP}
+TOKEN=$(docker-machine ssh sw1 docker swarm join-token -q worker)
+docker-machine ssh sw2 docker swarm join --token ${TOKEN} ${MANAGER_IP}:2377
+docker-machine ssh sw3 docker swarm join --token ${TOKEN} ${MANAGER_IP}:2377
+docker-machine ssh sw4 docker swarm join --token ${TOKEN} ${MANAGER_IP}:2377
+
+# Information
+echo ""
+echo "CLUSTER INFORMATION"
+echo "discovery token: ${TOKEN}"
+echo "Environment variables to connect trough docker cli"
+docker-machine env sw1

contrib/swarm/stack.yml

@@ -0,0 +1,50 @@
+version: '3'
+services:
+  orbiter:
+    image: gianarb/orbiter
+    command: daemon
+    ports:
+      - 8081:8000
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+    deploy:
+      placement:
+        constraints:
+          - node.role == manager
+      mode: replicated
+      replicas: 1
+      resources:
+        limits:
+          cpus: '0.25'
+          memory: 512M
+        reservations:
+          cpus: '0.25'
+          memory: 256M
+  micro:
+    image: gianarb/micro:1.2.0
+    labels: [orbiter=true]
+    networks:
+      - micro-net
+    ports:
+      - 8000:8000
+    deploy:
+      mode: replicated
+      replicas: 10
+      labels: [orbiter=true]
+      update_config:
+        parallelism: 2
+        delay: 3s
+      resources:
+        limits:
+          cpus: '0.25'
+          memory: 512M
+        reservations:
+          cpus: '0.25'
+          memory: 256M
+        restart_policy:
+          condition: on-failure
+          delay: 3s
+          max_attempts: 3
+          window: 5s
+networks:
+  micro-net: