This sample project contains many different components, namely:

• Docker: for containerizing services
• Flask: Python framework to quickly create REST services
• uWSGI: Python framework to support WSGI (Web Server Gateway Interface)
• Consul: Automated service discovery
• Registrator: Automatically listen to expose port of each running docker container, and register it as a consul-service
• NGINX: A HTTP and Reverse Proxy server
• Consul-Template: A templating tool that checks consul server periodically and use the information to generate configurations (e.g. nginx configurations)

Testing running consul in docker in OS X.

Just me trying to understand how consul works within docker within OSX. To get started, run

# Create docker machine and set the environment of it
docker-machine create default
eval $(docker-machine env)

# Because we use DOCKER_MACHINE_IP environment variable in the docker-compose.yml
export DOCKER_MACHINE_IP=$(docker-machine ip)

# Start docker compose, forcing it to build if necessary, and run it detached
docker-compose up --build -d

Then you could check for consul membership and registered services:

# Check for the consul nodes
consul members --http-addr=$(docker-machine ip):8500

# Check for the registered services, json_pp is for pretty printing JSON, use jq if you're in linux
curl $(docker-machine ip):8500/v1/catalog/services | json_pp

# Check for the specific service
curl $(docker-machine ip):8500/v1/catalog/service/hello-server | json_pp

Then finally you could do a proof of concept, using call-server to call hello-server internally using Consul's discovery service

# Run curl onto call-server service in consul, and use jq to obtain the port number
curl -s $(docker-machine ip):8500/v1/catalog/service/call-server | jq -r '.[].ServicePort'

# for example it returns me
# 32777
# Now we could call call-server at port 32777

curl -s $(docker-machine ip):32777

# And it should print out something similar to below
{"CreateIndex": 384, "ServicePort": 32776, "ServiceTags": [], "ModifyIndex": 384, "ServiceEnableTagOverride": false, "Node": "bootstrap-node", "ID": "102b597f-0b4c-4702-985e-327a5a022cc7", "NodeMeta": {}, "TaggedAddresses": {"wan": "192.168.99.100", "lan": "192.168.99.100"}, "Address": "192.168.99.100", "ServiceName": "hello-server", "ServiceID": "ab1720162e4c:hello-server:80", "ServiceAddress": "192.168.99.100"} Hello World

We're using Consul-Template + NGINX to do reverse proxy and automatic load balancing, thus now the hello-server and call-server services can be accessed from:

curl -s $(docker-machine ip)/api/hello-server
curl -s $(docker-machine ip)/api/call-server