This repo provides the basics for a Habitat demo consisting of 3 services: HAProxy, Tomcat, and MongoDB. Tomcat runs a National Parks application that displats the National Parks throughout the USA on a map.
Getting Started
To start the demo, clone this repo, cd into the resulting directory, and run the following.
habdemo $ docker-compose up
This will launch 3 containers, one for each service. By default, the MongoDB service launches as misconfigured (you'll see the national-parks service failing the init hook & constantly restarting because it can't connect to MongoDB). To launch a functional appstack, use the docker-compose-done.yml file instead of the default docker-compose.yml.
habdemo $ docker-compose -f docker-compose-done.yml up
Alternatively, you can fix the misconfigured MongoDB service, launch the habitat/utility container image - a container image to interact with the Habitat supervisors - in a second terminal.
habdemo $ ./run_util.sh
This launches the utility container on the appropriate network and drops you into a bash shell on that container. To reconfigure MongoDB, run the apply_mongo_config.sh script, passing the IP of the MongoDB container, this will apply a new config template (configs/mongo.toml) into the running habitat supervisor (using hap config apply), this config template sets the cluster_auth_mode="", which allows the app to connect to MongoDB.
[root@cf651c234c50 /]# cd /habdemo
[root@cf651c234c50 habdemo]# ./apply_mongo_config.sh 172.18.0.3
In your first terminal you should see the MongoDB service reconfigure itself, then the National Parks service successfully start. You should be able to interact with the application via the URL http://127.0.0.1:8080/national-parks.
You can also reconfigure HAProxy to enable the status page which is useful to show scaling of the application service, again this uses the hap config apply to apply a config template to a running supervisor.
[root@cf651c234c50 habdemo]# ./apply_haproxy_config.sh 172.18.0.4
The HAProxy status page can be accessed via the URL http://127.0.0.1:9000/haproxy-stats (u:admin p:password).
You can scale the application tier by using docker-compose.
habdemo $ docker-compose scale national-parks=10
This will launch nine additional containers and join them to the application's service group. Refresh the HAProxy status page to see that HAProxy automatically added the new containers to it's service. You can validate that all application servers are taking traffic by running ab (Apache Benchmark).
habdemo $ ab -n5000 http://127.0.0.1:8080/national-parks
Refreshing the HAProxy status page will show the Sessions count rising while ab executes, thus validating HAProxy properly reconfigured itself.
The Supervisor API for HAProxy can be accessed via the URL http://127.0.0.1:9631. Below are some URLs to show information the API exposes.