README
¶
Cats and Dogs
A sample app to demonstrate communication (HTTP and UDP) between a frontend and a backend application over the container network.
This app also demonstrates how to use service discovery with container networking. To see this, you must also deploy with service discovery enabled.
We're assuming that you've deployed to BOSH lite.
If you've deployed to AWS or another environment,
substitute bosh-lite.com below with the domain name of your installation.
To configure policies you use the CF CLI.
Frontend
The frontend serves a form at http://frontend.bosh-lite.com/.
The frontend allows you to test out container network communication via two methods:
- connect to the backend via HTTP
- connect to the backend via UDP
In either case, the response from the backend to the frontend will be rendered as a web page.
Deploying
cd cf-networking-release/src/example-apps/cats-and-dogs/frontend
cf api api.bosh-lite.com --skip-ssl-validation
cf auth admin admin
cf push frontend
Backend
The backend displays its platform-generated internal hostname and container network IP if you visit http://backend.bosh-lite.com/.
Note: the platform-generated internal hostname will only work if cf was deployed with service discovery.
The backend serves pictures of cats on the TCP ports specified in the environment variable CATS_PORTS,
and responds to simple text messages on the UDP ports specified in the environment variable UDP_PORTS.
Deploying
cd cf-networking-release/src/example-apps/cats-and-dogs/backend
cf push backend --no-start
cf set-env backend CATS_PORTS "7007,7008"
cf set-env backend UDP_PORTS "9003,9004"
cf set-env backend APP_GUID $(cf app backend --guid)
cf start backend
Usage
After both frontend and backend apps have been deployed, you can visit http://backend.bosh-lite.com/
in a browser. You should see something like:
My overlay IP is: 10.255.76.2
My internal hostname is: <app-guid>.apps.internal
I'm serving cats on TCP ports 7007,7008
I'm also serving a UDP echo server on UDP ports 9003,9004
If you were to visit http://frontend.bosh-lite.com, you should see something like:
Frontend Sample App
HTTP Test
Backend HTTP URL: [....] [ Submit ]
UDP Test
Backend UDP Server Address: [....]
Message: [....] [ Submit ]
Usage with HTTP
In Backend HTTP URL enter the backend's internal hostname and a cats port (<app-guid>.apps.internal:7007).
Hit submit.
If service discovery is not enabled, you may use the backend's overlay IP in place of the hostname.
You will see an error message saying the connection is refused. This is because the two apps have not been configured to allow connections from the frontend to the backend.
If you see an error message saying no such host, service discovery is incorrectly configured.
Now allow access:
cf add-network-policy frontend --destination-app backend --port 7007 --protocol tcp
Now if you try again from the frontend:
[GIF OF CAT]
Hello from the backend, port: 7007
Usage with UDP
In Backend UDP Server Address enter the backend's internal hostname and UDP port
(<app-guid>.apps.internal:9003) and a message. Hit submit.
If service discovery is not enabled, you may use the backend's overlay IP in place of the hostname.
You will see an error message. This is because the two apps have not been configured to allow connections from the frontend to the backend.
Now allow access:
cf add-network-policy frontend --destination-app backend --port 9003 --protocol udp
Now if you try again from the frontend:
You sent the message: hello world
Backend UDP server replied: HELLO WORLD
Directories