NGINX Unit Multi-App Demo

Requirements

• Docker Desktop or Docker Engine

Build

docker build --tag=unit-webapp .

Run

export UNIT=$(docker run -d --mount type=bind,src="$(pwd)/config",dst=/config \
                       --mount type=bind,src="$(pwd)/log",dst=/var/log \
                       --mount type=bind,src="$(pwd)/state",dst=/var/lib/unit \
                       --mount type=bind,src="$(pwd)/pythonapp",dst=/pythonapp \
                       --mount type=bind,src="$(pwd)/nodeapp",dst=/nodeapp \
                                   -p 8242:8242 -p 8243:8243 unit-webapp)

Applying Configurations

Included are 3 different config files to use in your demo. For instance, you can use the command below to configure NGINX Unit with the config/config.json file.

docker exec -ti $UNIT curl -X PUT --data-binary @/config/config.json http://localhost:9090/config

Demo Flow

• Once the container is up, apply the initial configuration in config/config.json using the following command:

docker exec -ti $UNIT curl -X PUT --data-binary @/config/config.json http://localhost:9090/config

• Navigate to the python flask app at http://localhost:8242 to show that it exists and is taking requests.
• Introduce the node express app by applying the configuration in config/config-2.json using the following command:

docker exec -ti $UNIT curl -X PUT --data-binary @/config/config-2.json http://localhost:9090/config

• Navigate to the node express app at http://localhost:8243/admin/
• Show that the python flask app is still running at http://localhost:8242
• Apply a new configuration in config/config-3.json which demonstrates the 2 applications running on a single port (leveraging routes) with the following command:

docker exec -ti $UNIT curl -X PUT --data-binary @/config/config-3.json http://localhost:9090/config

• Show the python flask app at http://localhost:8242 as well as the node express app at http://localhost:8242/admin/
• Navigate to the running unit config fetched by node express at http://localhost:8242/admin/config
• The application of config/config-3.json introduces the concept of scaling processes per application. Use the instructions in the Supplemental section below to highlight that there are now 4 node processes running as a result of applying this configuration.

Note: If you need to make a configuration change of your own creation, update json config file of your choosing then run the docker exec command in the "config" section above.

Supplemental

Open a bash shell into container if needed

docker exec -ti $UNIT bash

In the Docker container, use the ps command to see running processes running on the system with additional information. For example, if using config/config-3.json, there should be 4 node processes, and only 1 python process active.

ps aufx

Note: In the above command the -a option tells ps to list the processes of all users on the system rather than just those of the current user, -u and -f options tells ps to provide detailed and full information about each process. The -x option adds to the list processes that have no controlling terminal, such as daemon.

Removing and cleaning up existing containers and images on your system

USE WITH CAUTION!

docker ps -a -q --filter=ancestor=unit-webapp | xargs -I {} docker rm -f {}
docker rmi -f unit-webapp