bash

BASH

This sample will show how to create an application that is nothing more than a bash script. While there is still an HTTP server as part of the solution, you should be able to reuse the bash container image in other projects without needing to do more than just provide a custom bash script.

In this setup the follow will happen:

• during the startup of each instance of your applciation, if present, a file named /app/init will be invoked. You can also set an environment variable called INIT to the path of an additional program that you want executed. The environment variable program will be called after /app/init. This allows for you to execute code that you want only run once per instance - and not on each incoming HTTP request.
• upon receiving an HTTP request, a file named /app/app will be invoked. The following environment variables will be set:
  • METHOD - the HTTP method (GET, POST,...) values
  • URL - the URL from the HTTP request
  • HEADER_xxx - where xxx is an HTTP header name, and the environment variable's value is the HTTP headers value. All HTTP headers will appear as environment variables.
• if /app/app exits with a zero exit code then an HTTP 200 OK will be returned. Otherwise an HTTP 503 Internal Server Error will be returned.
• if you define an environment variable called DEBUG then the application will print useful debugging information in the logs

The /app/init program in this sample will log into the IBM Cloud using an API Key provided in a secret. The /app/app program will invoke the ibmcloud ce app list command and return the result to the client.

As noted in the main README, this sample has two pieces:

• a build script which will build the container image(s) used
• a run script which deploys resources that use those images

The main purpose of this example is the run script, but the build script is included for complete educational (and reuse) purposes.