Pulp

Most services that run on kubernetes try to not require a config file at all, or at least make it optional. They'll accept settings both as command-line arguments and as environment variables, with the command-line args usually winning in case both are used. Here are a couple of options that would be reasonable and fit convention.

1. Somewhere pulp is parsing a config file and storing the values it finds in a structure that gets used in code. That point of parsing is a reasonable place to also look for an environment variable and let it override any setting found in the file. Here is a popular go library that takes such an approach, which may be interesting as an example: https://github.com/spf13/viper

2. Run a small entrypoint script in your container that reads environment variables and uses them to create the yaml file on the spot, then exec pulp's process. Such scripts are very common for doing environmental setup of that variety.

3. Store the whole config file in a kubernetes Secret, mount it into the pod as a file, and symlink from the path where Pulp expects it to be found to wherever you mounted it. One advantage here is that you can make just one secret and mount it into all the pods. That's the approach I took here: https://github.com/mhrivnak/pulp-k8s

Hopefully that's helpful. Feel free to ping me if you'd like to chat more about any of it.

For my near-term needs I used a bash script to read environment variables and write the necessary yaml config. For the future I think switching to a Python settings file would resolve several issues including this one.