Something I didn't appreciate before working in a very large tech company was just how much of a difference a good configuration language makes. In my previous company, configuration was a mix of YAML, JSON, and hardcoded values in Python. While this worked fine, deficiencies in YAML/JSON meant that we often had additional tooling around those files to generate more config.
At Google, languages like Starlark are used to build entire software stacks that run at configuration-time. Configuration with a base language, libraries, domain-specific languages, team-specific utilities, conventions, linters, and the whole thing gets built into a package that can be run by some much more general server.
That level of complexity is unnecessary in many places, but the one thing I would take on elsewhere is to pick a good, capable, config language early, and then use it for as much config as possible. Starlark is a good option if you like Python-ish stuff, Jsonnet is also pretty nice.
At Google, languages like Starlark are used to build entire software stacks that run at configuration-time. Configuration with a base language, libraries, domain-specific languages, team-specific utilities, conventions, linters, and the whole thing gets built into a package that can be run by some much more general server.
That level of complexity is unnecessary in many places, but the one thing I would take on elsewhere is to pick a good, capable, config language early, and then use it for as much config as possible. Starlark is a good option if you like Python-ish stuff, Jsonnet is also pretty nice.