Comment by shawnz
13 days ago
It's still possible to break the config with a syntax error, but there are less kinds of syntax errors that are possible if you aren't writing into the middle of an existing block of syntax. For example, there's no chance that you unintentionally close an existing open block due to incorrect nesting of options or anything like that. Plus, if you are writing into the middle of an existing file, there's a chance you could corrupt other parts of the file besides the part you intended to write. For example, if you have an auto-generated section that you intend to update occasionally, you will need to make sure you only delete and recreate the auto-generated parts and don't touch any hand-written parts, which could involve complicated logic with sentinel comments, etc. Then you need to make sure that users who edit the file in future don't break your logic. In addition it's harder to test your automation code when you're writing into an existing file because there's more edge cases to deal with regarding the surrounding context, etc.
Templating doesn't write in the middle. Writing in the middle is a medieval rudiment of manual configuration helpers. Automated config generation simply outputs a new file every time you run "build" and then somehow syncs it to the target server. All "user" changes go into templates, not outputs. What you're talking about can exist, but it is a mutable hell that is not reproducible and thus cannot be a part of a reliable infrastructure.
If this is not how modern devops/fleet management works, I withdraw my questions cause it's even less useful than my scripts.