|
> Because let’s say it, everybody loves YAML. YAML is everywhere. Nope. Nope, nope, nope. I know a lot of people, including myself, who hates YAML with a passion. First, they hate the format itself. It's very easy to introduce hard-to-find typos. Plus it has multiple versions, no way to tell which one you use, and depending of the parser that ends up eating the file, you may get weird results. It's way worse then just the "Norway problem". Typically, a bad monday morning could look like this: >>> import yaml
>>> yaml.safe_load('''
port_mappings: 3333:33
alternative_port_mapping: 3333:33,
countries: [FR, US, UK, NO, IT]
1 : 1,0
2: 01
3: 1.0
4: 1O
5: 0b1
6: 0x1
7: 0i1
8: hey,
8.0: oh,
version: [3.1, "3.1", 3.10, "3.10"]
''')
Which may turn into this: {
'port_mappings': 200013,
'alternative_port_mapping': '3333:33,',
'countries': ['FR', 'US', 'UK', False, 'IT'],
1: '1,0',
2: 1,
3: 1.0,
4: '1O',
5: 1,
6: 1,
7: '0i1',
8: 'oh,',
'version': [3.1, '3.1', 3.1, '3.10']
}
It's a terrible, terrible format, that has too much variability, and way too many foot guns. Especially since typo-writing humans are supposed to edit those with their little clumsy hands.But worse, YAML is mostly declarative, so no complex system can be described in it. Here we come to the second reason people may hate it: it's usually turned into an even worse DSL. A very limited, badly designed, half documented and tested DSL with almost no tooling to write or debug the stuff. And each project has a different DSL, of course. Take Ansible. If your playbook is more than 10 lines, it becomes a pain to write because you are basically using a programming language embedded into a markup language. You have no print() or breakpoint to dive into the mess it does. It has to reinvent ways to pass values around since there are no functions with references to parameters nor return values. Mind you, this DSL calls Python under the hood, so they could have just exposed a declarative, idempotent Python API, but no. The entire world was required to recreate syntax highlighting, snippets, go-to-definition and so on for it. Which will never be good compared to the infra for real languages. There are few reasons to decide to use YAML, apart from "this is the only rich format supported out of the box by this system that has comments". Which I totally get, but still. If one can, use JSON, TOML or XML depending of the case, if we need only values. And if we need more than values, let's either define a clean, restricted API with a full blown programming language, or, if the use case requires it, use CUELang (https://cuelang.org/). CUELang is cleaner than YAML on all points, even for just data. It can provide a schema, can validate the data with that schema. It can embed logic. It can import and export from YAML and JSON so you stay compatible with the entire devops world. And it's not Turing complete, but has useful constructs to repeat, branch and reuse code. |
Maybe it's just me, but I read this as a joke. As much as we dislike YAML it's not really something we have the luxury of ignoring, especially in the infrastructure field.