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Why are we templating YAML?

leebriggs.co.uk

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Re: Why are we templating YAML?

#71

Post by atombender »

BossingAround wrote: post #27

I know I'm in a minority, but I really dislike YAML... I recently did a lot of Ansible and boy, at the beginning, I was just struggling a lot. Syntactic whitespace kills me. I don't like it in Python either, but for some reason, when I write Python, it's a lot easier. Maybe YAML is just a bit more complex (and Python has better IDE support..?)

YAML is a bit bonkers in that it's a superset of JSON (all valid JSON is valid YAML), so if you don't like the whitespace sensitivity, you can write your YAML like this:

  {
    a: 42,
    # But you can have comments!
    b: "hello world",
    c: "and
      multi-line
      strings!",  # and trailing commas!
  }

Re: Why are we templating YAML?

#72

Post by ilovetux »

BossingAround wrote: post #27

I know I'm in a minority, but I really dislike YAML... I recently did a lot of Ansible and boy, at the beginning, I was just struggling a lot. Syntactic whitespace kills me. I don't like it in Python either, but for some reason, when I write Python, it's a lot easier. Maybe YAML is just a bit more complex (and Python has better IDE support..?)

I find YAML to be almost unusable. IMO it's just not intuitive. If I get to choose a format for my config files I would only use TOML, it's just better (again IMO).

Re: Why are we templating YAML?

#73

Post by necubi »

svnpenn wrote: post #51
aetherlord wrote: post #23

I didn't see this mentioned anywhere else, so another alternative (that I've seen and really like conceptually, but haven't used so far) to all this wildness with YAML and JSON -> https://github.com/dhall-lang/dhall-lang , and for kubernetes specifically -> https://github.com/dhall-lang/dhall-kubernetes

god those examples are ugly - commas at the beginning of a line? mismatched brace styles?

It's a haskell thing. The main advantage is that each line is independent. You can comment out a line or add a line at the end without modifying anything else.

Re: Why are we templating YAML?

#75

Post by guitarbill »

deathanatos wrote: post #45
MrStonedOne wrote: post #2

The real question is why are we using yaml at all?

Easier to read and write than JSON. JSON requires constant quoting, can't support multiline strings, has no comments, has no/little typing (e.g., no datetime type). It's not good if a human needs to encode data. For configs, I think TOML beats YAML hands down; I think YAML's spot is at encoding data structures that humans need to read/write. I do agree that YAML, the spec, is fairly complicated. But YAML, as used in…

It's worth giving Ansible some credit here. Alternatives like Chef, can and do contain arbitrary Ruby logic which can make Chef "cookbooks" horrible to figure out and debug.

So while Ansible may not be great, other solutions also have drawbacks, and it isn't quite as easy as do .

Re: Why are we templating YAML?

#76

Post by desc »

My approach to this these days is:

* all configuration, without exception, is XML.

* all configuration may be generated from any other format imaginable, but it's sure as fuck going into the Big Main Godlike Application as XML.

Separation, interfaces, etc. Disclaimer: I work in .NET almost exclusively. The .NET configuration APIs generally work, as long as you only ever use them for reading; treating config as something the application itself can fiddle with is a fast route to madness.

Re: Why are we templating YAML?

#77

Post by chriswarbo »

svnpenn wrote: post #51
aetherlord wrote: post #23

I didn't see this mentioned anywhere else, so another alternative (that I've seen and really like conceptually, but haven't used so far) to all this wildness with YAML and JSON -> https://github.com/dhall-lang/dhall-lang , and for kubernetes specifically -> https://github.com/dhall-lang/dhall-kubernetes

god those examples are ugly - commas at the beginning of a line? mismatched brace styles?

Not sure what you mean by "mismatched brace styles". The convention of putting separators like commas at the start of the following line rather than the end of the preceding line is common in Haskell, which Dhall is built with.

The advantages are:

- All of the separators are in the same column, along with the opening and closing characters. This makes it trivial to check if we've missed a separator.

- Appending new lines to the end will not affect previous lines (i.e. we don't need to go and add a comma). This avoids making mistakes and polluting diffs.

Unfortunately the error-prone diff pollution we avoid at the last line instead occurs at the first line. It's still less error-prone than trailing commas, since we can look in the separator column and either spot that it's empty, or that it contains two opening braces (depending on whether we inserted or copy/pasted).

Re: Why are we templating YAML?

#78

Post by tomrod »

atombender wrote: post #71
BossingAround wrote: post #27

I know I'm in a minority, but I really dislike YAML... I recently did a lot of Ansible and boy, at the beginning, I was just struggling a lot. Syntactic whitespace kills me. I don't like it in Python either, but for some reason, when I write Python, it's a lot easier. Maybe YAML is just a bit more complex (and Python has better IDE support..?)

YAML is a bit bonkers in that it's a superset of JSON (all valid JSON is valid YAML), so if you don't like the whitespace sensitivity, you can write your YAML like this: { a: 42, # But you can have comments! b: "hello world", c: "and multi-line strings!", # and trailing commas! }

Oh hey, a Python dictionary that throws an error. Just kidding -- faced a JSON parsing issue today and this made me smile.

It's a step up from XML though.

Re: Why are we templating YAML?

#79

Post by jrockway »

I saw this title and immediately knew the article would be about Helm. I don't think anyone wants to use Helm. People use it for a set-and-forget thing that they don't care about (who cares that it's called impressive-leopard-kubernetes-dashboard, after all.)

kustomize is much more sane for your own stuff: https://github.com/kubernetes-sigs/kustomize

It is actually a little bit too magical for my taste, but I continue to use it because it hasn't done anything stupid. I have one file that maps logical names to images in a container repository. If I create a service called "foo" pointing to selector.app.label="foo" in the base, then in production it's called foo-prd and the label magically updates to foo-prd for the selector. It actually understands what it's generating, and while they might have taken it a little bit too far, it's far better than just dumb text replacement.

Re: Why are we templating YAML?

#80

Post by jrockway »

the8472 wrote: post #14

Helm reminds me of the 90s level of webtech. I.e. php cgi files mixing html, logic and includes.

I believe people are back to doing that for web stuff. Open up any modern web stuff and it looks like "const widget = foo".

Not making this up! https://reactjs.org/docs/introducing-jsx.html

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