sconf config format is a bit cumbersome: rigid tab requirement, extremely long lines, etc. #319

QuadrupleA · 2025-03-23T17:06:38Z

I love mox's self-documentation design (the config is the docs, and compiled into the executable) and its well-thought-out config organization.

This is just personal opinion and feel free to ignore, but I feel like the sconf format is a roadblock here, and hindering ease of use quite a bit.

Firstly: the requirement to use tabs - the default VIM config on most systems (and many other editors) uses 8-space tabs, which makes indents quite large and unwieldly. Python, the most common and popular "whitespace is significant" language like this, recommends spaces. YAML doesn't even allow tabs. Many modern text editors automatically replace tabs with spaces by default.

So automatically users are fighting against the tide trying to edit mox.conf and domains.conf without breaking them.

Secondly: long lines - my mox.conf has lines that blow out to 126 characters (e.g. CertFile paths), so while every other service I administer can happily work in a small 80x25 terminal window alongside other windows, mox always forces me to maximize the window or stretch it to take up half my screen. Granted we have big screens now, this isn't 1985, but there's kind of a defacto standard of 80-90 columns ish which makes it nice when dealing with a lot of different services. Incidentally this is also good typography and good for readability.

JSON5 could be an awesome drop-in replacement for sconf (it has a few popular go implementations). Basically JSON but relaxed somewhat, allowing comments, trailing commas, etc.

Whitespace no longer an issue, spaces/tabs are fine (2-space indents would be good here)
JSON is super common and well-understood, likely no learning curve for users
Semantically identical to sconf - I suspect it could be parsed into the exact same internal representation
No awkward '-' on empty lines
Small lists (like IPs below) can be one-liners

Sample:

{
  // Directory where all data is stored, e.g. queue, accounts and messages,
  // ACME TLS certs/keys. If this is a relative path, it is relative to the
  // directory of mox.conf.
  DataDir: "../data",

  // Full hostname of system, e.g. mail.<domain>
  Hostname: "mail.example.com",

  // Listeners are groups of IP addresses and services enabled on those IP
  // addresses, such as SMTP/IMAP or internal endpoints for administration 
  // or Prometheus metrics. All listeners with SMTP/IMAP services enabled 
  // will serve all configured domains. If the listener is named 'public', 
  // it will get a few helpful additional configuration checks, for acme
  // automatic tls certificates and monitoring of ips in dnsbls if those 
  // are configured.
  Listeners: {
    internal: {

      // ...
      IPs: ["1.2.3.4", "127.0.0.1"],
    }
  }

  // ...
}

Again just my opinion - don't know all the internal considerations so feel free to ignore. But loving this project overall and I feel like it serves an important mission, to help decentralize email and make it more accessible to self-hosters, so would hate the config format to get in the way.

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mjl- · 2025-03-27T12:50:06Z

Hi @QuadrupleA, thanks for creating the issue, certainly appreciated.

I think you're right that the sconf format is causing confusion to some/plenty of people. It's essentially a new format. Indeed spaces are more common, YAML is used a lot. I understand how spaces have come about, with copy/paste in terminals often converting selected tabs into spaces. In my mind, that's the fault of the terminals or terminal editors, but that line of reasoning isn't helping anyone. Personally, in terminals I edit with vim, and typing tabs is easier than typing spaces, in part because on the machines where I use it, "AI" (autoindent) is disabled by default. When copying text, I sometimes filter it through unexpand to get my tabs back. Are terminal editors really commonly inserting spaces for indenting by default? I would hope modern editors automatically detect whether tabs or spaces are used in files, and work with that.

The long lines also don't bother me. They just wrap to the next line. Only when editors wouldn't wrap long lines, but hide part of the line, that would sound annoying. But that's not the default in the terminal editors I use. Perhaps for some? Would be interesting to understand how this works for others.

I'm not a big fan of JSON for config files. It requires typing too much syntax in my opnion. JSON5 is indeed better, but still requires typing typed values.

Anyway, I can understand why sconf can be troublesome for some. We could look at something better. There's a lot of other work to do on mox, so it's not high on my priority list. It's also somewhat tricky to change the file format with existing installs out there.

It would be useful to hear from people who do or don't have problems with sconf. What are the common problems? Typing and/or typing tabs vs spaces? Or learning the syntax (lists)? Or the line lengths?

QuadrupleA · 2025-03-27T17:44:48Z

Sure thing, thanks for the reply.

Yeah, unfortunately tabs are visually inconsistent thanks to legacy tooling / inconsistencies. Maybe sconf could support both ala python, where it just takes the first indent it discovers as the official "indent unit"? You're probably right that space-ifying tabs (e.g. VIM's "expandtab") isn't default in most editors, although I do use it in my own dev / .vimrc's.

Here's what I get with the default .vimrc (haven't customized it on root on my mail VM) with ts=8 etc. on an 80x25 viewing mox.conf:

                # set new password, set new delivery rulesets. Default path
is /. (optional)
                AccountHTTP:
                        Enabled: true

                        # Default 80 for HTTP and 443 for HTTPS. See Hostname at
Listener for hostname
                        # matching behaviour. (optional)
                        Port: 1080

                        # If set, X-Forwarded-* headers are used for the remote
IP address for rate
                        # limiting and for the "secure" status of cookies. 
(optional)
                        Forwarded: false

                # Admin web interface, for managing domains, accounts, etc.
Default path is
                # /admin/. Preferably only enable on non-public IPs. Hint: use
'ssh -L
                # 8080:localhost:80 you@yourmachine' and open http://localhost:
8080/admin/, or set

VS code etc. wraps more nicely, keeping it under the line's indent.

Personally I don't mind the extra { or " here or there in JSON, and I like the explicitness of it. Probably the least learning curve too due to its ubiquity.

Your call in the end of course, you obviously have a good design sense of keeping things simple which shines through in mox. And more important priorities for sure. As it gets more popular you'll probably have to battle a lot of people trying to convince you to add their pet features and complicate things, hope I'm on the simplicity side and not the pet-feature side :)

Curious to hear others' thoughts too.

kjetilho · 2025-04-02T20:16:17Z

I agree with QuadrupleA here. It really looks messy in a normal terminal. TAB is exactly 8 characters, so we get very deep indents which makes it hard to see the flow. The overlong lines as seen above do not help.

It's often been said that the biggest mistake the make author made was to make TAB a part of the syntax. This is repeating that ancient mistake.

I also am not too fond of only supporting verbatim single-line string values. Trailing whitespace is significant, and it is impossible to write a comment on the same line as the value. Explicit is better than implicit, which is why I prefer relaxed JSON over the mess that is YAML (too many edge cases cause problems for interoperability, e.g., the well known Norway problem.)

That said, there is one really good thing about sconf: automatic schema validation since this maps exactly Golang structs. Every typo or missing required value will be caught automatically without the need to add explicit validation code.

There is an interesting project kalled Pkl which adds a schema layer to existing configuration files. It does not support generation of Sconf (yet?!) - but it does have native support for Go - so perhaps that is worth a look?

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sconf config format is a bit cumbersome: rigid tab requirement, extremely long lines, etc. #319

sconf config format is a bit cumbersome: rigid tab requirement, extremely long lines, etc. #319

sconf config format is a bit cumbersome: rigid tab requirement, extremely long lines, etc. #319

sconf config format is a bit cumbersome: rigid tab requirement, extremely long lines, etc. #319

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