@GrahamcOfBorg test traefik

LGTM!

[matt@servnerr-3:~/src/nixpkgs]$ cat /nix/store/ifi9fh33m7ysxzdx0qfzhldi7ix3sdjb-config.toml
[entryPoints]
  [entryPoints.web]
    address = ":80"

[global]
  checkNewVersion = false
  sendAnonymousUsage = false

[providers]
  [providers.docker]
    exposedByDefault = false
  [providers.file]
    filename = "/nix/store/c9v743dlz0x900y1rxf7g6ws3qbggdy2-config.toml"

This file should be the same, I haven't touched its generation. You are probably interested in the file provider - /nix/store/c9v743dlz0x900y1rxf7g6ws3qbggdy2-config.toml in your case

This patch seems to break my existing traefik configuration.

The underlying problem is that json doesn't distinguish between integers and floats, but both toml and nix do. So if I specify an integer value in dynamicConfigOptions, this is first converted to a json number by builtins.toJSON. Then, yj converts this json number to a toml float. So the type information is lost when converting to json.

While surprising, this is probably correct behavior on yj's part (see sclevine/yj#3). Still, this seems to make it impossible to specify traefik settings that expect integers via dynamicConfigOptions, as these integer settings are always converted to floats, which will then cause traefik to fail to load the resultant toml with Cannot start the provider *file.Provider: toml: cannot load TOML value of type float64 into a Go integer.

For example, lets take a look at the following traefik configuration:

services.traefik = {
  enable = true;
  staticConfigOptions.entryPoints."http"  = { address = ":80";  };
  dynamicConfigOptions = {
    http = {
      middlewares."ratelimit".ratelimit = {
        average = 1;
        burst = 10;
      };
      routers."subdomains" = {
        rule = "HostRegexp(`{subdomain:[a-z]+}.example.com`)";
        service = "nginx";
        middlewares = [ "ratelimit" ];
        priority = 1;
      };
      services."nginx".loadBalancer.servers = [{ url = "h2c://[::1]:8001"; }];
    };
  };
};

the above is converted to the following (dynamic) configuration file:

[http]
  [http.middlewares]
    [http.middlewares.ratelimit]
      [http.middlewares.ratelimit.ratelimit]
        average = 1.0
        burst = 10.0
  [http.routers]
    [http.routers.subdomains]
      middlewares = ["ratelimit"]
      priority = 1.0
      rule = "HostRegexp(`{subdomain:[a-z]+}.example.com`)"
      service = "nginx"
  [http.services]
    [http.services.nginx]
      [http.services.nginx.loadBalancer]

        [[http.services.nginx.loadBalancer.servers]]
          url = "h2c://[::1]:8001"

As you can see, the average, burst and priority settings have their types converted, causing traefik to fail to load this dynamic configuration.

This broke my config also, and was a nightmare to hunt down. @alyssais please revert

Reverted in 5b8b201

This is addressed in yj v5.0.0 (even though the previous behavior technically adheres to the spec).

 onyx:yj stephen$ echo '{"a": 1}'|./yj -jt
a = 1
 onyx:yj stephen$ echo '{"a": 1.0}'|./yj -jt
a = 1.0