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{yen}

Stored queries

A stored query names a question about the fleet. r is the eval result. The other formal args are its parameters: required, unless they have a default.

modules/queries.nix
# A stored query names a question. `r` is the eval result; the other args are its parameters.
{ yen, lib, ... }:
{
  yen.queries = {
    aspectsOn =
      { r, host }:
      lib.sort (a: b: a < b) (
        lib.filter (a: r.active.${a}."fleet:main/host:${host}" or false) (lib.attrNames r.active)
      );
    hostsWith =
      {
        r,
        aspect,
        kind ? "host",
      }:
      map (s: s.name) (lib.filter (s: s.kind == kind && r.active.${aspect}.${s.id}) r.scopes);
  };
}

r.queries lists them with their parameters:

result
{
  aspectsOn = {
    optional = [ ];
    required = [
      "host"
    ];
  };
  hostsWith = {
    optional = [
      "kind"
    ];
    required = [
      "aspect"
    ];
  };
}

r.ask name args answers:

result
[
  "git"
  "nginx"
]

A wrong call is an error record, never a throw: a missing parameter, an unknown one, or an unknown query with near.

result
{
  class = "fixable";
  code = "missing-param";
  error = "query aspectsOn: missing host";
  from = "ask";
  got = [ ];
  path = [ ];
  want = [
    "host"
  ];
}
Terminal window
nix eval --impure --json --expr '(import ./query.nix).ask "aspectsOn" { host = "web"; }'
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