feat(ci/cd): Set up Hydra

.hydra/jobsets.nix

@@ -0,0 +1,59 @@
+{
+  nixpkgs,
+  pulls,
+  ...
+}: let
+  pkgs = import nixpkgs {};
+
+  prs = builtins.fromJSON (builtins.readFile pulls);
+  prJobsets =
+    pkgs.lib.mapAttrs (
+      num: info: {
+        enabled = 1;
+        hidden = false;
+        description = "PR ${num}: ${info.title}";
+        checkinterval = 60;
+        schedulingshares = 20;
+        enableemail = false;
+        emailoverride = "";
+        keepnr = 1;
+        type = 1;
+        flake = "git+https://gitea.stefka.eu/jiriks74/zsh.nix/pull/${num}/head";
+      }
+    )
+    prs;
+  mkFlakeJobset = branch: {
+    description = "Build ${branch}";
+    checkinterval = "3600";
+    enabled = "1";
+    schedulingshares = 100;
+    enableemail = false;
+    emailoverride = "";
+    keepnr = 3;
+    hidden = false;
+    type = 1;
+    flake = "git+https://gitea.stefka.eu/jiriks74/zsh.nix/${branch}";
+  };
+
+  desc =
+    prJobsets
+    // {
+      "main" = mkFlakeJobset "main";
+    };
+
+  log = {
+    pulls = prs;
+    jobsets = desc;
+  };
+in {
+  jobsets = pkgs.runCommand "spec-jobsets.json" {} ''
+    cat >$out <<EOF
+    ${builtins.toJSON desc}
+    EOF
+    # This is to get nice .jobsets build logs on Hydra
+    cat >tmp <<EOF
+    ${builtins.toJSON log}
+    EOF
+    ${pkgs.jq}/bin/jq . tmp
+  '';
+}

.hydra/spec.json

@@ -0,0 +1,50 @@
+{
+  "enabled": 1,
+  "hidden": false,
+  "description": "ZSH flake",
+  "nixexprinput": "nixexpr",
+  "nixexprpath": ".hydra/jobsets.nix",
+  "checkinterval": 3600,
+  "schedulingshares": 100,
+  "enableemail": false,
+  "emailoverride": "",
+  "keepnr": 3,
+  "type": 0,
+  "inputs": {
+    "nixexpr": {
+      "value": "https://forgejo.stefka.eu/jiriks74/zsh.nix main",
+      "type": "git",
+      "emailresponsible": false
+    },
+    "nixpkgs": {
+      "value": "https://github.com/NixOS/nixpkgs nixos-unstable",
+      "type": "git",
+      "emailresponsible": false
+    },
+    "gitea_repo_name": {
+      "type": "string",
+      "value": "zsh.nix",
+      "emailresponsible": false
+    },
+    "gitea_repo_owner": {
+      "type": "string",
+      "value": "jiriks74",
+      "emailresponsible": false
+    },
+    "gitea_status_repo": {
+      "type": "string",
+      "value": "main",
+      "emailresponsible": false
+    },
+    "gitea_http_url": {
+      "type": "string",
+      "value": "https://forgejo.stefka.eu/",
+      "emailresponsible": false
+    },
+    "pulls": {
+      "type": "githubpulls",
+      "value": "jirik74 zsh.nix",
+      "emailresponsible": false
+    }
+  }
+}