maint: NixOS module writes config to the Nix store

Instead of writing the config attrset to a YAML file to a fixed path in /etc,
this makes the NixOS module write to a (content-addressed) config file in the
Nix store. We just use builtins.toJSON since YAML is a superset of JSON.

default.nix

@@ -1,11 +1,12 @@
 let
-    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  lock = builtins.fromJSON (builtins.readFile ./flake.lock);
 in
-(import (
+  (import (
-  fetchTarball {
+      fetchTarball {
-    url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+        url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
-    sha256 = lock.nodes.flake-compat.locked.narHash;
+        sha256 = lock.nodes.flake-compat.locked.narHash;
-  }
+      }
-) {
+    ) {
-  src = ./.;
+      src = ./.;
-}).defaultNix
+    })
+  .defaultNix

examples/example_dashboards.yaml

@@ -8,10 +8,8 @@
         - source: http://heimdall:9001 # Prometheus source uri for this plot
           query: 'sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))' # The PromQL query for this plot
           meta: # metadata for this plot
-            name_label: instance # Grab a trace name from the query tags 
+            name_format: "`${labels.instance}`" # javascript template literal to format the trace name
             #d3_tick_format: "~%" # d3 tick format override for this plot's yaxis
-            #name_prefix: "Prefix" # A prefix for this sublots trace names
-            #name_suffix: "Suffix" # A suffix for this subplots trace names
             #named_axis: "y" # yaxis name to use for this subplots traces
       span: # The span for this range query
         end: now # Where the span ends. RFC3339 format with special handling for the now keyword
@@ -32,16 +30,14 @@
             sum by (instance)(irate(node_cpu_seconds_total{mode="system",job="nodestats"}[5m])) / sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))
           meta:
             d3_tick_format: "~%"
-            name_label: instance
+            name_format: "`${labels.instance} system`"
-            name_prefix: "System"
             named_axis: "y"
         - source: http://heimdall:9001
           query: |
             sum by (instance)(irate(node_cpu_seconds_total{mode="user",job="nodestats"}[5m])) / sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))
           meta:
             d3_tick_format: "~%"
-            name_label: instance
+            name_format: "`${labels.instance} user`"
-            name_suffix: "User"
             named_axis: "y"
     - title: Node memory
       query_type: Scalar
@@ -49,4 +45,4 @@
         - source: http://heimdall:9001
           query: 'node_memory_MemFree_bytes{job="nodestats"}'
           meta:
-            name_label: instance
+            name_format: "`${labels.instance}`"

flake.nix

@@ -6,149 +6,126 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
     naersk.url = "github:nix-community/naersk";
-    flake-compat = { url = github:edolstra/flake-compat; flake = false; };
+    flake-compat = {
+      url = github:edolstra/flake-compat;
+      flake = false;
+    };
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = {nixpkgs, flake-utils, naersk, rust-overlay, ...}:
+  outputs = {
+    nixpkgs,
+    flake-utils,
+    naersk,
+    rust-overlay,
+    ...
+  }:
     flake-utils.lib.eachDefaultSystem (system: let
       overlays = [
         rust-overlay.overlays.default
       ];
-      pkgs = import nixpkgs { inherit system overlays; };
+      pkgs = import nixpkgs {inherit system overlays;};
       rust-bin = pkgs.rust-bin.stable."1.71.0".default;
       naersk-lib = pkgs.callPackage naersk {
-          rustc = rust-bin;
+        rustc = rust-bin;
-          cargo = rust-bin;
+        cargo = rust-bin;
       };
       heracles = naersk-lib.buildPackage {
-          name = "heracles";
+        name = "heracles";
-          verion = "0.0.1";
+        verion = "0.0.1";
-          src = ./.;
+        src = ./.;
-          nativeBuildInputs = [ pkgs.pkg-config ];
+        nativeBuildInputs = [pkgs.pkg-config];
-          buildInputs = (
+        buildInputs =
-            if pkgs.stdenv.isDarwin then
+          (
-              with pkgs.darwin.apple_sdk.frameworks; [ Security SystemConfiguration ]
+            if pkgs.stdenv.isDarwin
-            else
+            then with pkgs.darwin.apple_sdk.frameworks; [Security SystemConfiguration]
-            [ pkgs.openssl ]) ++ [rust-bin];
+            else [pkgs.openssl]
+          )
+          ++ [rust-bin];
       };
-    in
+    in {
-    {
       packages.default = heracles;
-    }) // {
+      formatter = pkgs.alejandra;
-        nixosModule = {config, pkgs, lib}: with lib; {
+    })
-            options = {
+    // {
-                services.heracles.enable = mkEnableOption "enable heracles service";
+      nixosModules.default = {
-                services.heracles.listen = mkOption {
+        config,
-                    description = "[host]:port address for heracles to listen on";
+        pkgs,
-                    default = "localhost:8080";
+        lib,
-                    defaultText = "localhost:8080";
+      }: {
-                };
+        options = {
+          services.heracles.enable = lib.mkEnableOption "enable heracles service";
+          services.heracles.listen = lib.mkOption {
+            description = "[host]:port address for heracles to listen on";
+            default = "localhost:8080";
+            defaultText = "localhost:8080";
+            type = lib.types.string;
+          };
 
-                services.heracles.settings = mkOption {
+          services.heracles.settings = lib.mkOption {
-                    description = "heracles dashboard Configuration";
+            description = "heracles dashboard Configuration";
-                    default = [
+            type = lib.types.listOf lib.types.attrs;
+            default = [];
+            defaultText = lib.literalExpression ''
+              [
+                {
+                  title = "A dashboard";
+                  graphs = [
+                    {
+                      title = "Graph title";
+                      query_type = "Range";
+                      # yaxis formatting default for this graph
+                      d3_tick_format = "~s";
+                      plots = [
                         {
-                            title = "A dashboard";
+                          source = "http://heimdall:9001";
-                            graphs = [
+                          query = \'\'
-                                {
+                            sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))
-                                    title = "Graph title";
+                          \'\';
-                                    query_type = "Range";
+                          meta = {
-                                    # yaxis formatting default for this graph
+                            name_function = "''${labels.instance}";
-                                    d3_tick_format = "~s";
+                            named_axis = "y";
-                                    plots = [
+                            # yaxis formatting for this subplot
-                                        {
+                            d3_tick_format = "~s";
-                                            source = "http://heimdall:9001";
+                          };
-                                            query = ''
-                                                sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))
-                                            '';
-                                            meta = {
-                                                name_label = "instance";
-                                                name_prefix = "trace name prefix";
-                                                name_suffix = "trace name suffix";
-                                                named_axis = "y";
-                                                # yaxis formatting for this subplot
-                                                d3_tick_format = "~s";
-                                            };
-                                        }
-                                    ];
-                                    # span for this graph.
-                                    span = {
-                                        end = "now";
-                                        duration = "1d";
-                                        step_duration = "10min";
-                                    };
-                                }
-                            ];
-                            # default span for dashboard
-                            span = {
-                                end = "now";
-                                duration = "1d";
-                                step_duration = "10min";
-                            };
                         }
-                    ];
+                      ];
-                    defaultText = ''
+                      # span for this graph.
-                    [
+                      span = {
-                        {
+                        end = "now";
-                            title = "A dashboard";
+                        duration = "1d";
-                            graphs = [
+                        step_duration = "10min";
-                                {
+                      };
-                                    title = "Graph title";
+                    }
-                                    query_type = "Range";
+                  ];
-                                    # yaxis formatting default for this graph
+                  # default span for dashboard
-                                    d3_tick_format = "~s";
+                  span = {
-                                    plots = [
+                    end = "now";
-                                        {
+                    duration = "1d";
-                                            source = "http://heimdall:9001";
+                    step_duration = "10min";
-                                            query = \'\'
+                  };
-                                                sum by (instance)(irate(node_cpu_seconds_total{job="nodestats"}[5m]))
+                }
-                                            \'\';
+              ]
-                                            meta = {
+            '';
-                                                name_label = "instance";
+          };
-                                                name_prefix = "trace name prefix";
-                                                name_suffix = "trace name suffix";
-                                                named_axis = "y";
-                                                # yaxis formatting for this subplot
-                                                d3_tick_format = "~s";
-                                            };
-                                        }
-                                    ];
-                                    # span for this graph.
-                                    span = {
-                                        end = "now";
-                                        duration = "1d";
-                                        step_duration = "10min";
-                                    };
-                                }
-                            ];
-                            # default span for dashboard
-                            span = {
-                                end = "now";
-                                duration = "1d";
-                                step_duration = "10min";
-                            };
-                        }
-                    ]
-                    '';
-                };
-            };
-
-            config = mkIf config.services.heracles.enable {
-                environment.etc."heracles.yaml" = {
-                    text = (generators.toYAML {} config.services.heracles.settings);
-                };
-                systemd.services.heracles = {
-                    wantedBy = [ "multi-user.target" "default.target" ];
-                    wants = [ "network.target" ];
-                    after = [ "network-online.target" ];
-                    serviceConfig = {
-                        Restart = "on-failure";
-                        RestartSec = "30s";
-                        ExecStart = "${pkgs.heracles}/bin/heracles --listen ${config.services.heracles.listen} --config=${config.environment.etc."heracles.yaml".target}";
-                    };
-                };
-            };
         };
+
+        config = let
+          cfg = config.services.heracles;
+          cfgFile = pkgs.writeText "heracles.yaml" (builtins.toJSON cfg.settings);
+        in
+          lib.mkIf cfg.enable {
+            systemd.services.heracles = {
+              wantedBy = ["multi-user.target" "default.target"];
+              wants = ["network.target"];
+              after = ["network-online.target"];
+              serviceConfig = {
+                Restart = "on-failure";
+                RestartSec = "30s";
+                ExecStart = "${pkgs.heracles}/bin/heracles --listen ${cfg.listen} --config=${cfgFile}";
+              };
+            };
+          };
+      };
     };
 }

src/query.rs

@@ -117,9 +117,7 @@ pub struct DataPoint {
 
 #[derive(Serialize, Deserialize, Debug, Clone)]
 pub struct PlotMeta {
-    name_prefix: Option<String>,
+    name_format: Option<String>,
-    name_suffix: Option<String>,
-    name_label: Option<String>,
     named_axis: Option<String>,
     d3_tick_format: Option<String>,
 }

static/lib.js

@@ -160,19 +160,17 @@ class TimeseriesGraph extends HTMLElement {
                         yaxis: yaxis,
                         yhoverformat: meta["d3_tick_format"],
                     };
-                    const namePrefix = meta["name_prefix"];
-                    const nameSuffix = meta["name_suffix"];
-                    const nameLabel = meta["name_label"];
                     var name = "";
-                    if (namePrefix) {
+                    const formatter = meta.name_format
-                        name = namePrefix + "-";
+                    if (formatter) {
-                    };
+                        name = eval(formatter);
-                    if (nameLabel && labels[nameLabel]) {
+                    } else {
-                        name = name + labels[nameLabel];
+                        var names = [];
-                    };
+                        for (const value of labels) {
-                    if (nameSuffix) {
+                            names.push(value);
-                        name = name + " - " + nameSuffix;
+                        }
-                    };
+                        name = names.join(" ");
+                    }
                     if (name) { trace.name = name; }
                     for (const point of series) {
                         trace.x.push(new Date(point.timestamp * 1000));
@@ -190,17 +188,22 @@ class TimeseriesGraph extends HTMLElement {
                         type: "bar",
                         x: [],
                         y: [],
-                        yaxis: yaxis,
                         yhoverformat: meta["d3_tick_format"],
                     };
-                    let nameLabel = meta["name_label"];
+                    const formatter = meta.name_format;
-                    if (nameLabel && labels[nameLabel]) {
+                    var name = "";
-                        trace.name = labels[nameLabel];
+                    if (formatter) {
-                    };
+                        name = eval(formatter);
-                    if (nameLabel && labels[nameLabel]) {
+                    } else {
-                        trace.x.push(labels[nameLabel]);
+                        var names = [];
-                    };
+                        for (const value of labels) {
+                            names.push(value);
+                        }
+                        name = names.join(" ");
+                    }
+                    if (name) { trace.name = name; }
                     trace.y.push(series.value);
+                    trace.x.push(trace.name);
                     traces.push(trace);
                 }
             }