feat: add tempo service (#192)

.gitignore

@@ -7,5 +7,6 @@
 # created when `just run ex-*` is used
 /example/share-services/pgweb/data/
 /example/simple/data/
+/example/grafana-tempo/data/
 
 /.pre-commit-config.yaml

doc/services.md

@@ -18,6 +18,7 @@ short-title: Services
   - [[redis-cluster]]
 - [[zookeeper]]#
 - [[grafana]]#
+  - [[tempo]]
 - [[prometheus]]#
 - [[cassandra]]#
 

doc/tempo.md

@@ -0,0 +1,36 @@
+# Grafana Tempo
+
+[Grafana Tempo](https://grafana.com/docs/tempo/latest/) is an open-source, easy-to-use, and high-scale distributed tracing backend. Tempo lets you search for traces, generate metrics from spans, and link your tracing data with logs and metrics.
+
+## Getting Started
+
+```nix
+# In `perSystem.process-compose.<name>`
+{
+  services.tempo."tp1".enable = true;
+}
+```
+
+{#tips}
+## Tips & Tricks
+
+{#usage-with-grafana}
+### Usage with Grafana
+
+To add tempo as a datasource to #[[grafana]], we can use the following config:
+
+```nix
+{
+  services.tempo.tp1.enable = true;
+  services.grafana.gf1 = {
+    enable = true;
+    datasources = with config.services.tempo.tp1; [{
+      name = "Tempo";
+      type = "tempo";
+      access = "proxy";
+      url = "http://${httpAddress}:${builtins.toString httpPort}";
+    }];
+  };
+  settings.processes."gf1".depends_on."tp1".condition = "process_healthy";
+}
+```

example/grafana-tempo/flake.nix

@@ -0,0 +1,42 @@
+{
+  description = "A demo of grafana with tempo";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    systems.url = "github:nix-systems/default";
+    process-compose-flake.url = "github:Platonic-Systems/process-compose-flake";
+    services-flake.url = "git+file:///Volumes/Code/services-flake";
+  };
+  outputs = inputs:
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = import inputs.systems;
+      imports = [
+        inputs.process-compose-flake.flakeModule
+      ];
+      perSystem = { self', pkgs, lib, ... }: {
+        # `process-compose.foo` will add a flake package output called "foo".
+        # Therefore, this will add a default package that you can build using
+        # `nix build` and run using `nix run`.
+        process-compose."default" = { config, ... }: {
+          imports = [
+            inputs.services-flake.processComposeModules.default
+          ];
+
+          services.tempo."tp1".enable = true;
+          services.grafana."gf1" = {
+            enable = true;
+            datasources = with config.services.tempo.tp1; [{
+              name = "Tempo";
+              type = "tempo";
+              access = "proxy";
+              url = "http://${httpAddress}:${builtins.toString httpPort}";
+            }];
+          };
+        };
+
+        devShells.default = pkgs.mkShell {
+          nativeBuildInputs = [ pkgs.just ];
+        };
+      };
+    };
+}

example/grafana-tempo/justfile

@@ -0,0 +1,2 @@
+default:
+    nix run

nix/default.nix

@@ -17,5 +17,6 @@ in
     ./prometheus.nix
     ./pgadmin.nix
     ./cassandra.nix
+    ./tempo.nix
   ];
 }

nix/grafana.nix

@@ -2,6 +2,7 @@
 let
   inherit (lib) types;
   iniFormat = pkgs.formats.ini { };
+  yamlFormat = pkgs.formats.yaml { };
 in
 {
   options = {
@@ -48,6 +49,32 @@ in
       '';
     };
 
+    datasources = lib.mkOption {
+      type = types.listOf yamlFormat.type;
+      description = "List of data sources to configure.";
+      default = [ ];
+      example = ''
+        [
+          {
+            name = "Tempo";
+            type = "tempo";
+            access = "proxy";
+          }
+        ]
+      '';
+    };
+
+    deleteDatasources = lib.mkOption {
+      type = types.listOf yamlFormat.type;
+      description = "List of data sources to remove.";
+      default = [ ];
+      example = ''
+        [
+          { name = "Tempo"; }
+        ]
+      '';
+    };
+
     outputs.settings = lib.mkOption {
       type = types.deferredModule;
       internal = true;
@@ -63,6 +90,23 @@ in
               }
               config.extraConf;
             grafanaConfigIni = iniFormat.generate "defaults.ini" grafanaConfig;
+            provisioningConfig = pkgs.stdenv.mkDerivation {
+              name = "grafana-provisioning";
+              datasourcesYaml = yamlFormat.generate "datasources.yaml" {
+                apiVersion = 1;
+                deleteDatasources = config.deleteDatasources;
+                datasources = config.datasources;
+              };
+              buildCommand = ''
+                mkdir -p $out
+                mkdir -p $out/alerting
+                mkdir -p $out/dashboards
+                mkdir -p $out/datasources
+                ln -s "$datasourcesYaml" "$out/datasources/datasources.yaml"
+                mkdir -p $out/notifiers
+                mkdir -p $out/plugins
+              '';
+            };
             startScript = pkgs.writeShellApplication {
               name = "start-grafana";
               runtimeInputs =
@@ -73,7 +117,8 @@ in
               text = ''
                 grafana server --config ${grafanaConfigIni} \
                                --homepath ${config.package}/share/grafana \
-                               cfg:paths.data="$(readlink -m ${config.dataDir})"
+                               cfg:paths.data="$(readlink -m ${config.dataDir})" \
+                               cfg:paths.provisioning="${provisioningConfig}"
               '';
             };
           in