docker: add base umami config

This is the start of using docker containers for the server services as
opposed to using NixOS modules.

In a future commit APP_SECRET will be changed to not expose the actual
secret.

home/docker.nix

@@ -0,0 +1,72 @@
+let
+  inherit (builtins) toJSON;
+in
+{
+  xdg.configFile."docker/compose.yml".text = toJSON {
+    services = {
+      umami = {
+        image = "ghcr.io/umami-software/umami:postgresql-latest";
+        container_name = "umami";
+        restart = "always";
+
+        ports = [
+          "3000:3000"
+        ];
+
+        environment = {
+          DATABASE_URL = "postgresql://umami:umami@umami-postgres:5432/umami";
+          DATABASE_TYPE = "postgresql";
+          APP_SECRET = "replace-me-with-a-random-string";
+        };
+
+        depends_on = {
+          umami-postgres = {
+            condition = "service_healthy";
+          };
+        };
+
+        healthcheck = {
+          test = [
+            "CMD-SHELL"
+            "curl http://localhost:3000/api/heartbeat"
+          ];
+
+          interval = "5s";
+          timeout = "5s";
+          retries = 5;
+        };
+      };
+
+      umami-postgres = {
+        image = "postgres:17-alpine";
+        container_name = "umami-postgres";
+        restart = "always";
+
+        environment = {
+          POSTGRES_DB = "umami";
+          POSTGRES_USER = "umami";
+          POSTGRES_PASSWORD = "umami";
+        };
+
+        volumes = [
+          "umami-postgres:/var/lib/postgresql/data"
+        ];
+
+        healthcheck = {
+          test = [
+            "CMD-SHELL"
+            "pg_isready -U $${POSTGRES_USER} -d $${POSTGRES_DB}"
+          ];
+
+          interval = "5s";
+          timeout = "5s";
+          retries = 5;
+        };
+      };
+    };
+
+    volumes = {
+      umami-postgres = { };
+    };
+  };
+}