nixos/prometheus: Added remote-write test case

nixos/tests/prometheus/default.nix

@@ -5,4 +5,5 @@
 
 {
   prometheus-pair = import ./prometheus-pair.nix { inherit system pkgs; };
+  remote-write = import ./remote-write.nix { inherit system pkgs; };
 }

nixos/tests/prometheus/remote-write.nix

@@ -0,0 +1,73 @@
+import ../make-test-python.nix ({ lib, pkgs, ... }:
+
+{
+  name = "prometheus-remote-write";
+
+  nodes = {
+    receiver = { config, pkgs, ... }: {
+      environment.systemPackages = [ pkgs.jq ];
+
+      networking.firewall.allowedTCPPorts = [ config.services.prometheus.port ];
+
+      services.prometheus = {
+        enable = true;
+        globalConfig.scrape_interval = "2s";
+
+        extraFlags = [ "--web.enable-remote-write-receiver" ];
+      };
+    };
+
+    prometheus = { config, pkgs, ... }: {
+      environment.systemPackages = [ pkgs.jq ];
+
+      networking.firewall.allowedTCPPorts = [ config.services.prometheus.port ];
+
+      services.prometheus = {
+        enable = true;
+        globalConfig.scrape_interval = "2s";
+
+        remoteWrite = [
+          {
+            url = "http://receiver:9090/api/v1/write";
+          }
+        ];
+
+        scrapeConfigs = [
+          {
+            job_name = "node";
+            static_configs = [
+              {
+                targets = [
+                  "node:${toString config.services.prometheus.exporters.node.port}"
+                ];
+              }
+            ];
+          }
+        ];
+      };
+    };
+
+    node = { config, pkgs, ... }: {
+      services.prometheus.exporters.node = {
+        enable = true;
+        openFirewall = true;
+      };
+    };
+  };
+
+  testScript = ''
+    node.wait_for_unit("prometheus-node-exporter")
+    node.wait_for_open_port(9100)
+
+    for machine in prometheus, receiver:
+      machine.wait_for_unit("prometheus")
+      machine.wait_for_open_port(9090)
+
+    # Verify both servers got the same data from the exporter
+    for machine in prometheus, receiver:
+      machine.wait_until_succeeds(
+        "curl -sf 'http://127.0.0.1:9090/api/v1/query?query=node_exporter_build_info\{instance=\"node:9100\"\}' | "
+        + "jq '.data.result[0].value[1]' | grep '\"1\"'"
+      )
+  '';
+})