nixos/zrepl: note about systemd unit, add snapshot test

Signed-off-by: Matt Layher <mdlayher@gmail.com>

nixos/modules/services/backup/zrepl.nix

@@ -38,6 +38,9 @@ in
     environment.etc."zrepl/zrepl.yml".source = configFile;
 
     systemd.packages = [ pkgs.zrepl ];
+
+    # Note that pkgs.zrepl copies and adapts the upstream systemd unit, and
+    # the fields defined here only override certain fields from that unit.
     systemd.services.zrepl = {
       requires = [ "local-fs.target" ];
       wantedBy = [ "zfs.target" ];

nixos/tests/all-tests.nix

@@ -590,5 +590,6 @@ in
   zigbee2mqtt = handleTest ./zigbee2mqtt.nix {};
   zoneminder = handleTest ./zoneminder.nix {};
   zookeeper = handleTest ./zookeeper.nix {};
+  zrepl = handleTest ./zrepl.nix {};
   zsh-history = handleTest ./zsh-history.nix {};
 }

nixos/tests/zrepl.nix

@@ -0,0 +1,66 @@
+import ./make-test-python.nix (
+  {
+    nodes.host = {config, pkgs, ...}: {
+      config = {
+        # Prerequisites for ZFS and tests.
+        boot.supportedFilesystems = [ "zfs" ];
+        environment.systemPackages = [ pkgs.zrepl ];
+        networking.hostId = "deadbeef";
+        services.zrepl = {
+          enable = true;
+          settings = {
+            # Enable Prometheus output for status assertions.
+            global.monitoring = [{
+              type = "prometheus";
+              listen = ":9811";
+            }];
+            # Create a periodic snapshot job for an ephemeral zpool.
+            jobs = [{
+              name = "snap_test";
+              type = "snap";
+
+              filesystems."test" = true;
+              snapshotting = {
+                type = "periodic";
+                prefix = "zrepl_";
+                interval = "1s";
+              };
+
+              pruning.keep = [{
+                type = "last_n";
+                count = 8;
+              }];
+            }];
+          };
+        };
+      };
+    };
+
+    testScript = ''
+      start_all()
+
+      with subtest("Wait for zrepl and network ready"):
+          host.wait_for_unit("network-online.target")
+          host.wait_for_unit("zrepl.service")
+
+      with subtest("Create test zpool"):
+          # ZFS requires 64MiB minimum pool size.
+          host.succeed("fallocate -l 64MiB /root/zpool.img")
+          host.succeed("zpool create test /root/zpool.img")
+
+      with subtest("Check for completed zrepl snapshot"):
+          # zrepl periodic snapshot job creates a snapshot with this prefix.
+          host.wait_until_succeeds("zfs list -t snapshot | grep -q zrepl_")
+
+      with subtest("Verify HTTP monitoring server is configured"):
+          out = host.succeed("curl -f localhost:9811/metrics")
+
+          assert (
+              "zrepl_version_daemon" in out
+          ), "zrepl version metric was not found in Prometheus output"
+
+          assert (
+              "zrepl_zfs_snapshot_duration_count{filesystem=\"test\"}" in out
+          ), "zrepl snapshot counter for test was not found in Prometheus output"
+    '';
+  })

pkgs/tools/backup/zrepl/default.nix

@@ -2,6 +2,7 @@
 , buildGoModule
 , fetchFromGitHub
 , makeWrapper
+, nixosTests
 , openssh
 }:
 buildGoModule rec {
@@ -32,11 +33,15 @@ buildGoModule rec {
       --prefix PATH : ${lib.makeBinPath [ openssh ]}
   '';
 
+  passthru.tests = {
+    inherit (nixosTests) zrepl;
+  };
+
   meta = with lib; {
     homepage = "https://zrepl.github.io/";
     description = "A one-stop, integrated solution for ZFS replication";
     platforms = platforms.linux;
     license = licenses.mit;
-    maintainers = with maintainers; [ cole-h danderson ];
+    maintainers = with maintainers; [ cole-h danderson mdlayher ];
   };
 }