Add integrated test for log rotation

This is the follow-up to [this PR][0].

[0]: #308

vm.nix

@@ -3,7 +3,50 @@
 testers.nixosTest {
   name = "vm-test";
 
-  nodes.server = { ... }: {
+  nodes.server = { pkgs, ... }: {
+
+    environment = {
+      etc = {
+
+        "nc.sh" = {
+          text = ''
+            #!/bin/sh
+            while true; do
+              ${pkgs.netcat}/bin/nc -l "$PORT" <<'EOF'
+            HTTP/1.1 200 OK
+            Content-Length: 13
+            Connection: close
+
+            Hello, world!
+            EOF
+            done
+          '';
+          mode = "0755";
+        };
+
+        "keter.yaml".text = ''
+          stanzas:
+            - type: webapp
+              exec: ../nc.sh
+              hosts:
+                - localhost
+        '';
+
+        "deploy.sh" = {
+          text = ''
+            mkdir -p /tmp/bundle/config
+            cp /etc/nc.sh /tmp/bundle/nc.sh
+            cp /etc/keter.yaml /tmp/bundle/config/keter.yaml
+            tar -C /tmp/bundle -czvf /tmp/nc.keter .
+            cp /tmp/nc.keter /opt/keter/incoming
+          '';
+          mode = "0755";
+        };
+
+      };
+
+      systemPackages = [ pkgs.netcat ];
+    };
 
     imports = [
       ./keter.nix
@@ -19,7 +62,7 @@ testers.nixosTest {
       package = self.packages.x86_64-linux.keter;
       globalKeterConfig = ''
         root: /opt/keter
-        rotate-logs: false
+        rotate-logs: true
         listeners:
           - host: "*4"
             port: 80
@@ -32,6 +75,12 @@ testers.nixosTest {
     server.start()
     server.wait_for_unit("keter-ng.service")
     server.wait_for_open_port(80)
-    server.succeed("curl localhost")
+    server.succeed(". /etc/deploy.sh")
+    server.sleep(10)
+    server.succeed("curl localhost | grep 'Hello, world!'")
+    server.succeed("! grep -q 'file is locked' /opt/keter/log/keter.log")
+    server.succeed("touch /opt/keter/incoming/nc.keter")
+    server.sleep(10)
+    server.succeed("! grep -q 'file is locked' /opt/keter/log/keter.log")
   '';
 }