cluster/services/patroni/default.nix

@@ -4,6 +4,7 @@
   imports = [
     ./options.nix
     ./incandescence.nix
+    ./simulacrum/test-data.nix
   ];
 
   links = {
@@ -36,6 +37,10 @@
       PATRONI_REWIND_PASSWORD = default;
       metricsCredentials.nodes = nodes.worker;
     };
-    simulacrum.deps = [ "consul" "incandescence" "locksmith" ];
+    simulacrum = {
+      enable = true;
+      deps = [ "consul" "incandescence" "locksmith" ];
+      settings = ./simulacrum/test.nix;
+    };
   };
 }

cluster/services/patroni/simulacrum/test-data.nix

@@ -0,0 +1,14 @@
+{ config, lib, ... }:
+{
+  patroni = lib.mkIf config.simulacrum {
+    databases = config.lib.forService "patroni" {
+      testdb.owner = "testuser";
+    };
+    users = config.lib.forService "patroni" {
+      testuser.locksmith = {
+        nodes = config.services.patroni.nodes.haproxy;
+        format = "pgpass";
+      };
+    };
+  };
+}

cluster/services/patroni/simulacrum/test.nix

@@ -0,0 +1,91 @@
+{ cluster, ... }:
+
+let
+  clusterName = "poseidon";
+  link = cluster.config.links.patroni-pg-access;
+in
+{
+  defaults = { depot, pkgs, ... }: {
+    environment.systemPackages = [
+      pkgs.jq
+      depot.packages.postgresql
+    ];
+    services.patroni.settings.postgresql.pg_hba = [
+      "host postgres postgres 0.0.0.0/0 trust"
+    ];
+  };
+
+  # taken from https://github.com/phfroidmont/nixpkgs/blob/patroni-module/nixos/tests/patroni.nix
+  testScript = ''
+    import json
+    nodeNames = json.loads('${builtins.toJSON cluster.config.services.patroni.nodes.worker}')
+    clientNames = json.loads('${builtins.toJSON cluster.config.services.patroni.nodes.haproxy}')
+    nodes = [ n for n in machines if n.name in nodeNames ]
+    clients = [ n for n in machines if n.name in clientNames ]
+
+    def booted(nodes):
+      return filter(lambda node: node.booted, nodes)
+
+    def wait_for_all_nodes_ready(expected_replicas=2):
+        booted_nodes = booted(nodes)
+        for node in booted_nodes:
+            node.wait_for_unit("patroni.service")
+            print(node.succeed("patronictl list ${clusterName}"))
+            node.wait_until_succeeds(f"[ $(patronictl list -f json ${clusterName} | jq 'length') == {expected_replicas + 1} ]")
+            node.wait_until_succeeds("[ $(patronictl list -f json ${clusterName} | jq 'map(select(.Role | test(\"^Leader$\"))) | map(select(.State | test(\"^running$\"))) | length') == 1 ]")
+            node.wait_until_succeeds(f"[ $(patronictl list -f json ${clusterName} | jq 'map(select(.Role | test(\"^Replica$\"))) | map(select(.State | test(\"^streaming$\"))) | length') == {expected_replicas} ]")
+            print(node.succeed("patronictl list ${clusterName}"))
+        for client in booted(clients):
+            client.wait_until_succeeds("psql -h ${link.ipv4} -p ${link.portStr} -U postgres --command='select 1;'")
+
+    def run_dummy_queries():
+        for client in booted(clients):
+            client.succeed("psql -h ${link.ipv4} -p ${link.portStr} -U postgres --pset='pager=off' --tuples-only --command='insert into dummy(val) values (101);'")
+            client.succeed("test $(psql -h ${link.ipv4} -p ${link.portStr} -U postgres --pset='pager=off' --tuples-only --command='select val from dummy where val = 101;') -eq 101")
+            client.succeed("psql -h ${link.ipv4} -p ${link.portStr} -U postgres --pset='pager=off' --tuples-only --command='delete from dummy where val = 101;'")
+
+    start_all()
+
+    with subtest("should bootstrap a new patroni cluster"):
+        wait_for_all_nodes_ready()
+
+    with subtest("should be able to insert and select"):
+        booted_clients = list(booted(clients))
+        booted_clients[0].succeed("psql -h ${link.ipv4} -p ${link.portStr} -U postgres --command='create table dummy as select * from generate_series(1, 100) as val;'")
+        for client in booted_clients:
+            client.succeed("test $(psql -h ${link.ipv4} -p ${link.portStr} -U postgres --pset='pager=off' --tuples-only --command='select count(distinct val) from dummy;') -eq 100")
+
+    with subtest("should restart after all nodes are crashed"):
+        for node in nodes:
+            node.crash()
+        for node in nodes:
+            node.start()
+        wait_for_all_nodes_ready()
+
+    with subtest("should be able to run queries while any one node is crashed"):
+        masterNodeName = nodes[0].succeed("patronictl list -f json ${clusterName} | jq '.[] | select(.Role | test(\"^Leader$\")) | .Member' -r").strip()
+        masterNodeIndex = next((i for i, v in enumerate(nodes) if v.name == masterNodeName))
+
+        # Move master node at the end of the list to avoid multiple failovers (makes the test faster and more consistent)
+        nodes.append(nodes.pop(masterNodeIndex))
+
+        for node in nodes:
+            node.crash()
+            wait_for_all_nodes_ready(1)
+
+            # Execute some queries while a node is down.
+            run_dummy_queries()
+
+            # Restart crashed node.
+            node.start()
+            wait_for_all_nodes_ready()
+
+            # Execute some queries with the node back up.
+            run_dummy_queries()
+
+    with subtest("should create databases and users via incandescence"):
+        for client in clients:
+            client.succeed(f"PGPASSFILE=/run/locksmith/patroni-testuser psql -h ${link.ipv4} -p ${link.portStr} -U testuser -d testdb --command='create table test_table_{client.name} as select * from generate_series(1, 10) as val;'")
+            client.fail("PGPASSFILE=/run/locksmith/patroni-testuser psql -h ${link.ipv4} -p ${link.portStr} -U testuser -d postgres --command='select * from dummy;'")
+  '';
+}