feat: read the service clusters a host belongs to (0.10.0)

LinuxDriver mixes in napalm-device-types' ServiceClustersMixin (4.17.0):
get_service_clusters() reads Patroni's members and roles, adguardhome-sync's
origin and replicas and a BunkerWeb worker's manager from the host's own
configuration -- the evidence that two hosts run one service, not merely
answer at one address (NetOrk/netork#1125). _run_service_clusters_command
carries the shared command on an exec channel, root first, like the virtual
IPs' one.

tests/test_linux.py

@@ -1721,6 +1721,44 @@ class TestGetVirtualIps:
         assert plain.startswith("sh -c '")
 
 
+# ---------------------------------------------------------------------------
+# get_service_clusters (napalm-device-types ServiceClustersMixin)
+# ---------------------------------------------------------------------------
+
+_CLUSTERS = (
+    "SVCC_BEGIN\n[systemd]\n[patroni patroni.service]\nactive active\nscope netork-db\n"
+    "name db-01\nrestapi 10.7.234.12:8008\nrest-unreachable\n[no-docker]\nSVCC_END\n"
+)
+
+
+class TestGetServiceClusters:
+    """The same template as get_virtual_ips: an exec channel, root first."""
+
+    _exec = staticmethod(TestGetVirtualIps._exec)
+
+    def test_it_reads_with_the_shared_command_on_an_exec_channel(self, driver):
+        from napalm_device_types import ServiceClustersMixin
+
+        assert isinstance(driver, ServiceClustersMixin)
+        calls = self._exec(driver, (_CLUSTERS, "", 0))
+
+        reading = driver.get_service_clusters()
+
+        assert reading["patroni"][0]["cluster"] == "netork-db"
+        [(command, privileged)] = calls
+        assert privileged is True
+        assert command.startswith("sh -c '")
+        driver._device.send_command.assert_not_called()
+
+    def test_when_sudo_refuses_it_reads_what_the_user_may_see(self, driver):
+        calls = self._exec(driver, ("", "sudo: a password is required\n", 1), (_CLUSTERS, "", 0))
+
+        reading = driver.get_service_clusters()
+
+        assert reading["bunkerweb"] == []
+        assert [privileged for _, privileged in calls] == [True, False]
+
+
 class TestHardensItsSshServer:
     """A stock Linux host runs a stock OpenSSH: the hardening netOrk offers for
     ssh-audit findings comes from napalm-device-types, carried over run_command