Alpine: fix location of dhclient leases file (#4782)

PR #4683 changes missed Alpine. This PR addresses this.

cloudinit/distros/alpine.py

@@ -33,6 +33,10 @@ class Distro(distros.Distro):
     renderer_configs = {
         "eni": {"eni_path": network_conf_fn, "eni_header": NETWORK_FILE_HEADER}
     }
+    # Alpine stores dhclient leases at following location:
+    # /var/lib/dhcp/dhclient.leases
+    dhclient_lease_directory = "/var/lib/dhcp"
+    dhclient_lease_file_regex = r"dhclient\.leases"
 
     def __init__(self, name, cfg, paths):
         distros.Distro.__init__(self, name, cfg, paths)

tests/unittests/net/test_dhcp.py

@@ -7,7 +7,7 @@
 import pytest
 import responses
 
-from cloudinit.distros import amazon, centos, debian, freebsd, rhel
+from cloudinit.distros import alpine, amazon, centos, debian, freebsd, rhel
 from cloudinit.net.dhcp import (
     DHCLIENT_FALLBACK_LEASE_DIR,
     InvalidDHCPLeaseFileError,
@@ -1206,6 +1206,28 @@ def test_get_latest_lease_freebsd(self, *_):
             ),
         )
 
+    @mock.patch(
+        "os.listdir",
+        return_value=(
+            "some_file",
+            # alpine style lease file
+            "dhclient.leases",
+            "some_other_file",
+        ),
+    )
+    @mock.patch("os.path.getmtime", return_value=123.45)
+    def test_get_latest_lease_alpine(self, *_):
+        """
+        Test that an alpine style lease has been found
+        """
+        self.assertEqual(
+            "/var/lib/dhcp/dhclient.leases",
+            IscDhclient.get_latest_lease(
+                alpine.Distro.dhclient_lease_directory,
+                alpine.Distro.dhclient_lease_file_regex,
+            ),
+        )
+
     @mock.patch(
         "os.listdir",
         return_value=(