tests: check CoreDNS via pod state instead of host process

tests/test-simple.py

@@ -2,7 +2,6 @@
 import time
 import requests
 import os.path
-
 import utils
 
 
@@ -136,15 +135,16 @@ def test_microk8s_services_running(self):
         assert running_node_services == set(node_services), "Not all node services are running"
 
     def test_microk8s_stop_start(self):
-        coredns_procs = utils._get_process("coredns")
-        assert len(coredns_procs) > 0, "Expected to find a coredns process running."
+        assert (
+            utils.is_coredns_running()
+        ), "Expected CoreDNS pod to be running before microk8s stop."
 
         utils.run_until_success("/snap/bin/microk8s.stop", timeout_insec=180)
 
-        new_coredns_procs = utils._get_process("coredns")
-        assert len(new_coredns_procs) == 0, "coredns found still running after microk8s stop."
+        assert not utils.is_coredns_running(), "CoreDNS pod still running after microk8s stop."
 
         utils.run_until_success("/snap/bin/microk8s.start", timeout_insec=180)
 
-        new_coredns_procs = utils._get_process("coredns")
-        assert len(new_coredns_procs) > 0, "Expected to find a new coredns process running."
+        assert (
+            utils.is_coredns_running()
+        ), "Expected CoreDNS pod to be running after microk8s start."

tests/utils.py

@@ -4,6 +4,7 @@
 import yaml
 import platform
 import psutil
+import subprocess
 from subprocess import check_output, CalledProcessError, check_call
 
 
@@ -90,6 +91,31 @@ def kubectl_get(target, timeout_insec=300):
     return yaml.safe_load(output)
 
 
+def is_coredns_running():
+    cmd = [
+        "/snap/bin/microk8s",
+        "kubectl",
+        "get",
+        "pods",
+        "-n",
+        "kube-system",
+        "-l",
+        "k8s-app=kube-dns",
+        "--no-headers",
+    ]
+
+    result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+
+    if result.returncode != 0:
+        return False
+
+    for line in result.stdout.splitlines():
+        if "Running" in line:
+            return True
+
+    return False
+
+
 def wait_for_pod_state(
     pod, namespace, desired_state, desired_reason=None, label=None, timeout_insec=600
 ):