Execute Vagrant cluster in CI (#57)

vagrant/test_cluster.py

@@ -0,0 +1,114 @@
+#!/usr/bin/env python3
+
+# Perform a few tests on a cluster created with this playbook.
+# To simplify test execution, the scripts does not depend on any third-party
+# packages, only the Python standard library.
+
+import json
+import subprocess
+import unittest
+from pathlib import Path
+from time import sleep
+from warnings import warn
+
+
+VAGRANT_DIR = Path(__file__).parent.absolute()
+PLAYBOOK_DIR = VAGRANT_DIR.parent.absolute()
+
+
+class TestK3sCluster(unittest.TestCase):
+    def _kubectl(self, args: str, json_out: bool = True) -> dict | None:
+        cmd = "kubectl"
+        if json_out:
+            cmd += " -o json"
+        cmd += f" {args}"
+
+        result = subprocess.run(cmd, capture_output=True, shell=True, check=True)
+
+        if json_out:
+            return json.loads(result.stdout)
+        else:
+            return None
+
+    def _curl(self, url: str) -> str:
+        options = [
+            "--silent",  # no progress info
+            "--show-error",  # ... but errors should still be shown
+            "--fail",  # set exit code on error
+            "--location",  # follow redirects
+        ]
+        cmd = f'curl {" ".join(options)} "{url}"'
+
+        result = subprocess.run(cmd, capture_output=True, shell=True, check=True)
+        output = result.stdout.decode("utf-8")
+        return output
+
+    def _apply_manifest(self, manifest_file: Path) -> dict:
+        apply_result = self._kubectl(
+            f'apply --filename="{manifest_file}" --cascade="background"'
+        )
+        self.addCleanup(
+            lambda: self._kubectl(
+                f'delete --filename="{manifest_file}"',
+                json_out=False,
+            )
+        )
+        return apply_result
+
+    @staticmethod
+    def _retry(function, retries: int = 5, seconds_between_retries=1):
+        for retry in range(1, retries + 1):
+            try:
+                return function()
+            except Exception as exc:
+                if retry < retries:
+                    sleep(seconds_between_retries)
+                    continue
+                else:
+                    raise exc
+
+    def _get_load_balancer_ip(
+        self,
+        service: str,
+        namespace: str = "default",
+    ) -> str | None:
+        svc_description = self._kubectl(
+            f'get --namespace="{namespace}" service "{service}"'
+        )
+        ip = svc_description["status"]["loadBalancer"]["ingress"][0]["ip"]
+        return ip
+
+    def test_nodes_exist(self):
+        out = self._kubectl("get nodes")
+        node_names = {item["metadata"]["name"] for item in out["items"]}
+        self.assertEqual(
+            node_names,
+            {"control1", "control2", "control3", "node1", "node2"},
+        )
+
+    def test_ip_address_pool_exists(self):
+        out = self._kubectl("get --all-namespaces IpAddressPool")
+        pools = out["items"]
+        self.assertGreater(len(pools), 0)
+
+    def test_nginx_example_page(self):
+        # Deploy the manifests to the cluster
+        deployment = self._apply_manifest(PLAYBOOK_DIR / "example" / "deployment.yml")
+        service = self._apply_manifest(PLAYBOOK_DIR / "example" / "service.yml")
+
+        # Assert that the dummy page is available
+        metallb_ip = self._retry(
+            lambda: self._get_load_balancer_ip(service["metadata"]["name"])
+        )
+        # Now that an IP address was assigned, let's reload the service description:
+        service = self._kubectl(f'get service "{service["metadata"]["name"]}"')
+        metallb_port = service["spec"]["ports"][0]["port"]
+
+        response_body = self._retry(
+            lambda: self._curl(f"http://{metallb_ip}:{metallb_port}/")
+        )
+        self.assertIn("Welcome to nginx!", response_body)
+
+
+if __name__ == "__main__":
+    unittest.main()