Adds NFS CSI plugin integration test (#7)

The Helm chart depends on a few other CSI components. We have rocks for
these, and we'll be using them in the helm chart as well.

The test will also check the Pod probes to make sure that the service is
up, without waiting for Kubernetes to do the check.

The test will also spawn a NFS server, and create an NGINX Pod requiring
a NFS volume.

tests/integration/conftest.py

@@ -0,0 +1,5 @@
+#
+# Copyright 2024 Canonical, Ltd.
+#
+
+pytest_plugins = ["k8s_test_harness.plugin"]

tests/integration/test_csi_driver_nfs.py

@@ -2,7 +2,87 @@
 # Copyright 2024 Canonical, Ltd.
 #
 
+import logging
+import pathlib
 
-def test_csi_driver_nfs_integration():
-    """Test NFS CSI driver rock."""
-    pass
+from k8s_test_harness import harness
+from k8s_test_harness.util import constants, env_util, exec_util, k8s_util
+
+LOG = logging.getLogger(__name__)
+
+DIR = pathlib.Path(__file__).absolute().parent
+MANIFESTS_DIR = DIR / ".." / "templates"
+
+
+def _get_nfsplugin_csi_helm_cmd(version: str):
+    rock = env_util.get_build_meta_info_for_rock_version("nfsplugin", version, "amd64")
+
+    images = [
+        k8s_util.HelmImage(rock.image, subitem="nfs"),
+    ]
+
+    set_configs = [
+        "externalSnapshotter.enabled=true",
+    ]
+
+    return k8s_util.get_helm_install_command(
+        "csi-driver-nfs",
+        "csi-driver-nfs",
+        repository="https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/charts",
+        chart_version="v4.7.0",
+        images=images,
+        set_configs=set_configs,
+    )
+
+
+def test_nfsplugin_integration(function_instance: harness.Instance):
+    helm_command = _get_nfsplugin_csi_helm_cmd("4.7.0")
+    function_instance.exec(helm_command)
+
+    # wait for all the components to become active.
+    k8s_util.wait_for_daemonset(function_instance, "csi-nfs-node", "kube-system")
+    k8s_util.wait_for_deployment(function_instance, "csi-nfs-controller", "kube-system")
+    k8s_util.wait_for_deployment(
+        function_instance, "snapshot-controller", "kube-system"
+    )
+
+    # call the nfsplugin's liveness probes to check that they're running as intended.
+    for port in [29652, 29653]:
+        # It has hostNetwork=true, which means that curling localhost should work.
+        exec_util.stubbornly(retries=5, delay_s=5).on(function_instance).exec(
+            ["curl", f"http://localhost:{port}/healthz"]
+        )
+
+    # Deploy a NFS server and an nginx Pod with a NFS volume attached.
+    for item in ["nfs-server.yaml", "nginx-pod.yaml"]:
+        manifest = MANIFESTS_DIR / item
+        function_instance.exec(
+            ["k8s", "kubectl", "apply", "-f", "-"],
+            input=pathlib.Path(manifest).read_bytes(),
+        )
+
+    # Expect the Pod to become ready, and that it has the volume attached.
+    k8s_util.wait_for_deployment(function_instance, "nfs-server")
+    k8s_util.wait_for_resource(
+        function_instance,
+        "pod",
+        "nginx-nfs-example",
+        condition=constants.K8S_CONDITION_READY,
+    )
+
+    process = function_instance.exec(
+        [
+            "k8s",
+            "kubectl",
+            "exec",
+            "nginx-nfs-example",
+            "--",
+            "bash",
+            "-c",
+            "findmnt /var/www -o TARGET,SOURCE,FSTYPE",
+        ],
+        capture_output=True,
+        text=True,
+    )
+
+    assert "/var/www nfs-server.default.svc.cluster.local:/ nfs4" in process.stdout

tests/templates/nfs-server.yaml

@@ -0,0 +1,62 @@
+# from: https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/deploy/example/nfs-provisioner/nfs-server.yaml
+---
+kind: Service
+apiVersion: v1
+metadata:
+  name: nfs-server
+  namespace: default
+  labels:
+    app: nfs-server
+spec:
+  type: ClusterIP  # use "LoadBalancer" to get a public ip
+  selector:
+    app: nfs-server
+  ports:
+    - name: tcp-2049
+      port: 2049
+      protocol: TCP
+    - name: udp-111
+      port: 111
+      protocol: UDP
+---
+kind: Deployment
+apiVersion: apps/v1
+metadata:
+  name: nfs-server
+  namespace: default
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: nfs-server
+  template:
+    metadata:
+      name: nfs-server
+      labels:
+        app: nfs-server
+    spec:
+      nodeSelector:
+        "kubernetes.io/os": linux
+      containers:
+        - name: nfs-server
+          image: itsthenetwork/nfs-server-alpine:latest
+          env:
+            - name: SHARED_DIRECTORY
+              value: "/exports"
+          volumeMounts:
+            - mountPath: /exports
+              name: nfs-vol
+          securityContext:
+            privileged: true
+          ports:
+            - name: tcp-2049
+              containerPort: 2049
+              protocol: TCP
+            - name: udp-111
+              containerPort: 111
+              protocol: UDP
+      volumes:
+        - name: nfs-vol
+          hostPath:
+            path: /nfs-vol  # modify this to specify another path to store nfs share data
+            type: DirectoryOrCreate

tests/templates/nginx-pod.yaml

@@ -0,0 +1,60 @@
+# from: https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/deploy/example/nfs-provisioner/nginx-pod.yaml
+---
+apiVersion: v1
+kind: PersistentVolume
+metadata:
+  annotations:
+    pv.kubernetes.io/provisioned-by: nfs.csi.k8s.io
+  name: pv-nginx
+  namespace: default
+spec:
+  capacity:
+    storage: 10Gi
+  accessModes:
+    - ReadWriteOnce
+  persistentVolumeReclaimPolicy: Delete
+  mountOptions:
+    - nfsvers=4.1
+  csi:
+    driver: nfs.csi.k8s.io
+    # volumeHandle format: {nfs-server-address}#{sub-dir-name}#{share-name}
+    # make sure this value is unique for every share in the cluster
+    volumeHandle: nfs-server.default.svc.cluster.local/share##
+    volumeAttributes:
+      server: nfs-server.default.svc.cluster.local
+      share: /
+---
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: pvc-nginx
+  namespace: default
+spec:
+  accessModes:
+    - ReadWriteOnce
+  resources:
+    requests:
+      storage: 10Gi
+  volumeName: pv-nginx
+  storageClassName: ""
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: nginx-nfs-example
+  namespace: default
+spec:
+  containers:
+    - image: nginx
+      name: nginx
+      ports:
+        - containerPort: 80
+          protocol: TCP
+      volumeMounts:
+        - mountPath: /var/www
+          name: pvc-nginx
+          readOnly: false
+  volumes:
+    - name: pvc-nginx
+      persistentVolumeClaim:
+        claimName: pvc-nginx