feat: Adds the ability to replace webhooks on startup and configure the webhooks when creating (#538)

Fixes #525 and #532

Author: ecooke-macu

src/KubeOps/Operator/Commands/Management/Webhooks/Install.cs

@@ -43,6 +43,13 @@ public Install(
         LongName = "ca-certs")]
     public string CaCertificatesPath { get; set; } = "/ca";
 
+    [Option(
+        Description =
+            "If specified and set to true it will replace already existing webhooks",
+        ShortName = "r",
+        LongName = "replace-existing")]
+    public bool ReplaceExistingWebhooks { get; set; }
+
     public async Task<int> OnExecuteAsync(CommandLineApplication app)
     {
         var client = app.GetRequiredService<IKubernetesClient>();
@@ -116,7 +123,27 @@ await client.Create(
             validatorConfig.Metadata.OwnerReferences = new List<V1OwnerReference> { deployment.MakeOwnerReference(), };
         }
 
-        await client.Save(validatorConfig);
+        if (ReplaceExistingWebhooks)
+        {
+            // var existingItems = await client.List<V1ValidatingWebhookConfiguration>();
+            // var existingItem = existingItems.FirstOrDefault(item => item.Name() == validatorConfig.Name());
+            var existingItem = await client.Get<V1ValidatingWebhookConfiguration>(validatorConfig.Name());
+            if (existingItem != null)
+            {
+                await app.Out.WriteLineAsync("Validator existed, updating.");
+                await client.Update(existingItem);
+            }
+            else
+            {
+                await app.Out.WriteLineAsync("Validator didn't exist, creating.");
+                await client.Save(validatorConfig);
+            }
+        }
+        else
+        {
+            await app.Out.WriteLineAsync("Not updating validator, attempting to save.");
+            await client.Save(validatorConfig);
+        }
 
         await app.Out.WriteLineAsync("Create mutator definition.");
         var mutatorConfig = _mutatingWebhookConfigurationBuilder.BuildWebhookConfiguration(webhookConfig);
@@ -125,7 +152,25 @@ await client.Create(
             mutatorConfig.Metadata.OwnerReferences = new List<V1OwnerReference> { deployment.MakeOwnerReference(), };
         }
 
-        await client.Save(mutatorConfig);
+        if (ReplaceExistingWebhooks)
+        {
+            var existingItem = await client.Get<V1MutatingWebhookConfiguration>(mutatorConfig.Name());
+            if (existingItem != null)
+            {
+                await app.Out.WriteLineAsync("Mutator existed, updating.");
+                await client.Update(existingItem);
+            }
+            else
+            {
+                await app.Out.WriteLineAsync("Mutator didn't exist, creating.");
+                await client.Save(mutatorConfig);
+            }
+        }
+        else
+        {
+            await app.Out.WriteLineAsync("Not updating mutator, attempting to save.");
+            await client.Save(mutatorConfig);
+        }
 
         await app.Out.WriteLineAsync("Installed webhook service and admission configurations.");
 

src/KubeOps/Operator/Webhooks/IConfigurableMutationWebhook.cs

@@ -0,0 +1,15 @@
+using k8s.Models;
+
+namespace KubeOps.Operator.Webhooks;
+
+/// <summary>
+/// Implement this interface to configure the MutatingWebhook object before it is applied to Kubernetes.
+/// </summary>
+public interface IConfigurableMutationWebhook
+{
+    /// <summary>
+    /// Called when building the MutatingWebhook to allow further customizations before it is applied.
+    /// </summary>
+    /// <param name="webhook">The MutatingWebhook that will be applied.</param>
+    void Configure(V1MutatingWebhook webhook);
+}

src/KubeOps/Operator/Webhooks/IConfigurableValidationWebhook.cs

@@ -0,0 +1,15 @@
+using k8s.Models;
+
+namespace KubeOps.Operator.Webhooks;
+
+/// <summary>
+/// Implement this interface to configure the ValidatingWebhook object before it is applied to Kubernetes.
+/// </summary>
+public interface IConfigurableValidationWebhook
+{
+    /// <summary>
+    /// Called when building the ValidatingWebhook to allow further customizations before it is applied.
+    /// </summary>
+    /// <param name="webhook">The ValidatingWebhook that will be applied.</param>
+    void Configure(V1ValidatingWebhook webhook);
+}

src/KubeOps/Operator/Webhooks/MutatingWebhookBuilder.cs

@@ -1,4 +1,4 @@
-using System.Reflection;
+using System.Reflection;
 using k8s.Models;
 using KubeOps.KubernetesClient.Entities;
 using KubeOps.Operator.Builder;
@@ -60,7 +60,7 @@ public List<V1MutatingWebhook> BuildWebhooks(WebhookConfig webhookConfig)
 
                     var crd = entityType.ToEntityDefinition();
 
-                    return new V1MutatingWebhook
+                    var webhook = new V1MutatingWebhook
                     {
                         Name = name.TrimWebhookName(),
                         AdmissionReviewVersions = new[] { "v1" },
@@ -79,6 +79,13 @@ public List<V1MutatingWebhook> BuildWebhooks(WebhookConfig webhookConfig)
                         },
                         ClientConfig = clientConfig,
                     };
+
+                    if (instance is IConfigurableMutationWebhook configurable)
+                    {
+                        configurable.Configure(webhook);
+                    }
+
+                    return webhook;
                 })
             .ToList();
     }

src/KubeOps/Operator/Webhooks/ValidatingWebhookBuilder.cs

@@ -1,4 +1,4 @@
-using System.Reflection;
+using System.Reflection;
 using k8s.Models;
 using KubeOps.KubernetesClient.Entities;
 using KubeOps.Operator.Builder;
@@ -60,7 +60,7 @@ public List<V1ValidatingWebhook> BuildWebhooks(WebhookConfig webhookConfig)
 
                     var crd = entityType.ToEntityDefinition();
 
-                    return new V1ValidatingWebhook
+                    var webhook = new V1ValidatingWebhook
                     {
                         Name = name.TrimWebhookName(),
                         AdmissionReviewVersions = new[] { "v1" },
@@ -79,6 +79,13 @@ public List<V1ValidatingWebhook> BuildWebhooks(WebhookConfig webhookConfig)
                         },
                         ClientConfig = clientConfig,
                     };
+
+                    if (instance is IConfigurableValidationWebhook configurable)
+                    {
+                        configurable.Configure(webhook);
+                    }
+
+                    return webhook;
                 })
             .ToList();
     }