feat: zero downtime readiness

plugins/contrib/kontinuous.yaml

@@ -33,6 +33,8 @@ patches:
     enabled: false
   privateImages:
     enabled: false
+  zeroDowntimeReadiness:
+    enabled: false
 
 validators:
   rancherProjectId:

plugins/contrib/patches/70-zero-downtime-readiness.js

@@ -0,0 +1,86 @@
+module.exports = function updateDeploymentManifests(manifests, options = {}) {
+  // Set default values for options if not provided
+  const {
+    initialDelaySeconds = 5,
+    periodSeconds = 5,
+    gracefulShutdownSeconds = 30, // Default graceful shutdown time
+    disableAnnotation = "kontinuous/plugin.zeroDowntimeHandled",
+  } = options
+
+  manifests.forEach((manifest) => {
+    // Check if the resource is a Deployment and doesn't have the disable annotation
+    if (
+      manifest.kind === "Deployment" &&
+      (!manifest.metadata.annotations ||
+        manifest.metadata.annotations[disableAnnotation] !== "true")
+    ) {
+      // Ensure metadata, spec, and template sections exist
+      manifest.metadata.annotations = manifest.metadata.annotations || {}
+      manifest.spec = manifest.spec || {}
+      manifest.spec.template = manifest.spec.template || {}
+      manifest.spec.template.spec = manifest.spec.template.spec || {
+        containers: [],
+        volumes: [],
+      }
+
+      // Setup the postStart and preStop lifecycle hooks and readiness probe
+      manifest.spec.template.spec.containers.forEach((container) => {
+        // Setup lifecycle hooks
+        container.lifecycle = {
+          postStart: {
+            exec: {
+              // Command to create the readiness file
+              command: [
+                "sh",
+                "-c",
+                "touch /var/run/readiness-check/readiness-file",
+              ],
+            },
+          },
+          preStop: {
+            exec: {
+              // Adding a sleep of gracefulShutdownSeconds before removing the readiness file
+              command: [
+                "sh",
+                "-c",
+                `sleep ${gracefulShutdownSeconds}; rm -f /var/run/readiness-check/readiness-file`,
+              ],
+            },
+          },
+        }
+
+        // Setup readiness probe
+        container.readinessProbe = {
+          exec: {
+            command: ["cat", "/var/run/readiness-check/readiness-file"],
+          },
+          initialDelaySeconds,
+          periodSeconds,
+        }
+
+        // Define a unique and precise mount path
+        const mountPath = "/var/run/readiness-check"
+        const uniqueVolumeName = "readiness-check-volume"
+        container.volumeMounts = container.volumeMounts || []
+        container.volumeMounts.push({
+          name: uniqueVolumeName,
+          mountPath,
+        })
+      })
+
+      // Ensure the volume does not conflict and is added to the pod spec
+      if (
+        !manifest.spec.template.spec.volumes.some(
+          (v) => v.name === "readiness-check-volume"
+        )
+      ) {
+        manifest.spec.template.spec.volumes.push({
+          name: "readiness-check-volume",
+          emptyDir: {},
+        })
+      }
+    }
+  })
+
+  return manifests
+}

plugins/fabrique/kontinuous.yaml

@@ -21,6 +21,9 @@ dependencies:
             buildkitSvcCount: 6
 
     patches:
+      zeroDowntimeReadiness:
+        # enabled: true
+        enabled: false
       certs:
         enabled: true
         options: