Kubernetes ConfigMap Revisions with Pulumi — Pulumi Blog

ConfigMaps in Kubernetes don’t have built-in revision support, which can create challenges when deploying applications with canary strategies.

When using Argo Rollouts with AWS Spot instances, ConfigMap deletions during canary deployments can cause older pods to fail when they try to reload configuration. We solved this by implementing a custom ConfigMap revision system using Pulumi’s ConfigMapPatch and Kubernetes owner references.

The Problem

When deploying applications to Kubernetes using canary strategies with Argo Rollouts, we encountered a specific challenge:

Pulumi ConfigMap replacement behavior: By default, when a ConfigMap’s data changes, Pulumi may replace it rather than update it in place, which for auto-named ConfigMaps results in a new generated name (suffix).
Canary deployment issues: During canary deployments, the old ConfigMap gets deleted, but older pods (especially on AWS Spot instances that can be replaced during canary) may fail to reload
No native revision support: Neither Kubernetes nor Pulumi natively supports ConfigMap revisions like they do for deployments

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The solution: ConfigMap revisions with owner references

Our solution leverages Kubernetes’ garbage collection mechanism by using owner references to tie ConfigMaps to ReplicaSets created during canary deployments.

Pulumi makes this approach practical by letting us express patching logic, owner references, and rollout coordination directly in code, instead of encoding complex behavior in static YAML.

Key components

Pulumi’s ConfigMapPatch: Patches existing ConfigMaps with owner references
ReplicaSet Owner References: Links ConfigMaps to ReplicaSets for automatic cleanup
Kubernetes Garbage Collection: Automatically cleans up ConfigMaps when ReplicaSets are deleted
Retain on Delete: Protects ConfigMaps from immediate deletion during Pulumi updates

Implementation

Here’s how we implemented this solution in our rollout component:

import * as pulumi from "@pulumi/pulumi";
import * as k8s from "@pulumi/kubernetes";
import * as k8sClient from "@kubernetes/client-node";

interface RolloutComponentArgs {
 namespace: string;
 configMapPatch?: boolean;
 kubeconfig: pulumi.Outputany>;
 configMapName: pulumi.Outputstring>;
 rolloutSpec: k8s.types.input.apiextensions.CustomResourceArgs["spec"];
}

export class ConfigMapRevisionRollout extends pulumi.ComponentResource {
 public readonly rollout: k8s.apiextensions.CustomResource;

 constructor(
 name: string,
 args: RolloutComponentArgs,
 opts?: pulumi.ComponentResourceOptions
 ) {
 super("pulumi:component:ConfigMapRevisionRollout", name, {}, opts);

 // Create the Argo Rollout using CustomResource
 this.rollout = new k8s.apiextensions.CustomResource(
 `${name}-rollout`,
 {
 apiVersion: "argoproj.io/v1alpha1",
 kind: "Rollout",
 metadata: {
 name: name,
 namespace: args.namespace,
 },
 spec: args.rolloutSpec,
 },
 { parent: this, ...opts }
 );

 // Apply ConfigMap revision patching if enabled
 if (args.configMapPatch) {
 this.setupConfigMapRevisions(name, args);
 }

 this.registerOutputs({
 rollout: this.rollout,
 });
 }

 private setupConfigMapRevisions(name: string, args: RolloutComponentArgs): void {
 pulumi
 .all([args.kubeconfig, args.configMapName])
 .apply(async ([kubeconfig, configMapName]) => {
 try {
 // Create Server-Side Apply enabled provider
 const ssaProvider = new k8s.Provider(`${name}-ssa-provider`, {
 kubeconfig: JSON.stringify(kubeconfig),
 enableServerSideApply: true,
 });

 // Wait for rollout to stabilize and create ReplicaSets
 await this.waitForRolloutStabilization();

 // Get ReplicaSets associated with this rollout
 const replicaSets = await this.getAssociatedReplicaSets(
 args.namespace,
 configMapName,
 kubeconfig
 );

 if (replicaSets.length === 0) {
 pulumi.log.warn("No ReplicaSets found for ConfigMap patching");
 return;
 }

 // Create owner references for the ConfigMap
 const ownerReferences = replicaSets.map(rs => ({
 apiVersion: "apps/v1",
 kind: "ReplicaSet",
 name: rs.metadata?.name!,
 uid: rs.metadata?.uid!,
 controller: false,
 blockOwnerDeletion: false,
 }));

 // Patch the ConfigMap with owner references
 new k8s.core.v1.ConfigMapPatch(
 `${configMapName}-revision-patch`,
 {
 metadata: {
 name: configMapName,
 namespace: args.namespace,
 ownerReferences: ownerReferences,
 annotations: {
 "pulumi.com/patchForce": "true",
 "configmap.kubernetes.io/revision-managed": "true",
 },
 },
 },
 {
 provider: ssaProvider,
 retainOnDelete: true,
 parent: this,
 }
 );

 pulumi.log.info(
 `Successfully patched ConfigMap ${configMapName} with ${ownerReferences.length} owner references`
 );
 } catch (error) {
 pulumi.log.error(`Failed to setup ConfigMap revisions: ${error}`);
 throw error;
 }
 });
 }

 private async waitForRolloutStabilization(): Promisevoid> {
 // Wait for rollout to create and stabilize ReplicaSets
 // In production, consider using a more sophisticated polling mechanism
 await new Promise(resolve => setTimeout(resolve, 10000));
 }

 private async getAssociatedReplicaSets(
 namespace: string,
 configMapName: string,
 kubeconfig: any
 ): Promisek8sClient.V1ReplicaSet[]> {
 const kc = new k8sClient.KubeConfig();
 kc.loadFromString(JSON.stringify(kubeconfig));

 const appsV1Api = kc.makeApiClient(k8sClient.AppsV1Api);

 try {
 const response = await appsV1Api.listNamespacedReplicaSet(
 namespace,
 undefined, // pretty
 false, // allowWatchBookmarks
 undefined, // continue
 undefined, // fieldSelector
 `configMap=${configMapName}` // labelSelector
 );

 return response.body.items;
 } catch (error) {
 pulumi.log.error(`Failed to list ReplicaSets: ${error}`);
 return [];
 }
 }
}

How do ConfigMap revisions work with Argo Rollouts?

Rollout Creation: When a new rollout is created, Argo Rollouts generates new ReplicaSets for the canary deployment
ConfigMap Patching: Our code waits for the ReplicaSet creation, then patches the ConfigMap with owner references pointing to these ReplicaSets
Garbage Collection: Kubernetes automatically tracks the relationship between ConfigMaps and ReplicaSets
Automatic Cleanup: When ReplicaSets are cleaned up (based on the default 10 revision history), their associated ConfigMaps are also garbage collected

Benefits

Revision Control: ConfigMaps now have revision-like behavior tied to ReplicaSet history
Automatic Cleanup: No manual intervention needed for ConfigMap cleanup
Canary Safety: Old ConfigMaps remain available during canary deployments until ReplicaSets are cleaned up
Spot Instance Resilience: Pods that get replaced during canary deployments can still access their original ConfigMaps

Configuration options

interface RolloutComponentArgs {
 namespace: string;
 configMapPatch?: boolean;
 kubeconfig: pulumi.Outputany>;
 configMapName: pulumi.Outputstring>;
 rolloutSpec: k8s.types.input.apiextensions.CustomResourceArgs["spec"];
}

To enable this feature in your rollout:

import * as pulumi from "@pulumi/pulumi";
import * as k8s from "@pulumi/kubernetes";

// Create your EKS cluster
const cluster = new k8s.Provider("k8s-provider", {
 kubeconfig: clusterKubeconfig,
});

// Create ConfigMap
const appConfig = new k8s.core.v1.ConfigMap("app-config", {
 metadata: {
 name: "my-app-config",
 namespace: "default",
 labels: {
 app: "my-app",
 configMap: "my-app-config", // Important for ReplicaSet selection
 },
 },
 data: {
 "app.properties": "key=value\nother=setting",
 },
}, { provider: cluster });

// Create rollout with ConfigMap revision management
const rollout = new ConfigMapRevisionRollout("my-app", {
 namespace: "default",
 configMapPatch: true,
 kubeconfig: clusterKubeconfig,
 configMapName: appConfig.metadata.name,
 rolloutSpec: {
 replicas: 3,
 selector: {
 matchLabels: { app: "my-app" },
 },
 template: {
 metadata: {
 labels: { app: "my-app" },
 },
 spec: {
 containers: [{
 name: "app",
 image: "nginx:latest",
 volumeMounts: [{
 name: "config",
 mountPath: "/etc/config",
 }],
 }],
 volumes: [{
 name: "config",
 configMap: {
 name: appConfig.metadata.name,
 },
 }],
 },
 },
 strategy: {
 canary: {
 maxSurge: 1,
 maxUnavailable: 0,
 steps: [
 { setWeight: 20 },
 { pause: { duration: "1m" } },
 { setWeight: 50 },
 { pause: { duration: "2m" } },
 ],
 },
 },
 },
});

Key dependencies

The solution uses several key packages:

@pulumi/kubernetes: For Kubernetes resources and ConfigMapPatch
@kubernetes/client-node: For direct Kubernetes API access
Argo Rollouts CRDs installed in your cluster

When should you use this approach?

This pattern is a good fit if you:

Use Argo Rollouts with canary deployments
Rely on ConfigMaps that must remain available across rollout revisions
Run workloads on Spot or preemptible instances
Need automatic cleanup without custom controllers

Conclusion

This approach gives us ConfigMap revision functionality that doesn’t exist natively in Kubernetes or Pulumi. By leveraging Kubernetes’ garbage collection mechanism and Pulumi’s patching capabilities, we created a robust solution for managing ConfigMap lifecycles during canary deployments.

The solution is particularly valuable when:

Running canary deployments with Argo Rollouts
Using AWS Spot instances that can be replaced during deployments
Needing automatic cleanup of old ConfigMaps without manual intervention
Wanting to maintain configuration availability for older pods during deployment transitions

This pattern can be extended to other scenarios where you need revision control for Kubernetes resources that don’t natively support it.

Want to learn how to put these practices into action? Meet us at KubeCon Europe 2026 (Booth 784) or register for our upcoming Zero to Production in Kubernetes workshop.

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