Flagger vs Kargo

Flagger is a self-hosted Kubernetes operator that automates progressive delivery for applications running on Kubernetes. It gradually shifts traffic to a new version while checking measures such as HTTP or gRPC request success and latency. Deployment approaches include canary releases, A/B testing, and blue/green deployments, routed through an ingress controller or a service mesh compatible with the Kubernetes Gateway API. Built-in checks cover HTTP request success rate and duration; teams can add custom metrics and webhooks for acceptance tests, load tests, or other validation. Release analysis can query systems including Prometheus, Datadog, CloudWatch, New Relic, Graphite, Dynatrace, InfluxDB, and Google Cloud Monitoring. If SLO analysis detects a performance drop, Flagger rolls back the release automatically. Manual controls allow approval, pausing, or resuming deployments, and notifications can go to Slack, Microsoft Teams, Discord, or Rocket. It is configured through Kubernetes custom resources, works with Kubernetes-compatible CI/CD solutions, and can be used with Flux for GitOps canary pipelines. Flagger is Apache 2.0 licensed and free.

Kargo is an open-source continuous promotion orchestration layer for moving applications through deployment stages in Kubernetes environments. It complements Argo CD, with customizable pipelines for advancing changes from one environment to another and a view of changes across environments. Kargo tracks updates from Git artifacts, container images, Helm charts, and other artifacts. Verification checks can run at stages before an artifact advances downstream. Documented promotion steps include Git operations, Helm, Kustomize, Argo CD, and HTTP requests to external services. Kargo Enterprise additionally lists Jira, ServiceNow, JFrog Evidence, GitHub Actions, and Slack or email notifications, and can automatically return a stage to its last stable artifact when verification fails. The open-source distribution uses the Apache 2.0 license. A basic installation requires a Kubernetes cluster, and the documentation says Kargo works best paired with Argo CD. Its default configuration is suitable only for trying it in a local cluster that is not internet-facing. The open-source distribution has no time- or severity-bound backport guarantee for security fixes. Akuity Pro, including one Kargo instance, is listed at $495 a month; Enterprise pricing is available by contacting sales.