Flagger
Flagger is a self-hosted Kubernetes operator that automates progressive delivery for applications running on Kubernetes.
What Flagger is
Flagger is a self-hosted Kubernetes operator that automates progressive delivery for applications running on Kubernetes. It gradually moves traffic to a new version while checking metrics such as HTTP or gRPC request success and latency. Teams can use it for canary releases, A/B testing or blue/green deployments, with routing through an ingress controller or a service mesh compatible with the Kubernetes Gateway API. Built-in checks cover HTTP success rate and request duration; custom metrics and webhooks can add acceptance tests, load tests or other validation. If SLO analysis detects a performance decline, Flagger can roll back the release automatically. It can query systems including Prometheus, Datadog, CloudWatch, New Relic, Graphite, Dynatrace, InfluxDB and Google Cloud Monitoring, and can notify teams through Slack, Microsoft Teams, Discord or Rocket. Deployments can also have manual approval, pause and resume controls. Configuration uses Kubernetes custom resources, and Flagger works with Kubernetes-oriented CI/CD solutions. It is Apache 2.0 licensed, free and can be paired with Flux for GitOps pipelines.
Good
- Supports canary, A/B and blue/green strategies.
- Can roll back after detected performance drops.
- Custom metrics and webhooks extend validation.
- Manual approval, pause and resume controls are listed.
- Apache 2.0 licensed and free.
Watch out
- Requires a Kubernetes deployment environment.
- Self-hosted deployment requires operating the service yourself.
Who it suits
Flagger suits teams deploying applications on Kubernetes that want automated traffic shifting, validation and rollback. It is also relevant to teams using Flux for GitOps canary pipelines.
Verdict
Flagger focuses specifically on progressive delivery for Kubernetes, with multiple routing strategies and rollback controls. Its self-hosted model and Kubernetes configuration make it most relevant to teams already working in that environment.
Plans and prices
From Flagger's own pricing page, checked 8 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Flagger | Free | Apache 2.0 licensed · progressive delivery Kubernetes operator |
The facts
Each one read from Flagger's own pages, with the date it was checked.
What it does
- Built-in metrics
- The built-in checks are HTTP request success rate and request duration.checked 8 Oct 2026
- Compatibility
- Flagger is configured with Kubernetes custom resources and is compatible with CI/CD solutions made for Kubernetes.checked 8 Oct 2026
- Configuration
- Flagger is configured using Kubernetes custom resources and works with CI/CD solutions made for Kubernetes.checked 8 Oct 2026
- Deployment strategies
- It supports canary releases, A/B testing, and blue/green deployments.checked 8 Oct 2026
- GitOps
- Flagger can be used in GitOps pipelines with tools such as Flux CD.checked 8 Oct 2026
- History
- Flagger was initially developed in 2018 at Weaveworks by Stefan Prodan and became a CNCF project in 2020.checked 8 Oct 2026
- License
- Flagger is licensed under Apache 2.0.checked 8 Oct 2026
- Manual controls
- The feature matrix lists manual gating to approve, pause, or resume deployments across supported routing integrations.checked 8 Oct 2026
- Metrics
- Release analysis can query Prometheus, InfluxDB, Datadog, New Relic, CloudWatch, Stackdriver, or Graphite.checked 8 Oct 2026
- Metrics integrations
- Metric query integrations listed include Prometheus, Datadog, CloudWatch, New Relic, Graphite, Dynatrace, InfluxDB, and Google Cloud Monitoring.checked 8 Oct 2026
- Notifications
- It can send deployment and canary result notifications to Slack, Microsoft Teams, Discord, and Rocket.checked 8 Oct 2026
- Product
- Flagger is a progressive delivery Kubernetes operator that automates application releases on Kubernetes.checked 8 Oct 2026
- Project history
- Flagger was initially developed at Weaveworks in 2018 by Stefan Prodan and became a CNCF project in 2020.checked 8 Oct 2026
- Project status
- Flagger is a graduated Cloud Native Computing Foundation project and part of the Flux family of GitOps tools.checked 8 Oct 2026
- Purpose
- Flagger automates progressive delivery for applications running on Kubernetes by shifting traffic gradually while measuring metrics and running conformance tests.checked 8 Oct 2026
- Rollback
- If SLO analysis detects a performance drop, Flagger automatically rolls back the release.checked 8 Oct 2026
- Routing
- Traffic routing uses an ingress controller or a service mesh compatible with the Kubernetes Gateway API.checked 8 Oct 2026
- Support
- The project directs users to its documentation, the CNCF community Slack #flagger channel, Flux talks, and GitHub issues for help.checked 8 Oct 2026
- Traffic shifting
- It gradually shifts traffic to a new version while measuring metrics such as HTTP or gRPC request success rate and latency.checked 8 Oct 2026
- Validation
- Built-in metric checks can be extended with custom metrics and webhooks for acceptance tests, load tests, or other validation.checked 8 Oct 2026
The company
- Founded
- 2018checked 23 Sep 2026
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