mirror of https://github.com/fluxcd/flux2.git
Move the v1 vs v2 FAQ to the migration section
Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>pull/1033/head
Stefan Prodan
4 years ago
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## Flux v1 vs v2 questions
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### What does Flux v2 mean for Flux?
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Flux v1 is a monolithic do-it-all operator; Flux v2 separates the functionalities into specialized controllers, collectively called the GitOps Toolkit.
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You can install and operate Flux v2 simply using the `flux` command. You can easily pick and choose the functionality you need and extend it to serve your own purposes.
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The timeline we are looking at right now is:
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1. Put Flux v1 into maintenance mode (no new features being added; bugfixes and CVEs patched only).
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1. Continue work on the [Flux v2 roadmap](https://toolkit.fluxcd.io/roadmap/).
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1. We will provide transition guides for specific user groups, e.g. users of Flux v1 in read-only mode, or of Helm Operator v1, etc. once the functionality is integrated into Flux v2 and it's deemed "ready".
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1. Once the use-cases of Flux v1 are covered, we will continue supporting Flux v1 for 6 months. This will be the transition period before it's considered unsupported.
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### Why did you rewrite Flux?
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Flux v2 implements its functionality in individual controllers, which allowed us to address long-standing feature requests much more easily.
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By basing these controllers on modern Kubernetes tooling (`controller-runtime` libraries), they can be dynamically configured with Kubernetes custom resources either by cluster admins or by other automated tools -- and you get greatly increased observability.
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This gave us the opportunity to build Flux v2 with the top Flux v1 feature requests in mind:
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- Supporting multiple source Git repositories
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- Operational insight through health checks, events and alerts
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- Multi-tenancy capabilities, like applying each source repository with its own set of permissions
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On top of that, testing the individual components and understanding the codebase becomes a lot easier.
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### What are significant new differences between Flux v1 and Flux v2?
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#### Reconciliation
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Flux v1 | Flux v2
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---------------------------------- | ----------------------------------
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Limited to a single Git repository | Multiple Git repositories
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Declarative config via arguments in the Flux deployment | `GitRepository` custom resource, which produces an artifact which can be reconciled by other controllers
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Follow `HEAD` of Git branches | Supports Git branches, pinning on commits and tags, follow SemVer tag ranges
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Suspending of reconciliation by downscaling Flux deployment | Reconciliation can be paused per resource by suspending the `GitRepository`
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Credentials config via Arguments and/or Secret volume mounts in the Flux pod | Credentials config per `GitRepository` resource: SSH private key, HTTP/S username/password/token, OpenPGP public keys
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#### `kustomize` support
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Flux v1 | Flux v2
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---------------------------------- | ----------------------------------
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Declarative config through `.flux.yaml` files in the Git repository | Declarative config through a `Kustomization` custom resource, consuming the artifact from the GitRepository
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Manifests are generated via shell exec and then reconciled by `fluxd` | Generation, server-side validation, and reconciliation is handled by a specialised `kustomize-controller`
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Reconciliation using the service account of the Flux deployment | Support for service account impersonation
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Garbage collection needs cluster role binding for Flux to query the Kubernetes discovery API | Garbage collection needs no cluster role binding or access to Kubernetes discovery API
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Support for custom commands and generators executed by fluxd in a POSIX shell | No support for custom commands
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#### Helm integration
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Flux v1 | Flux v2
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---------------------------------- | ----------------------------------
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Declarative config in a single Helm custom resource | Declarative config through `HelmRepository`, `GitRepository`, `Bucket`, `HelmChart` and `HelmRelease` custom resources
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Chart synchronisation embedded in the operator | Extensive release configuration options, and a reconciliation interval per source
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Support for fixed SemVer versions from Helm repositories | Support for SemVer ranges for `HelmChart` resources
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Git repository synchronisation on a global interval | Planned support for charts from GitRepository sources
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Limited observability via the status object of the HelmRelease resource | Better observability via the HelmRelease status object, Kubernetes events, and notifications
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Resource heavy, relatively slow | Better performance
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Chart changes from Git sources are determined from Git metadata | Chart changes must be accompanied by a version bump in `Chart.yaml` to produce a new artifact
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#### Notifications, webhooks, observability
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Flux v1 | Flux v2
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---------------------------------- | ----------------------------------
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Emits "custom Flux events" to a webhook endpoint | Emits Kubernetes events for included custom resources
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RPC endpoint can be configured to a 3rd party solution like FluxCloud to be forwarded as notifications to e.g. Slack | Flux v2 components can be configured to POST the events to a `notification-controller` endpoint. Selective forwarding of POSTed events as notifications using `Provider` and `Alert` custom resources.
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Webhook receiver is a side-project | Webhook receiver, handling a wide range of platforms, is included
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Unstructured logging | Structured logging for all components
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Custom Prometheus metrics | Generic / common `controller-runtime` Prometheus metrics
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### Are there any breaking changes?
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- In Flux v1 Kustomize support was implemented through `.flux.yaml` files in the Git repository. As indicated in the comparison table above, while this approach worked, we found it to be error-prone and hard to debug. The new [Kustomization CR](https://github.com/fluxcd/kustomize-controller/blob/master/docs/spec/v1alpha1/kustomization.md) should make troubleshooting much easier. Unfortunately we needed to drop the support for custom commands as running arbitrary shell scripts in-cluster poses serious security concerns.
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- Helm users: we redesigned the `HelmRelease` API and the automation will work quite differently, so upgrading to `HelmRelease` v2 will require a little work from you, but you will gain more flexibility, better observability and performance.
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### Is the GitOps Toolkit related to the GitOps Engine?
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In an announcement in August 2019, the expectation was set that the Flux project would integrate the GitOps Engine, then being factored out of ArgoCD. Since the result would be backward-incompatible, it would require a major version bump: Flux v2.
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After experimentation and considerable thought, we (the maintainers) have found a path to Flux v2 that we think better serves our vision of GitOps: the GitOps Toolkit. In consequence, we do not now plan to integrate GitOps Engine into Flux.
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### How can I get involved?
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There are a variety of ways and we look forward to having you on board building the future of GitOps together:
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- [Discuss the direction](https://github.com/fluxcd/flux2/discussions) of Flux v2 with us
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- Join us in #flux-dev on the [CNCF Slack](https://slack.cncf.io)
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- Check out our [contributor docs](https://toolkit.fluxcd.io/contributing/)
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- Take a look at the [roadmap for Flux v2](https://toolkit.fluxcd.io/roadmap/)
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