Flux – GitOps Toolkit components

Flux: Source Controllers

Mon, 01 Jan 0001 00:00:00 +0000

Source controller

The main role of source-controller is to provide a common interface for artifacts acquisition. The source API defines a set of Kubernetes objects that cluster admins and various automated operators can interact with to offload the Git and Helm repositories operations to a dedicated controller.

Features:

Validate source definitions
Authenticate to sources (SSH, user/password, API token)
Validate source authenticity (PGP)
Detect source changes based on update policies (semver)
Fetch resources on-demand and on-a-schedule
Package the fetched resources into a well-known format (tar.gz, yaml)
Make the artifacts addressable by their source identifier (sha, version, ts)
Make the artifacts available in-cluster to interested 3rd parties
Notify interested 3rd parties of source changes and availability (status conditions, events, hooks)

Links:

Source code fluxcd/source-controller
Specification docs

Source watcher

The source-watcher is a GitOps toolkit controller that extends Flux with advanced source composition and decomposition patterns.

The source-watcher controller implements the ArtifactGenerator API, which allows Flux users to:

Compose multiple Flux sources (GitRepository, OCIRepository, Bucket) into a single deployable artifact
Decompose monorepos into multiple independent artifacts with separate deployment lifecycles
Optimize reconciliation by only triggering updates when specific paths change
Structure complex deployments from distributed sources maintained by different teams

Links:

Source code fluxcd/source-watcher
Specification docs

Flux: Kustomize Controller

Mon, 01 Jan 0001 00:00:00 +0000

The kustomize-controller is a Kubernetes operator, specialized in running continuous delivery pipelines for infrastructure and workloads defined with Kubernetes manifests and assembled with Kustomize.

Features:

Reconciles the cluster state from multiple sources (provided by source-controller)
Generates manifests with Kustomize (from plain Kubernetes YAMLs or Kustomize overlays)
Decrypts Kubernetes secrets with Mozilla SOPS and KMS
Validates manifests against Kubernetes API
Impersonates service accounts (multi-tenancy RBAC)
Health assessment of the deployed workloads
Runs pipelines in a specific order (depends-on relationship)
Prunes objects removed from source (garbage collection)
Reports cluster state changes (alerting provided by notification-controller)

Links:

Source code fluxcd/kustomize-controller
Specification docs

Flux: Helm Controller

Mon, 01 Jan 0001 00:00:00 +0000

The Helm Controller is a Kubernetes operator, allowing one to declaratively manage Helm chart releases with Kubernetes manifests.

The desired state of a Helm release is described through a Kubernetes Custom Resource named HelmRelease. Based on the creation, mutation or removal of a HelmRelease resource in the cluster, Helm actions are performed by the controller.

Features:

Watches for HelmRelease objects and generates HelmChart objects
Supports HelmChart artifacts produced from HelmRepository and GitRepository sources
Fetches artifacts produced by source-controller from HelmChart objects
Watches HelmChart objects for revision changes (including semver ranges for charts from HelmRepository sources)
Performs automated Helm actions, including Helm tests, rollbacks and uninstalls
Offers extensive configuration options for automated remediation (rollback, uninstall, retry) on failed Helm install, upgrade or test actions
Runs Helm install/upgrade in a specific order, taking into account the depends-on relationship defined in a set of HelmRelease objects
Prunes Helm releases removed from cluster (garbage collection)
Reports Helm releases statuses (alerting provided by notification-controller)
Built-in Kustomize compatible Helm post renderer, providing support for strategic merge, JSON 6902 and images patches

Links:

Source code fluxcd/helm-controller
Specification docs

Flux: Notification Controller

Mon, 01 Jan 0001 00:00:00 +0000

The Notification Controller is a Kubernetes operator, specialized in handling inbound and outbound events.

The controller handles events coming from external systems (GitHub, GitLab, Bitbucket, Harbor, Jenkins, etc) and notifies the GitOps toolkit controllers about source changes.

The controller handles events emitted by the GitOps toolkit controllers (source, kustomize, helm) and dispatches them to external systems (Slack, Microsoft Teams, Discord, Rocker) based on event severity and involved objects.

Links:

Source code fluxcd/notification-controller
Specification docs

Flux: Image reflector and automation controllers

Mon, 01 Jan 0001 00:00:00 +0000

The image-reflector-controller and image-automation-controller work together to update a Git repository when new container images are available.

The image-reflector-controller scans image repositories and reflects the image metadata in Kubernetes resources.
The image-automation-controller updates YAML files based on the latest images scanned, and commits the changes to a given Git repository.

Links:

Reflector source code fluxcd/image-reflector-controller
Reflector specification docs
Automation source code fluxcd/image-automation-controller
Automation specification docs