Frequently asked questions
General questions
Does Flux have a UI / GUI?
The Flux project does not provide a UI of its own, but there are a variety of UIs for Flux in the Flux Ecosystem.
Capacitor
VS Code GitOps Tools
Weave GitOps
Where can I find information about Flux release cadence and supported versions?
Flux is at least released at the same rate as Kubernetes, following their cadence of three minor releases per year.
For Flux the CLI and its controllers, we support the last three minor releases. Critical bug fixes, such as security fixes, may be back-ported to those three minor versions as patch releases, depending on severity and feasibility.
For more details please see the Flux release documentation.
Kustomize questions
Are there two Kustomization types?
Yes, the kustomization.kustomize.toolkit.fluxcd.io
is a Kubernetes
custom resource
while kustomization.kustomize.config.k8s.io
is the type used to configure a
Kustomize overlay.
The kustomization.kustomize.toolkit.fluxcd.io
object refers to a kustomization.yaml
file path inside a Git repository or Bucket source.
How do I use them together?
Assuming an app repository with ./deploy/prod/kustomization.yaml
:
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: default
resources:
- deployment.yaml
- service.yaml
- ingress.yaml
Define a source of type gitrepository.source.toolkit.fluxcd.io
that pulls changes from the app repository every 5 minutes inside the cluster:
apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
name: my-app
namespace: default
spec:
interval: 5m
url: https://github.com/my-org/my-app
ref:
branch: main
Then define a kustomization.kustomize.toolkit.fluxcd.io
that uses the kustomization.yaml
from ./deploy/prod
to determine which resources to create, update or delete:
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
name: my-app
namespace: default
spec:
interval: 15m
path: "./deploy/prod"
prune: true
sourceRef:
kind: GitRepository
name: my-app
What is a Kustomization reconciliation?
In the above example, we pull changes from Git every 5 minutes,
and a new commit will trigger a reconciliation of
all the Kustomization
objects using that source.
Depending on your configuration, a reconciliation can mean:
- generating a kustomization.yaml file in the specified path
- building the kustomize overlay
- decrypting secrets
- validating the manifests with client or server-side dry-run
- applying changes on the cluster
- health checking of deployed workloads
- garbage collection of resources removed from Git
- issuing events about the reconciliation result
- recoding metrics about the reconciliation process
The 15 minutes reconciliation interval, is the interval at which you want to undo manual changes
.e.g. kubectl set image deployment/my-app
by reapplying the latest commit on the cluster.
Note that a reconciliation will override all fields of a Kubernetes object, that diverge from Git.
For example, you’ll have to omit the spec.replicas
field from your Deployments
YAMLs if you
are using a HorizontalPodAutoscaler
that changes the replicas in-cluster.
Can I use repositories with plain YAMLs?
Yes, you can specify the path where the Kubernetes manifests are,
and kustomize-controller will generate a kustomization.yaml
if one doesn’t exist.
Assuming an app repository with the following structure:
├── deploy
│  └── prod
│  ├── .yamllint.yaml
│  ├── deployment.yaml
│  ├── service.yaml
│  └── ingress.yaml
└── src
Create a GitRepository
definition and exclude all the files that are not Kubernetes manifests:
apiVersion: source.toolkit.fluxcd.io/v1
kind: GitRepository
metadata:
name: my-app
namespace: default
spec:
interval: 5m
url: https://github.com/my-org/my-app
ref:
branch: main
ignore: |
# exclude all
/*
# include deploy dir
!/deploy
# exclude non-Kubernetes YAMLs
/deploy/**/.yamllint.yaml
Then create a Kustomization
definition to reconcile the ./deploy/prod
dir:
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
name: my-app
namespace: default
spec:
interval: 15m
path: "./deploy/prod"
prune: true
sourceRef:
kind: GitRepository
name: my-app
With the above configuration, source-controller will pull the Kubernetes manifests
from the app repository and kustomize-controller will generate a
kustomization.yaml
including all the resources found with ./deploy/prod/**/*.yaml
.
The kustomize-controller creates kustomization.yaml
files similar to:
cd ./deploy/prod && kustomize create --autodetect --recursive
How can I safely move resources from one dir to another?
To move manifests from a directory synced by a Flux Kustomization to another dir synced by a different Kustomization, first you need to disable garbage collection then move the files.
Assuming you have two Flux Kustomization named app1
and app2
, and you want to move a
deployment manifests named deploy.yaml
from app1
to app2
:
- Disable garbage collection by setting
prune: false
in theapp1
Flux Kustomization. Commit, push and reconcile the changes e.g.flux reconcile ks flux-system --with-source
. - Verify that pruning is disabled in-cluster with
flux export ks app1
. - Move the
deploy.yaml
manifest to theapp2
dir, then commit, push and reconcile e.g.flux reconcile ks app2 --with-source
. - Verify that the deployment is now managed by the
app2
Kustomization withflux tree ks apps2
. - Reconcile the
app1
Kustomization and verify that the deployment is no longer managed by itflux reconcile ks app1 && flux tree ks app1
. - Finally, enable garbage collection by setting
prune: true
inapp1
Kustomization, then commit and push the changes upstream.
Another option is to disable the garbage collection of the objects using an annotation:
- Disable garbage collection in the
deploy.yaml
by adding thekustomize.toolkit.fluxcd.io/prune: disabled
annotation. - Commit, push and reconcile the changes e.g.
flux reconcile ks flux-system --with-source
. - Verify that the annotation has been applied
kubectl get deploy/app1 -o yaml
. - Move the
deploy.yaml
manifest to theapp2
dir, then commit, push and reconcile e.g.flux reconcile ks app2 --with-source
. - Reconcile the
app1
Kustomization and verify that the deployment is no longer managed by itflux reconcile ks app1 && flux tree ks app1
. - Finally, enable garbage collection by setting
kustomize.toolkit.fluxcd.io/prune: enabled
, then commit and push the changes upstream.
How can I safely rename a Flux Kustomization?
If a Flux Kustomization has spec.prune
set to true
and you rename the object, then all reconciled
workloads will be deleted and recreated.
To safely rename a Flux Kustomization, first set spec.prune
to false
and sync the change on the cluster.
To make sure that the change has been acknowledged by Flux, run flux export kustomization <name>
and check that pruning is disabled. Finally, rename the Kustomization and re-enabled pruning. Flux will
delete the old Kustomization and transfer ownership of the reconciled resources to the new Kustomization.
You can run flux tree kustomization <new-name>
to see which resources are managed by Flux.
Why are kubectl edits rolled back by Flux?
If you use kubectl to edit an object managed by Flux, all changes will be undone when kustomize-controller reconciles a Flux Kustomization containing that object.
In order for Flux to preserve fields added with kubectl, for example a label or annotation,
you have to specify a field manager named flux-client-side-apply
.
For example, to manually add a label to a resource, do:
kubectl --field-manager=flux-client-side-apply label ...
Note that fields specified in Git will always be overridden, the above procedure works only for adding new fields that don’t overlap with the desired state.
Rollout restarts add a “restartedAt” annotation, which flux will remove, re-deploying the pods.
To complete a rollout restart successfully, use the flux-client-side-apply
field manager e.g.:
kubectl --field-manager=flux-client-side-apply rollout restart ...
Should I be using Kustomize remote bases?
For security and performance reasons, it is advised to disallow the usage of
remote bases
in Kustomize overlays. To enforce this setting, platform admins can set the --no-remote-bases=true
flag for kustomize-controller.
Note: This flag prevents the usage of remote bases only, i.e. a Git repository or a sub directory. It does not affect the usage of remote targets pointing to a single file.
When using remote bases, the manifests are fetched over HTTPS from their remote source on every reconciliation e.g.:
# infra/kyverno/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
- https://github.com/stefanprodan/podinfo/deploy/overlays/dev?ref=master
To take advantage of Flux’s verification and caching features,
you can replace the kustomization.yaml
with a Flux source definition:
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
name: kyverno
namespace: flux-system
spec:
interval: 60m
url: oci://ghcr.io/kyverno/manifests/kyverno
ref: # pull the latest patch release evey hour
semver: 1.8.x
verify: # enable Cosign keyless verification
provider: cosign
Then to reconcile the manifests on a cluster, you’ll use the ones from the verified source:
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
name: kyverno
namespace: flux-system
spec:
interval: 360m
prune: true
wait: true
timeout: 5m
sourceRef:
kind: OCIRepository
name: kyverno
path: ./
kubeConfig:
secretRef:
name: staging-cluster
Should I be using Kustomize Helm chart plugin?
Due to security and performance reasons, Flux does not allow the execution of Kustomize plugins which shell-out to arbitrary binaries insides the kustomize-controller container.
Instead of using Kustomize to deploy charts, e.g.:
# infra/kyverno/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: kyverno
resources:
- kyverno-namespace.yaml
helmCharts:
- name: kyverno
valuesInline:
networkPolicy:
enabled: true
releaseName: kyverno
version: 2.6.0
repo: https://kyverno.github.io/kyverno/
You can take advantage of Flux’s OCI and native Helm features,
by replacing the kustomization.yaml
with a Flux Helm definition:
apiVersion: source.toolkit.fluxcd.io/v1
kind: HelmRepository
metadata:
name: kyverno
namespace: flux-system
spec:
interval: 6h
url: oci://ghcr.io/kyverno/charts
type: oci
---
apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
name: kyverno
namespace: flux-system
spec:
interval: 6h
releaseName: kyverno
targetNamespace: kyverno
install:
createNamespace: true
chart:
spec:
chart: kyverno
version: 2.6.0
interval: 6h
sourceRef:
kind: HelmRepository
name: kyverno
values:
networkPolicy:
enabled: true
What is the behavior of Kustomize used by Flux?
We referred to the Kustomize v5 CLI flags here,
so that you can replicate the same behavior using kustomize build
:
---enable-alpha-plugins
is disabled by default, so it uses only the built-in plugins.--load-restrictor
is set toLoadRestrictionsNone
, so it allows loading files outside the dir containingkustomization.yaml
.
To replicate the build and apply dry run locally:
kustomize build --load-restrictor=LoadRestrictionsNone . \
| kubectl apply --server-side --dry-run=server -f-
kustomization.yaml validation
To validate changes before committing and/or merging, a validation utility script is available, it runskustomize
locally or in CI with the same set of flags as
the controller and validates the output using kubeconform
.How to patch CoreDNS and other pre-installed addons?
To patch a pre-installed addon like CoreDNS with customized content,
add a shell manifest with only the changed values and kustomize.toolkit.fluxcd.io/ssa: merge
annotation into your Git repository.
Example CoreDNS with custom replicas, the spec.containers[]
empty list is needed
for the patch to work and will not override the existing containers:
---
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
k8s-app: kube-dns
annotations:
kustomize.toolkit.fluxcd.io/prune: disabled
kustomize.toolkit.fluxcd.io/ssa: merge
name: coredns
namespace: kube-system
spec:
replicas: 5
selector:
matchLabels:
eks.amazonaws.com/component: coredns
k8s-app: kube-dns
template:
metadata:
labels:
eks.amazonaws.com/component: coredns
k8s-app: kube-dns
spec:
containers: []
Note that only non-managed fields should be modified else there will be a conflict with
the manager
of the fields (e.g. eks
). For example, while you will be able to modify
affinity/antiaffinity fields, the manager
(e.g. eks
) will revert those changes and
that might not be immediately visible to you
(with EKS that would be an interval of once every 30 minutes).
The deployment will go into a rolling upgrade and Flux will revert it back to the patched version.
Helm questions
Can I use Flux HelmReleases without GitOps?
Yes, you can install the Flux components directly on a cluster
and manage Helm releases with kubectl
.
Install the controllers needed for Helm operations with flux
:
flux install \
--namespace=flux-system \
--network-policy=false \
--components=source-controller,helm-controller
Create a Helm release with kubectl
:
cat << EOF | kubectl apply -f -
---
apiVersion: source.toolkit.fluxcd.io/v1
kind: HelmRepository
metadata:
name: bitnami
namespace: flux-system
spec:
interval: 30m
url: https://charts.bitnami.com/bitnami
---
apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
name: metrics-server
namespace: kube-system
spec:
interval: 60m
releaseName: metrics-server
chart:
spec:
chart: metrics-server
version: "^5.x"
sourceRef:
kind: HelmRepository
name: bitnami
namespace: flux-system
values:
apiService:
create: true
EOF
Based on the above definition, Flux will upgrade the release automatically when Bitnami publishes a new version of the metrics-server chart.
How do I set local overrides to a Helm chart?
Lets assume we have a common HelmRelease
definition we use as a base and we
we need to further customize it e.g per cluster, tenant, environment and so on:
apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
name: podinfo
namespace: podinfo
spec:
releaseName: podinfo
chart:
spec:
chart: podinfo
sourceRef:
kind: HelmRepository
name: podinfo
interval: 50m
install:
remediation:
retries: 3
and we want to override the chart version per cluster for example to gradually roll out a new version. We have couple options:
Using Kustomize patches
---
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
name: apps
namespace: flux-system
spec:
interval: 30m
retryInterval: 2m
sourceRef:
kind: GitRepository
name: flux-system
path: ./apps/production
prune: true
wait: true
timeout: 5m0s
patches:
- patch: |-
- op: replace
path: /spec/chart/spec/version
value: 4.0.1
target:
kind: HelmRelease
name: podinfo
namespace: podinfo
Using Kustomize variable substitution
apiVersion: helm.toolkit.fluxcd.io/v2
kind: HelmRelease
metadata:
name: podinfo
namespace: podinfo
spec:
releaseName: podinfo
chart:
spec:
chart: podinfo
version: ${PODINFO_CHART_VERSION:=6.2.0}
sourceRef:
kind: HelmRepository
name: podinfo
interval: 50m
install:
remediation:
retries: 3
To enable the replacement of the PODINFO_CHART_VERSION
variable with a different
version than the 6.2.0
default, specify postBuild
in the Kustomization
:
apiVersion: kustomize.toolkit.fluxcd.io/v1
kind: Kustomization
metadata:
name: apps
namespace: flux-system
spec:
interval: 30m
retryInterval: 2m
sourceRef:
kind: GitRepository
name: flux-system
path: ./apps/production
prune: true
wait: true
timeout: 5m0s
postBuild:
substitute:
PODINFO_CHART_VERSION: 6.3.0
Flux v1 vs v2 questions
What are the differences between v1 and v2?
Flux v1 is a monolithic do-it-all operator; it has reached its EOL and has been archived. Flux v2 separates the functionalities into specialized controllers, collectively called the GitOps Toolkit.
You can find a detailed comparison of Flux v1 and v2 features in the migration FAQ.
How can I migrate from v1 to v2?
The Flux community has created guides and example repositories to help you migrate to Flux v2:
- Migrate from Flux v1
- Migrate from
.flux.yaml
and kustomize - Migrate from Flux v1 automated container image updates
- How to manage multi-tenant clusters with Flux v2
- Migrate from Helm Operator to Flux v2
- How to structure your HelmReleases