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OCI Repositories

The OCIRepository API defines a Source to produce an Artifact for an OCI repository.

Example

The following is an example of an OCIRepository. It creates a tarball (.tar.gz) Artifact with the fetched data from an OCI repository for the resolved digest.

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: podinfo
  namespace: default
spec:
  interval: 5m0s
  url: oci://ghcr.io/stefanprodan/manifests/podinfo
  ref:
    tag: latest

In the above example:

  • An OCIRepository named podinfo is created, indicated by the .metadata.name field.
  • The source-controller checks the OCI repository every five minutes, indicated by the .spec.interval field.
  • It pulls the latest tag of the ghcr.io/stefanprodan/manifests/podinfo repository, indicated by the .spec.ref.tag and .spec.url fields.
  • The resolved SHA256 digest is used as the Artifact revision, reported in-cluster in the .status.artifact.revision field.
  • When the current OCIRepository digest differs from the latest fetched digest, a new Artifact is archived.
  • The new Artifact is reported in the .status.artifact field.

You can run this example by saving the manifest into ocirepository.yaml.

  1. Apply the resource on the cluster:

    kubectl apply -f ocirepository.yaml

  2. Run kubectl get ocirepository to see the OCIRepository:

    NAME      URL                                            AGE   READY   STATUS                                                                        
podinfo   oci://ghcr.io/stefanprodan/manifests/podinfo   5s    True    stored artifact with digest '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de'

  3. Run kubectl describe ocirepository podinfo to see the Artifact and Conditions in the OCIRepository's Status:

    ...
Status:
  Artifact:
    Checksum:          d7e924b4882e55b97627355c7b3d2e711e9b54303afa2f50c25377f4df66a83b
    Last Update Time:  2022-06-14T11:23:36Z
    Path:              ocirepository/default/podinfo/3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de.tar.gz
    Revision:          3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de
    URL:               http://source-controller.flux-system.svc.cluster.local./ocirepository/oci/podinfo/3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de.tar.gz
  Conditions:
    Last Transition Time:  2022-06-14T11:23:36Z
    Message:               stored artifact for digest '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de'
    Observed Generation:   1
    Reason:                Succeeded
    Status:                True
    Type:                  Ready
    Last Transition Time:  2022-06-14T11:23:36Z
    Message:               stored artifact for digest '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de'
    Observed Generation:   1
    Reason:                Succeeded
    Status:                True
    Type:                  ArtifactInStorage
  Observed Generation:     1
  URL:                     http://source-controller.source-system.svc.cluster.local./gitrepository/default/podinfo/latest.tar.gz
Events:
  Type    Reason               Age   From               Message
  ----    ------               ----  ----               -------
  Normal  NewArtifact          62s   source-controller  stored artifact with digest '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de' from 'oci://ghcr.io/stefanprodan/manifests/podinfo'

Writing an OCIRepository spec

As with all other Kubernetes config, an OCIRepository needs apiVersion, kind, and metadata fields. The name of an OCIRepository object must be a valid DNS subdomain name.

An OCIRepository also needs a .spec section.

URL

.spec.url is a required field that specifies the address of the container image repository in the format oci://<host>:<port>/<org-name>/<repo-name>.

Note: that specifying a tag or digest is not acceptable for this field.

Provider

.spec.provider is an optional field that allows specifying an OIDC provider used for authentication purposes.

Supported options are:

  • generic
  • aws
  • azure
  • gcp

The generic provider can be used for public repositories or when static credentials are used for authentication, either with spec.secretRef or spec.serviceAccountName. If you do not specify .spec.provider, it defaults to generic.

The aws provider can be used when the source-controller service account is associated with an AWS IAM Role using IRSA that grants read-only access to ECR.

The azure provider can be used when the source-controller pods are associated with an Azure AAD Pod Identity that grants read-only access to ACR.

The gcp provider can be used when the source-controller service account is associated with a GCP IAM Role using Workload Identity that grants read-only access to Artifact Registry.

Secret reference

.spec.secretRef.name is an optional field to specify a name reference to a Secret in the same namespace as the OCIRepository, containing authentication credentials for the OCI repository.

This secret is expected to be in the same format as imagePullSecrets. The usual way to create such a secret is with:

kubectl create secret docker-registry ...

Service Account reference

.spec.serviceAccountName is an optional field to specify a name reference to a Service Account in the same namespace as the OCIRepository. The controller will fetch the image pull secrets attached to the service account and use them for authentication.

Note: that for a publicly accessible image repository, you don't need to provide a secretRef nor serviceAccountName.

TLS Certificates

.spec.certSecretRef field names a secret with TLS certificate data. This is for two separate purposes:

  • to provide a client certificate and private key, if you use a certificate to authenticate with the container registry; and,
  • to provide a CA certificate, if the registry uses a self-signed certificate.

These will often go together, if you are hosting a container registry yourself. All the files in the secret are expected to be PEM-encoded. This is an ASCII format for certificates and keys; openssl and such tools will typically give you an option of PEM output.

Assuming you have obtained a certificate file and private key and put them in the files client.crt and client.key respectively, you can create a secret with kubectl like this:

kubectl create secret generic tls-certs \
  --from-file=certFile=client.crt \
  --from-file=keyFile=client.key

You could also prepare a secret and encrypt it; the important bit is that the data keys in the secret are certFile and keyFile.

If you have a CA certificate for the client to use, the data key for that is caFile. Adapting the previous example, if you have the certificate in the file ca.crt, and the client certificate and key as before, the whole command would be:

kubectl create secret generic tls-certs \
  --from-file=certFile=client.crt \
  --from-file=keyFile=client.key \
  --from-file=caFile=ca.crt

Interval

.spec.interval is a required field that specifies the interval at which the OCI repository must be fetched.

After successfully reconciling the object, the source-controller requeues it for inspection after the specified interval. The value must be in a Go recognized duration string format, e.g. 10m0s to reconcile the object every 10 minutes.

If the .metadata.generation of a resource changes (due to e.g. a change to the spec), this is handled instantly outside the interval window.

Timeout

.spec.timeout is an optional field to specify a timeout for OCI operations like pulling. The value must be in a Go recognized duration string format, e.g. 1m30s for a timeout of one minute and thirty seconds. The default value is 60s.

Reference

.spec.ref is an optional field to specify the OCI reference to resolve and watch for changes. References are specified in one or more subfields (.tag, .semver, .digest), with latter listed fields taking precedence over earlier ones. If not specified, it defaults to the latest tag.

Tag example

To pull a specific tag, use .spec.ref.tag:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  ref:
    tag: "<tag-name>"

SemVer example

To pull a tag based on a SemVer range, use .spec.ref.semver:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  ref:
    # SemVer range reference: https://github.com/Masterminds/semver#checking-version-constraints
    semver: "<semver-range>"

This field takes precedence over .tag.

Digest example

To pull a specific digest, use .spec.ref.digest:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  ref:
    digest: "sha256:<SHA-value>"

This field takes precedence over all other fields.

Ignore

.spec.ignore is an optional field to specify rules in the .gitignore pattern format. Paths matching the defined rules are excluded while archiving.

When specified, .spec.ignore overrides the default exclusion list, and may overrule the .sourceignore file exclusions. See excluding files for more information.

Suspend

.spec.suspend is an optional field to suspend the reconciliation of a OCIRepository. When set to true, the controller will stop reconciling the OCIRepository, and changes to the resource or in the OCI repository will not result in a new Artifact. When the field is set to false or removed, it will resume.

Working with OCIRepositories

Excluding files

By default, files which match the default exclusion rules are excluded while archiving the OCI repository contents as an Artifact. It is possible to overwrite and/or overrule the default exclusions using the .spec.ignore field.

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  ignore: |
    # exclude all
    /*
    # include deploy dir
    !/deploy
    # exclude file extensions from deploy dir
    /deploy/**/*.md
    /deploy/**/*.txt

Triggering a reconcile

To manually tell the source-controller to reconcile a OCIRepository outside the specified interval window, an OCIRepository can be annotated with reconcile.fluxcd.io/requestedAt: <arbitrary value>. Annotating the resource queues the OCIRepository for reconciliation if the <arbitrary-value> differs from the last value the controller acted on, as reported in .status.lastHandledReconcileAt.

Using kubectl:

kubectl annotate --field-manager=flux-client-side-apply --overwrite ocirepository/<repository-name> reconcile.fluxcd.io/requestedAt="$(date +%s)"

Using flux:

flux reconcile source oci <repository-name>

Waiting for Ready

When a change is applied, it is possible to wait for the OCIRepository to reach a ready state using kubectl:

kubectl wait gitrepository/<repository-name> --for=condition=ready --timeout=1m

Suspending and resuming

When you find yourself in a situation where you temporarily want to pause the reconciliation of an OCIRepository, you can suspend it using the .spec.suspend field.

Suspend an OCIRepository

In your YAML declaration:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  suspend: true

Using kubectl:

kubectl patch ocirepository <repository-name> --field-manager=flux-client-side-apply -p '{\"spec\": {\"suspend\" : true }}'

Using flux:

flux suspend source oci <repository-name>

Note: When an OCIRepository has an Artifact and it is suspended, and this Artifact later disappears from the storage due to e.g. the source-controller Pod being evicted from a Node, this will not be reflected in the OCIRepository's Status until it is resumed.

Resume an OCIRepository

In your YAML declaration, comment out (or remove) the field:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
spec:
  # suspend: true

Note: Setting the field value to false has the same effect as removing it, but does not allow for "hot patching" using e.g. kubectl while practicing GitOps; as the manually applied patch would be overwritten by the declared state in Git.

Using kubectl:

kubectl patch ocirepository <repository-name> --field-manager=flux-client-side-apply -p '{\"spec\" : {\"suspend\" : false }}'

Using flux:

flux resume source oci <repository-name>

Debugging an OCIRepository

There are several ways to gather information about a OCIRepository for debugging purposes.

Describe the OCIRepository

Describing an OCIRepository using kubectl describe ocirepository <repository-name> displays the latest recorded information for the resource in the Status and Events sections:

...
Status:
...
  Conditions:
    Last Transition Time:  2022-02-14T09:40:27Z
    Message:               reconciling new object generation (2)
    Observed Generation:   2
    Reason:                NewGeneration
    Status:                True
    Type:                  Reconciling
    Last Transition Time:  2022-02-14T09:40:27Z
    Message:               failed to pull artifact from 'oci://ghcr.io/stefanprodan/manifests/podinfo': couldn't find tag "0.0.1"
    Observed Generation:   2
    Reason:                OCIOperationFailed
    Status:                False
    Type:                  Ready
    Last Transition Time:  2022-02-14T09:40:27Z
    Message:               failed to pull artifact from 'oci://ghcr.io/stefanprodan/manifests/podinfo': couldn't find tag "0.0.1"
    Observed Generation:   2
    Reason:                OCIOperationFailed
    Status:                True
    Type:                  FetchFailed
  Observed Generation:     1
  URL:                     http://source-controller.source-system.svc.cluster.local./ocirepository/default/podinfo/latest.tar.gz
Events:
  Type     Reason                      Age                  From               Message
  ----     ------                      ----                 ----               -------
  Warning  OCIOperationFailed          2s (x9 over 4s)      source-controller  failed to pull artifact from 'oci://ghcr.io/stefanprodan/manifests/podinfo': couldn't find tag "0.0.1"

Trace emitted Events

To view events for specific OCIRepository(s), kubectl get events can be used in combination with --field-sector to list the Events for specific objects. For example, running

kubectl get events --field-selector involvedObject.kind=OCIRepository,involvedObject.name=<repository-name>

lists

LAST SEEN   TYPE     REASON                OBJECT                               MESSAGE
2m14s       Normal   NewArtifact           ocirepository/<repository-name>      stored artifact for digest '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de'
36s         Normal   ArtifactUpToDate      ocirepository/<repository-name>      artifact up-to-date with remote digest: '3b6cdcc7adcc9a84d3214ee1c029543789d90b5ae69debe9efa3f66e982875de'
94s         Warning  OCIOperationFailed    ocirepository/<repository-name>      failed to pull artifact from 'oci://ghcr.io/stefanprodan/manifests/podinfo': couldn't find tag "0.0.1"

Besides being reported in Events, the reconciliation errors are also logged by the controller. The Flux CLI offer commands for filtering the logs for a specific OCIRepository, e.g. flux logs --level=error --kind=OCIRepository --name=<repository-name>.

OCIRepository Status

Artifact

The OCIRepository reports the latest synchronized state from the OCI repository as an Artifact object in the .status.artifact of the resource.

The .status.artifact.revision holds the SHA256 digest of the upstream OCI artifact.

The .status.artifact.metadata holds the upstream OCI artifact metadata such as the OpenContainers standard annotations. If the OCI artifact was created with flux push artifact, then the metadata will contain the following annotations:

  • org.opencontainers.image.created the date and time on which the artifact was built
  • org.opencontainers.image.source the URL of the Git repository containing the source files
  • org.opencontainers.image.revision the Git branch and commit SHA1 of the source files

The Artifact file is a gzip compressed TAR archive (<commit sha>.tar.gz), and can be retrieved in-cluster from the .status.artifact.url HTTP address.

Artifact example

apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: OCIRepository
metadata:
  name: <repository-name>
status:
  artifact:
    checksum: 9f3bc0f341d4ecf2bab460cc59320a2a9ea292f01d7b96e32740a9abfd341088
    lastUpdateTime: "2022-08-08T09:35:45Z"
    metadata:
      org.opencontainers.image.created: "2022-08-08T12:31:41+03:00"
      org.opencontainers.image.revision: 6.1.8/b3b00fe35424a45d373bf4c7214178bc36fd7872
      org.opencontainers.image.source: https://github.com/stefanprodan/podinfo.git
    path: ocirepository/<namespace>/<repository-name>/<digest>.tar.gz
    revision: <digest>
    url: http://source-controller.<namespace>.svc.cluster.local./ocirepository/<namespace>/<repository-name>/<digest>.tar.gz

Default exclusions

The following files and extensions are excluded from the Artifact by default:

  • Git files (.git/, .gitignore, .gitmodules, .gitattributes)
  • File extensions (.jpg, .jpeg, .gif, .png, .wmv, .flv, .tar.gz, .zip)
  • CI configs (.github/, .circleci/, .travis.yml, .gitlab-ci.yml, appveyor.yml, .drone.yml, cloudbuild.yaml, codeship-services.yml, codeship-steps.yml)
  • CLI configs (.goreleaser.yml, .sops.yaml)
  • Flux v1 config (.flux.yaml)

To define your own exclusion rules, see excluding files.

Conditions

OCIRepository has various states during its lifecycle, reflected as Kubernetes Conditions. It can be reconciling while fetching the remote state, it can be ready, or it can fail during reconciliation.

The OCIRepository API is compatible with the kstatus specification, and reports Reconciling and Stalled conditions where applicable to provide better (timeout) support to solutions polling the OCIRepository to become Ready.

Reconciling OCIRepository

The source-controller marks an OCIRepository as reconciling when one of the following is true:

  • There is no current Artifact for the OCIRepository, or the reported Artifact is determined to have disappeared from the storage.
  • The generation of the OCIRepository is newer than the Observed Generation.
  • The newly resolved Artifact digest differs from the current Artifact.

When the OCIRepository is "reconciling", the Ready Condition status becomes False, and the controller adds a Condition with the following attributes to the OCIRepository's .status.conditions:

  • type: Reconciling
  • status: "True"
  • reason: NewGeneration | reason: NoArtifact | reason: NewRevision

If the reconciling state is due to a new revision, an additional Condition is added with the following attributes:

  • type: ArtifactOutdated
  • status: "True"
  • reason: NewRevision

Both Conditions have a "negative polarity", and are only present on the OCIRepository while their status value is "True".

Ready OCIRepository

The source-controller marks an OCIRepository as ready when it has the following characteristics:

  • The OCIRepository reports an Artifact.
  • The reported Artifact exists in the controller's Artifact storage.
  • The controller was able to communicate with the remote OCI repository using the current spec.
  • The digest of the reported Artifact is up-to-date with the latest resolved digest of the remote OCI repository.

When the OCIRepository is "ready", the controller sets a Condition with the following attributes in the OCIRepository's .status.conditions:

  • type: Ready
  • status: "True"
  • reason: Succeeded

This Ready Condition will retain a status value of "True" until the OCIRepository is marked as reconciling, or e.g. a transient error occurs due to a temporary network issue.

When the OCIRepository Artifact is archived in the controller's Artifact storage, the controller sets a Condition with the following attributes in the OCIRepository's .status.conditions:

  • type: ArtifactInStorage
  • status: "True"
  • reason: Succeeded

This ArtifactInStorage Condition will retain a status value of "True" until the Artifact in the storage no longer exists.

Failed OCIRepository

The source-controller may get stuck trying to produce an Artifact for a OCIRepository without completing. This can occur due to some of the following factors:

  • The remote OCI repository URL is temporarily unavailable.
  • The OCI repository does not exist.
  • The Secret reference contains a reference to a non-existing Secret.
  • The credentials in the referenced Secret are invalid.
  • The OCIRepository spec contains a generic misconfiguration.
  • A storage related failure when storing the artifact.

When this happens, the controller sets the Ready Condition status to False, and adds a Condition with the following attributes to the OCIRepository's .status.conditions:

  • type: FetchFailed | type: IncludeUnavailable | type: StorageOperationFailed
  • status: "True"
  • reason: AuthenticationFailed | reason: OCIArtifactPullFailed | reason: OCIArtifactLayerOperationFailed

This condition has a "negative polarity", and is only present on the OCIRepository while the status value is "True". There may be more arbitrary values for the reason field to provide accurate reason for a condition.

While the OCIRepository has one or more of these Conditions, the controller will continue to attempt to produce an Artifact for the resource with an exponential backoff, until it succeeds and the OCIRepository is marked as ready.

Note that a OCIRepository can be reconciling while failing at the same time, for example due to a newly introduced configuration issue in the OCIRepository spec.

Content Configuration Checksum

The source-controller calculates the SHA256 checksum of the various configurations of the OCIRepository that indicate a change in source and records it in .status.contentConfigChecksum. This field is used to determine if the source artifact needs to be rebuilt.

Observed Generation

The source-controller reports an observed generation in the OCIRepository's .status.observedGeneration. The observed generation is the latest .metadata.generation which resulted in either a ready state, or stalled due to error it can not recover from without human intervention.

Last Handled Reconcile At

The source-controller reports the last reconcile.fluxcd.io/requestedAt annotation value it acted on in the .status.lastHandledReconcileAt field.

For practical information about this field, see triggering a reconcile.