Integrate Keptn with your Applications
Keptn works on top of the default scheduler for the cluster. This allows it to:
- Track all activities of all workloads on the cluster, no matter what tool is used for the deployment
- Inject pre/post-deployment checks into all workloads.
Keptn monitors resources that have been applied into the Kubernetes cluster and reacts if it finds a workload with special annotations/labels. Keptn uses metadata that is added to the Kubernetes workloads to identify the workloads of interest.
To integrate Keptn with your workloads:
- You must first install and enable Keptn.
Note: Annotations are not required if you are only using the
metrics-operatorcomponent of Keptn to observe Keptn metrics.
Keptn automatically discovers
based on the annotations or labels.
This enables the Keptn observability features
(based on OpenTelemetry) for existing applications,
without additional Keptn configuration.
Keptn monitors your
resources in the namespaces where Keptn is enabled.
If Keptn finds any of these resources and the resource has either
keptn.sh or the
it creates appropriate
resources for the version it detects.
The basic keptn.sh keys that can be used for annotations or labels are:
Alternatively, you can use Kubernetes keys for annotations or labels. These are part of the Kubernetes Recommended Labels:
These keys are defined as:
app.kubernetes.io/name: Determines the name of the generated KeptnWorkload resource.
app.kubernetes.io/version: Determines the version of the
KeptnWorkloadthat represents the Workload. If the Workload has no
versionannotation/labels and the pod has only one container, Keptn takes the image tag as version (unless it is "latest").
app.kubernetes.io/part-of: Determines the name of the generated
KeptnApprepresenting your Application. All workloads that share the same value for this label are consolidated into the same
KeptnAppresource that you can generate following the instructions in Auto app discovery.
keptn.sh/container: Determines the name of the container in the workload, from which Keptn extracts the version. This applies to single- and multi-container workloads. If the given container name does not match any container in the workload no version can be determined. Note that there is no equivalent
app.kubernetes.io/annotation/label for this label.
Keptn automatically generates appropriate
resources that are used for observability,
based on whether the
annotation/label is populated:
If either of these annotations/labels are populated, Keptn automatically generates a
KeptnAppresource that includes all workloads that have the same annotation/label, thus creating a
KeptnAppresource for each defined grouping
If only the
versionannotations/labels are available (in other words, neither the
app.kubernetes.io/part-ofannotation/label is populated), Keptn creates a
KeptnAppresource for each
KeptnWorkloadand your observability output traces the individual
Keptnworkloadresources but not the combined workloads that constitute your deployed application.
Keptn Applications and Keptn Workloads
for architectural information about how
Annotations vs. labels
- Are not used to identify and select objects
- Can contain up to 262144 chars
- Metadata in an annotation can be small or large, structured or unstructured, and can include characters not permitted by labels
- Can be used to select objects and to find collections of objects that satisfy certain conditions
- Can contain up to 63 chars
- Are appropriate for identifying attributes of objects that are meaningful and relevant to users but do not directly imply semantics to the core system
Annotations take precedence over labels,
keptn.sh keys take precedence over
In other words:
- The operator first checks if the
keptn.shkey is present in the annotations, and then in the labels.
- If neither is the case, it looks for the
app.kubernetes.ioequivalent, again first in the annotations, then in the labels.
In general, annotations are more appropriate than labels for integrating Keptn with your applications because they store references, names, and version information so the 63 char limitation is quite restrictive. However, labels can be used if you specifically need them and can accommodate the size restriction.