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Context metadata

This guide walks you through the usage of context metadata in Keptn.

After reading this guide you will be able to:

  • add metadata to applications, workloads and tasks in two ways
  • add metadata information about applications to their traces

Introduction

Context metadata in Keptn is defined as all additional information that can be added to applications, workloads and tasks.

Context metadata can be added to your application in either of the following ways:

  • Use the keptn.sh/metadata annotation in any of your workloads you plan to deploy with Keptn
  • Apply a KeptnAppContext custom resource

In the following section we will explore both.

Common uses of this feature include:

  • adding a commit ID or references related to your GitOps and CI-CD tooling
  • referencing different stages and actors such as: who committed the change, in what repo, for what ticket...

Before you start

  1. Install Keptn
  2. Deploy an application, for instance, you can follow a demo app installation here

To collect traces you will require Jaeger. To visualise and inspect the traces, you can either use the Jaeger UI or Grafana.

  1. Install Grafana following the instructions in Grafana Setup or the visualization tool of your choice.
  2. Install Jaeger or a similar tool for traces following the instructions in Jaeger Setup.

Include metadata in workload traces

To enrich workload traces with custom metadata, use the keptn.sh/metadata annotation in your Deployment resource. The values specified in the annotation are added as key-value attributes to the workload trace.

Modify your workload (for example your YAML file containing a Deployment) adding an annotation with any metadata you prefer, for instance, to add information about a stage, you could add: keptn.sh/metadata: "stage=dev".

To see the changes Keptn must redeploy: increment the app.kubernetes.io/version value (ex. if you are following our getting started guide, change the version from 0.0.2 to 0.0.3) or change the keptn.sh/version value if you used the Keptn specific labels in your deployment YAML file.

This way, after the re-deployment, the workload trace will contain the stage=dev attribute.

Include metadata in application traces

Similar to the previous step, custom metadata can also be added to application traces via the KeptnAppContext CRD.

KeptnAppContext is a custom resource definition in Keptn that allows you to add metadata and links to traces for a specific application. This enables you to enrich your Keptn resources and your traces with additional information, making it easier to understand and analyze the performance of your applications.

In the .spec.metadata field you can define multiple key-value pairs, which are propagated to the application trace as attributes in the same manner as for workloads.

Note The key-value pairs that are added to the application trace are also added to each workload trace that is part of the application. If the same key is specified for both application and workload metadata attributes, values specified for the workload take precedence.

A KeptnAppContext custom resource looks like the following:

apiVersion: lifecycle.keptn.sh/v1beta1
kind: KeptnAppContext
metadata:
  name: keptndemoapp
  namespace: keptndemo
spec:
  metadata:
    commit-id: "1234"
    author: "myUser"

After applying the KeptnAppContext to your cluster, you need to increment the version of your application by modifying your deployment file and changing the value of theapp.kubernetes.io/version field (or keptn.sh/version if you used the Keptn specific labels earlier). (Alternatively you could apply the context resource before or together with the workloads.)

After deploying the KeptnAppContext resource and re-deploying the application, Keptn triggers another deployment of your application with the new context metadata, and all traces will contain the new metadata as defined in the above code example. In other words, you should be able to see the application trace as well as the workload trace contain the defined metadata as key-value attributes.

What's next?

Congratulations! You've learned how to use the KeptnAppContext CRD to add metadata to applications and their traces. This can be valuable for understanding the context of your traces and establishing connections between different versions and stages of your application.

Explore more about traces on Keptn. The paragraph on linking traces between different application also uses KeptnAppContext.

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