TrueFoundry allows you to tweak the most common parameters of the deployment through the service spec. However, there might be situations in which you might want to override some fields that are not exposed in the TrueFoundry Service spec. You can then use Kustomize to add, patch or delete the Kubernetes resources that TrueFoundry deploys on the cluster. Kustomize enables you to
  • Patch the rendered Kubernetes resources generated by the TrueFoundry Application. E.g. Adding extra annotations for Prometheus / Datadog
  • Add extra Kubernetes resources along with your TrueFoundry Application. E.g. Adding extra ConfigMap, Secret, Istio VirtualService, etc
Truefoundry doesn’t allow you to use Kustomize to create cluster level resources like ClusterRole, ClusterRoleBinding or non-namespace scoped resources like EnvoyFilter and WasmPlugin. You can create these resources only if you are cluster admin for the cluster, else the deployment will fail. This prevents the scenario where a user who has access to a certain workspace can create cluster level resources and impact other workloads in the cluster.

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Using Kustomize for your application

You can add patches and resources using the kustomize field in the service deployment form. There are two sections:
  1. Patch: We define an array of patches to be applied to the rendered Kubernetes resources generated by the TrueFoundry Application. For e.g. this Kustomize patch adds Prometheus scraping annotations to the pod template metadata of a Deployment named “my-service”. Specifically, it configures Prometheus to scrape metrics from port 8000 by setting prometheus.io/port to “8000” and enabling scraping with prometheus.io/scrape set to “true”.
patches:
  - target:
      group: apps
      version: v1
      kind: Deployment
      name: my-service
    patch: |
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: my-service
      spec:
        template:
          metadata:
            annotations:
              prometheus.io/port: "8000"
              prometheus.io/scrape: "true"
  1. Additional Manifest: This section allows you to add new Kubernetes resources to the deployment. The example below adds a new ConfigMap to the deployment.
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-simple-config
  namespace: default
data:
  greeting: "Hello from ConfigMap!"
  color: "blue"
This is how it looks after filling up the Kustomize section:
Once you deploy the application, you can view the generated Kubernetes resources in the Application Spec Tab and then selecting Applied K8s Manifest
This should reflect the kustomized resources after your Kustomize patches and additions are applied.

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Commonly Used Kustomize Patches

Here are some commonly used Kustomize patches that you can use to customize your application: