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When the Helm abstraction is limiting Gimlet specific content

Helm charts need to cater to many different deployment options. At the far end of the spectrum, a Helm chart must template every single Kubernetes manifest field. In practice, many Helm charts fall into this trap, but a Helm chart maintainer must know where to draw the line.

We drew the line at the 30 most common deployment variations with OneChart.

If your company outgrows it, you always have the option to fork it and maintain your supported feature set.

Gimlet also allows for Helm chart post-processing. You can place a Kustomize patch in the Gimlet environment manifest file and have it applied on the rendered manifest that comes out of Helm. Eventually, you can also use raw Kubernetes yamls, if none of the abstractions and escape hatches work for you.

When the Helm abstraction is limiting​

It is important for a developer platform not to stand in the way of experienced users. Gimlet provides convenient escape hatches for situations when the abstraction is limiting.

In manifesting, Gimlet's chosen abstraction is the Helm chart. Helm charts cannot cater to all kinds of customizations, so Gimlet provides two alternative ways for manifests.

Using Helm charts​

app: myapp
env: staging
namespace: my-team
chart:
  repository: https://chart.onechart.dev
  name: onechart
  version: 0.32.0
values:
  replicas: 1
  image:
    repository: myapp
    tag: "{{ .GIT_SHA }}"

Using raw manifests​

app: myapp
env: staging
namespace: my-team
manifests: |
  ---
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: myapp
    namespace: my-team
  spec:
    replicas: 1
    selector:
      matchLabels:
        app.kubernetes.io/name: onechart
        app.kubernetes.io/instance: myapp
    template:
      metadata:
        labels:
          app.kubernetes.io/name: onechart
          app.kubernetes.io/instance: myapp
      spec:
        containers:
          - name: myapp
            image: "myapp:{{ .GIT_SHA }}"

Using Helm charts with a Kustomize escape hatch​

app: myapp
env: staging
namespace: my-team
chart:
  repository: https://chart.onechart.dev
  name: onechart
  version: 0.32.0
values:
  replicas: 1
  image:
    repository: myapp
    tag: 1.1.0
strategicMergePatches: |
  ---
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: myapp
    namespace: my-team
  spec:
    template:
      spec:
        containers:
        - name: myapp
          volumeMounts:
            - name: azure-file
              mountPath: /azure-bucket
      volumes:
        - name: azure-file
          azureFile:
            secretName: my-azure-secret
            shareName: my-azure-share
            readOnly: false

You can find more examples at: https://github.com/gimlet-io/gimlet-cli/tree/main/examples