Helm include vs template — What’s the Difference and When to Use Each

Helm provides two commonly used functions for rendering reusable templates: template and include.
At first glance, they seem similar — both insert one template inside another — but there’s a subtle and important difference.

Let’s break it down simply and clearly.

🔍 Key Difference

📘 Example 1 template

template function just inserts content of teplate in current output.

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
spec:
  template:
    spec:
      containers:
        - name: myapp
          image: nginx
          {{- template "myapp.env" . }}

example of myapp.env:

# templates/_env.tpl
{{- define "myapp.env" -}}
env:
  - name: ENV
    value: "production"
{{- end }}

Result — content of env inserts directly.

Example 2: include

include rerturns string, which can be modified with indent, nindent or similar.

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "myapp.fullname" . }}
spec:
  template:
    spec:
      containers:
        - name: myapp
          image: nginx
          {{ include "myapp.env" . | nindent 10 }}

It is useful, when you need to control indentations or build strings:

annotations:
  checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}

When to use

Conclusion

• template — inserts the rendered template output directly into the manifest.
• include — returns it as a string, allowing for transformation and reuse.

In most real-world cases, DevOps engineers prefer include because it’s more flexible and compatible with other Helm functions

💡 Advice: always add | nindent N, to save correct indentations when using include.