Override Helm values at install time
Helm values overriding.
pass custom files with -f or --values, single keys with --set, and know precedence: defaults, then files, then --set.
editing the chart templates directly instead of supplying values.
What's really being asked
Whether you know that charts are parameterized through values and how to override those values without modifying the chart itself.
The full answer
Helm exposes configuration through values. The chart ships defaults in values.yaml, and you override them at install time in two main ways. Use -f or --values to point at one or more custom YAML files, which is the preferred approach for many or environment-specific settings: helm install myapp ./chart -f prod-values.yaml. Use --set for a few ad hoc overrides on the command line: helm install myapp ./chart --set image.tag=v2.1 --set replicaCount=3. You can combine them. Precedence matters: the chart's default values.yaml is the base, each -f file overrides earlier ones in the order given, and --set takes highest priority, overriding files. There is also --set-string for forcing string types and --set-file to read a value from a file. The templates reference these as .Values.image.tag and so on.
The mistakes people make
Editing the chart's templates or its bundled values.yaml directly, which breaks reuse and upgrades; forgetting precedence order; or thinking you must fork the chart to change a replica count.
What usually comes next
What is the precedence between multiple -f files and --set? When use --set-string? How do you inspect the final rendered values?
A concrete example
For production you run helm install api ./chart -f values-prod.yaml --set image.tag=1.4.2. The prod file sets replicaCount to 10 and resource limits, while --set pins the exact image tag from your build pipeline. The chart templates pick these up via .Values, and you can verify with helm get values api or helm template.
Interview question
If a key is set in the chart's values.yaml, again in a -f override file, and once more via --set, which value wins?
- a.The --set value, because --set has the highest precedenceCorrect
- b.The -f file, because file overrides always beat command-line flags
- c.The chart's values.yaml, because it is the canonical default
- d.It errors out due to conflicting definitions
Why? this is the answer
Helm layers values as defaults, then -f files in order, then --set on top, so --set wins. Conflicts do not error; they are resolved by this precedence.
Just read this? Test yourself on what you have been reading.
Read the original → helm.sh
- #helm
- #kubernetes
- #configuration
- #values
- #deployment
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