argo-cd/docs/user-guide/tool_detection.md

Tool Detection

The tool used to build an application is detected as follows:

If a specific tool is explicitly configured, then that tool is selected to create your application's manifests.

If not, then the tool is detected implicitly as follows:

• Ksonnet if there are two files, one named app.yaml and one named components/params.libsonnet.
• Helm if there's a file matching Chart.yaml.
• Kustomize if there's a kustomization.yaml, kustomization.yml, or Kustomization

Otherwise it is assumed to be a plain directory application.

References

• reposerver/repository/repository.go/GetAppSourceType
• server/repository/repository.go/listAppTypes