Consistency between charts/ directory and requirements.yaml file

[pamiel]

There are several cases where the processing of Spray could be stopped because the content of the charts/ directory in not in line with the content of the requirements.yam file.
In particular, the following use cases are very difficult to bugfix and it would be good that Spray could perform an automatic verification:

• Several charts in the charts/ directory are matching a single entry of the requirements.yaml file => we don't know which one is executed...
• Chart present in the charts/ directory is not matching the version provided in the requirements.yaml file => something is executed, but we don't know which chart is used...
• a Chart exists in the charts/ directory but is not declared in the requirements.yaml file => as Spray calls Helm for each individual sub-chart, this additional chart is executed several times, generating duplicates objects

A check could be done by Spray using the helm dep list utility, but unfortunately this tool is not implemented properly:

• It does not make the difference between a Chart named my-chart and another one named my-chart-second and returns a wrong "too many matches": https://github.com/helm/helm/blob/release-2.15/cmd/helm/dependency.go#L157
• It does not manage the Aliasing of charts in the requirements.yaml and returns a wrong "misnamed": https://github.com/helm/helm/blob/release-2.15/cmd/helm/dependency.go#L170
• It handles the missing charts in the requirements.yaml file as a warning instead of an error: https://github.com/helm/helm/blob/release-2.15/cmd/helm/dependency.go#L242

Something inspired from this source code could be integrated in Spray...