I tried to use command “helm install —set app1.key1=abc my chart”, and it worked. So I read the source code helm command, eventually I figured out the root cause.

The structure of the values map should be hierarchical.

Previously the value map was created with the following code,

Values := make(map[string]interface{})

values[“app1.key1”] = “abc”

The above code isn’t correct, and it should be something as below,

Base := make(map[string]interface{})

InnerApp1 = make(map[string]interface{})

innerApp1[“key1”] = “abc”

base[“app1”] = innerApp1 

Note that I did not use helm client, instead, I use gRPC API to communicate with tiller server directly. 

I just reviewed the source code of helm client. It just configures the InstallReleaseRequest.Values with the overrides values. I followed the same logic,  so I just updated InstallReleaseRequest.Values with the override values directly.  The new source code is something as below, but it did not work either. The helm chart can be created successfully, but the POD still uses the default values defined in values.yaml in the chart instead of the override values. Can someone help to point out what’s the reason? 

func deploy(tillerEndpoint, helmChartDir, helmChartName string, overrideValues map[string]interface{}) error {

conn, err := grpc.Dial(tillerEndpoint, grpc.WithInsecure())

defer conn.Close()

tillerClient := services.NewReleaseServiceClient(conn)

helmChart, err := chartutil.Load(helmChartDir)

cc := chart.Config{ Raw:    helmChart.Values.Raw }

         If overrideValues != nil {

vals, err := chartutil.Values(overrideValues).YAML()

                cc = chart.Config{Raw: vals }

  }

req := &services.InstallReleaseRequest{

Chart:        helmChart,

Values:       &cc,

Name:         helmChartName,

Namespace:    "default",

DryRun:       false,

DisableHooks: true,

}

err = chartutil.ProcessRequirementsEnabled(req.Chart, req.Values)

err = chartutil.ProcessRequirementsImportValues(req.Chart)

_, err = tillerClient.InstallRelease(helm.NewContext(), req)

return err

}