Make `databricks configure` save only explicit fields (#973)

## Changes
Save only explicit fields to the config file
This applies to two commands: `configure` and `auth login`. 
The latter only pulls env vars in the case of the `--configure-cluster`
flag

## Tests
Manual, plus additional unit test for the `configure` command

cmd/auth/login.go

@@ -106,8 +106,13 @@ func newLoginCommand(persistentAuth *auth.PersistentAuth) *cobra.Command {
 		}
 
 		if profileName != "" {
-			cfg.Profile = profileName
-			err = databrickscfg.SaveToProfile(ctx, &cfg)
+			err = databrickscfg.SaveToProfile(ctx, &config.Config{
+				Profile:   profileName,
+				Host:      cfg.Host,
+				AuthType:  cfg.AuthType,
+				AccountID: cfg.AccountID,
+				ClusterID: cfg.ClusterID,
+			})
 			if err != nil {
 				return err
 			}

cmd/configure/configure.go

@@ -160,7 +160,11 @@ func newConfigureCommand() *cobra.Command {
 		cfg.DatabricksCliPath = ""
 
 		// Save profile to config file.
-		return databrickscfg.SaveToProfile(ctx, &cfg)
+		return databrickscfg.SaveToProfile(ctx, &config.Config{
+			Profile: cfg.Profile,
+			Host:    cfg.Host,
+			Token:   cfg.Token,
+		})
 	}
 
 	return cmd

cmd/configure/configure_test.go

@@ -106,6 +106,72 @@ func TestConfigFileFromEnvNoInteractive(t *testing.T) {
 	assertKeyValueInSection(t, defaultSection, "token", "token")
 }
 
+func TestEnvVarsConfigureNoInteractive(t *testing.T) {
+	ctx := context.Background()
+	tempHomeDir := setup(t)
+	cfgPath := filepath.Join(tempHomeDir, ".databrickscfg")
+	inp := getTempFileWithContent(t, tempHomeDir, "token\n")
+	defer inp.Close()
+	oldStdin := os.Stdin
+	t.Cleanup(func() { os.Stdin = oldStdin })
+	os.Stdin = inp
+
+	t.Setenv("DATABRICKS_HOST", "https://host")
+	t.Setenv("DATABRICKS_AUTH_TYPE", "metadata-service")
+	t.Setenv("DATABRICKS_METADATA_SERVICE_URL", "https://metadata")
+
+	cmd := cmd.New(ctx)
+	cmd.SetArgs([]string{"configure", "--token"})
+
+	err := cmd.ExecuteContext(ctx)
+	assert.NoError(t, err)
+
+	_, err = os.Stat(cfgPath)
+	assert.NoError(t, err)
+
+	cfg, err := ini.Load(cfgPath)
+	assert.NoError(t, err)
+
+	defaultSection, err := cfg.GetSection("DEFAULT")
+	assert.NoError(t, err)
+
+	assertKeyValueInSection(t, defaultSection, "host", "https://host")
+	assertKeyValueInSection(t, defaultSection, "token", "token")
+
+	// We should only save host and token for a profile, other env variables should not be saved
+	_, err = defaultSection.GetKey("auth_type")
+	assert.NotNil(t, err)
+	_, err = defaultSection.GetKey("metadata_service_url")
+	assert.NotNil(t, err)
+}
+
+func TestEnvVarsConfigureNoArgsNoInteractive(t *testing.T) {
+	ctx := context.Background()
+	tempHomeDir := setup(t)
+	cfgPath := filepath.Join(tempHomeDir, ".databrickscfg")
+
+	t.Setenv("DATABRICKS_HOST", "https://host")
+	t.Setenv("DATABRICKS_TOKEN", "secret")
+
+	cmd := cmd.New(ctx)
+	cmd.SetArgs([]string{"configure"})
+
+	err := cmd.ExecuteContext(ctx)
+	assert.NoError(t, err)
+
+	_, err = os.Stat(cfgPath)
+	assert.NoError(t, err)
+
+	cfg, err := ini.Load(cfgPath)
+	assert.NoError(t, err)
+
+	defaultSection, err := cfg.GetSection("DEFAULT")
+	assert.NoError(t, err)
+
+	assertKeyValueInSection(t, defaultSection, "host", "https://host")
+	assertKeyValueInSection(t, defaultSection, "token", "secret")
+}
+
 func TestCustomProfileConfigureNoInteractive(t *testing.T) {
 	ctx := context.Background()
 	tempHomeDir := setup(t)