.NET Core 2 programmatically authentcation on Keycloak example - authentication

Question

I'm trying to authenticate through a device (it's a barcode reader) that use .NET Core. I'm a newbie on .NET Core.
Now I need to write some program that gives me the possibility that given a username/password I make authentication on a Keycloak server with openidconnect. Is there some sample that shows how from a username/password string I can make the authentication programmatically?
I find a lot of examples that use .NET Core as a server that has Controllers that exposes rest API for user that have to be authenticated. But I need some example/hint to follow where the .NET Core makes the request.
Update
I could figure out (with curl) what exactly I have to do. Two calls to the Keycloak server.
call:
http://keycloakserver/auth/realms/realmName/protocol/openid-connect/token?grant_type=password&client_id=demo-app&username=username&password=password
This gives me back an object containing the access_token.
invoke the secured service adding in the header
"Authorization: bearer +access_token"
I try to develop this two calls with .NET Core.

Answer 1

I found this way to resolve it. But I'm sure is not the best way. I think there is a lot of improvement of security:
var client = new HttpClient();
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/vnd.github.v3+json"));
client.DefaultRequestHeaders.Add("User-Agent", ".NET Foundation Repository Reporter");
var values = new Dictionary<string, string>
{
{ "client_id", "myClientId" },
{ "grant_type", "password" },
{ "username", "usernaName" },
{ "password", "password" }
};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("http://domain/auth/realms/realmName/protocol/openid-connect/token", content);
var responseString = await response.Content.ReadAsStringAsync();
var responseToken = JsonConvert.DeserializeObject<ResponseToken>(responseString);
Console.WriteLine("accessToken: " + responseToken.AccessToken);
var client2 = new HttpClient();
client2.DefaultRequestHeaders.Accept.Clear();
client2.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/vnd.github.v3+json"));
client2.DefaultRequestHeaders.Add("User-Agent", ".NET Foundation Repository Reporter");
client2.DefaultRequestHeaders.Add("Authorization", "bearer "+ responseToken.AccessToken);
var dataResponse = client2.GetStreamAsync("http://serviceDomain/api/SampleData/WeatherForecasts");
var serializer = new DataContractJsonSerializer(typeof(List<Weather>));
var tempData = serializer.ReadObject(await dataResponse) as List<Weather>;
Console.WriteLine(tempData);
If you have a better solution then don't hesitate to post it.