How to solve this circular dependency problem? - oop

Question

I have two interfaces for components that each requires functionality from the other one. One that generates Oauth tokens, and another one that gets secrets from a secret provider (Azure Key Vault).
The problem is that the Token Provider needs to obtain a secret value (a password) to make its HTTP call, and the Secret Provider class needs to get a Token in order to call Azure. Chicken and Egg problem.
From the other questions I've read, one suggestion is to create a third class/interface on which the original 2 depend, but I'm not sure how that would work here.
Any help and suggestions would be appreciated. Code for all relevant classes/interfaces is shown below.
public interface ISecretProvider
{
string GetSecret(string secretName);
}
public interface ITokenProvider
{
string GetKeyVaultToken();
}
public class OktaTokenProvider : ITokenProvider
{
ISecretProvider _secretProvider;
public string GetKeyVaultToken()
{
var tokenUrl = ConfigurationManager.AppSettings["KeyVault.Token.Url"];
var clientId = ConfigurationManager.AppSettings["KeyVault.Token.ClientId"];
var clientSecret = _secretProvider.GetSecret("ClientSecret");
var scope = ConfigurationManager.AppSettings["KeyVault.Scope"];
var token = GetToken(tokenUrl, clientId, clientSecret, scope);
return token;
}
private string GetToken(string tokenUrl, string clientId, string clientSecret, string scope)
{
var clientCredentials = $"Basic {Convert.ToBase64String(Encoding.UTF8.GetBytes($"{clientId}:{clientSecret}"))}";
string responseFromServer = string.Empty;
bool success = false;
int retryCount = 0;
while (!success)
{
try
{
var tokenWebRequest = (HttpWebRequest)WebRequest.Create(tokenUrl);
tokenWebRequest.Method = "POST";
tokenWebRequest.Headers.Add($"Authorization:{clientCredentials}");
tokenWebRequest.Headers.Add("Cache-control:no-cache");
tokenWebRequest.ContentType = "application/x-www-form-urlencoded";
using (var streamWriter = new StreamWriter(tokenWebRequest.GetRequestStream()))
{
streamWriter.Write($"grant_type=client_credentials&scope={scope}");
streamWriter.Flush();
streamWriter.Close();
}
using (WebResponse response = tokenWebRequest.GetResponse())
{
using (var dataStream = response.GetResponseStream())
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
responseFromServer = reader.ReadToEnd();
reader.Close();
}
dataStream.Close();
}
response.Close();
response.Dispose();
}
success = true;
}
catch (Exception)
{
if (retryCount > 3)
{
throw;
}
else
{
retryCount++;
}
}
}
JToken token = JObject.Parse(responseFromServer);
var accessToken = $"Bearer {token.SelectToken("access_token").ToString()}";
return accessToken;
}
}
public class KeyVaultSecretProvider : ISecretProvider
{
ITokenProvider _tokenProvider;
public KeyVaultSecretProvider(ITokenProvider tokenProvider)
{
_tokenProvider = tokenProvider;
}
public string GetSecret(string secretName)
{
var KeyVaultUrl = ConfigurationManager.AppSettings[Constants.KEYVAULT_ENDPOINT];
var subscriptionKey = ConfigurationManager.AppSettings[Constants.KEYVAULT_SUBSCRIPTION_KEY];
string responseFromServer = "";
var requestedSecretUrl = $"{KeyVaultUrl}{secretName}";
var secretWebRequest = (HttpWebRequest)WebRequest.Create(requestedSecretUrl);
var accessToken = _tokenProvider.GetKeyVaultToken();
secretWebRequest.Method = "GET";
secretWebRequest.Headers.Add("authorization:" + accessToken);
secretWebRequest.Headers.Add("cache-control:no-cache");
secretWebRequest.Headers.Add("Ocp-Apim-Subscription-Key:" + subscriptionKey);
using (WebResponse response = secretWebRequest.GetResponse())
{
using (var dataStream = response.GetResponseStream())
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
responseFromServer = reader.ReadToEnd();
reader.Close();
}
dataStream.Close();
}
response.Close();
response.Dispose();
}
JToken secret = JObject.Parse(responseFromServer);
var secretValue = secret.SelectToken("Secret").ToString();
return secretValue;
}
}

Answer 1

Have a single class implement both interfaces. The two responsibilities are inter-dependent, so put them together in one class. There is nothing wrong with this.