private void RenewCredentials(object unused)
{
// By default, the refreshRate will continue to be
// _refreshRate, but if FetchCredentials() returns an expired credential,
// the refresh rate will be adjusted
var refreshRate = _refreshRate;
try
{
// if FetchCredentials() call were to fail, _lastRetrievedCredentials
// would remain unchanged and would continue to be returned in GetCredentials()
_lastRetrievedCredentials = FetchCredentials();
if (_lastRetrievedCredentials.IsExpiredWithin(TimeSpan.Zero))
{
// relax the refresh rate to at least 5 minutes
refreshRate = TimeSpan.FromMinutes(new Random().Next(5, 16));
}
}
catch (OperationCanceledException e)
{
_logger.Error(e, "RenewCredentials task canceled");
}
catch (Exception e)
{
// we want to suppress any exceptions from this timer task.
_logger.Error(e, FailedToGetCredentialsMessage);
}
finally
{
// re-invoke this task once after time specified by refreshRate set at beginning of this method
_credentialsRetrieverTimer.Change(refreshRate, _neverTimespan);
}
}
/// <summary>
/// Returns a copy of the most recent instance profile credentials.
/// </summary>
public override ImmutableCredentials GetCredentials()
{
CheckIsIMDSEnabled();
ImmutableCredentials credentials = null;
// Try to acquire read lock. The thread would be blocked if another thread has write lock.
if (_credentialsLock.TryEnterReadLock(_credentialsLockTimeout))
{
try
{
if (null != _lastRetrievedCredentials)
{
// if credentials are expired, we'll still return them, but log a message about
// them being expired.
if (_lastRetrievedCredentials.IsExpiredWithin(TimeSpan.Zero))
{
_logger.InfoFormat(_usingExpiredCredentialsFromIMDS);
}
return(_lastRetrievedCredentials?.Credentials.Copy());
}
}
finally
{
_credentialsLock.ExitReadLock();
}
}
// If there's no credentials cached, hit IMDS directly. Try to acquire write lock.
if (_credentialsLock.TryEnterWriteLock(_credentialsLockTimeout))
{
try
{
// Check for last retrieved credentials again in case other thread might have already fetched it.
if (null == _lastRetrievedCredentials)
{
_lastRetrievedCredentials = FetchCredentials();
}
// if credentials are expired, we'll still return them, but log a message about
// them being expired.
if (_lastRetrievedCredentials.IsExpiredWithin(TimeSpan.Zero))
{
_logger.InfoFormat(_usingExpiredCredentialsFromIMDS);
}
credentials = _lastRetrievedCredentials.Credentials?.Copy();
}
finally
{
_credentialsLock.ExitWriteLock();
}
}
if (credentials == null)
{
throw new AmazonServiceException(FailedToGetCredentialsMessage);
}
return(credentials);
}
