.NET: Create AWS Log Group, Log Stream, and Log Event Using .NET Core AWS SDK

There are multiple options to log data to AWS CloudWatch using .NET. The following is using the AWS SDK Amazon.CloudWatchLogs to directly add log data. The code will:

• Check to ensure the Log Group exists (optional)
• Create the Log Group if it doesn't exist (optional)
• Check if the Log Stream exists
• Create the Log Stream if it doesn't exist
• Log the message

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AmazonCloudWatchLogsClient client = null;

//using access and secret keys                
var credentials = new BasicAWSCredentials("MY_ACCESS_KEY", "MY_SECRET_KEY");
client = new AmazonCloudWatchLogsClient(credentials, Amazon.RegionEndpoint.USEast1);

//using local profile             
var credentials = new StoredProfileAWSCredentials("PROFILE_NAME");
client = new AmazonCloudWatchLogsClient(credentials, Amazon.RegionEndpoint.USEast1);            

//using execution context (ex: Lambda permissions);
client = new AmazonCloudWatchLogsClient();
				
				
//var the message to log
var message = "Something I want to log";

//log_group_name
var log_group_name = "/my-project/my-api/errors";

//log stream name - multiple logs can be added to this stream
var log_stream_name = DateTime.UtcNow.ToString("yyyy_MM_dd_HH_mm");


//the put request - used at the end but constructing it now
var put_log_events_request = new Amazon.CloudWatchLogs.Model.PutLogEventsRequest()
{
	LogEvents = new List<Amazon.CloudWatchLogs.Model.InputLogEvent>()
	{
		new Amazon.CloudWatchLogs.Model.InputLogEvent()
		{
			Message = message,
			Timestamp = DateTime.UtcNow
		}
	},
	LogGroupName = log_group_name,
	LogStreamName = log_stream_name
};


//check for log group
var describe_log_groups_request = new Amazon.CloudWatchLogs.Model.DescribeLogGroupsRequest()
{
	LogGroupNamePrefix = log_group_name,
	Limit = 1
};

var describe_log_groups_response = await client.DescribeLogGroupsAsync(describe_log_groups_request);

//create this log group?
if (describe_log_groups_response.LogGroups.Count == 0)
{
	var create_log_group_request = new Amazon.CloudWatchLogs.Model.CreateLogGroupRequest()
	{
		LogGroupName = log_group_name
	};

	var create_log_group_response = await client.CreateLogGroupAsync(create_log_group_request);
}


//get previous stream
var describe_log_streams_request = new Amazon.CloudWatchLogs.Model.DescribeLogStreamsRequest()
{
	LogGroupName = log_group_name,
	Descending = true,
	Limit = 1,
	LogStreamNamePrefix = log_stream_name,
	//nextToken: 'STRING_VALUE',
	//orderBy: "LastEventTime"
};


var describe_log_streams_response = await client.DescribeLogStreamsAsync(describe_log_streams_request);
if (describe_log_streams_response.LogStreams.Count == 0)
{
	//create new stream
	var create_log_stream_request = new Amazon.CloudWatchLogs.Model.CreateLogStreamRequest()
	{
		LogGroupName = log_group_name,
		LogStreamName = log_stream_name
	};

	var create_log_stream_response = await client.CreateLogStreamAsync(create_log_stream_request);                                                      
}
else
{
	//use current log stream
	put_log_events_request.SequenceToken = describe_log_streams_response.LogStreams[0].UploadSequenceToken;                            
}


//and finally,after all that, log the message
var put_log_events_response = await client.PutLogEventsAsync(put_log_events_request);