example Serilog usage in a typical ETL

WarehouseTransactions.cs

public IActionResult WarehouseTransactions()
{
    dynamic logs = new ExpandoObject();
    try
    {
        using (var athenaDb = LocalDB.GetConnection())
        using (var remoteDb = RemoteDB.GetConnection())
        {
            //download ids+lastmodified timestamp for source and destination
            var sourceTransationState = athenaDb
                .Query<Transaction>(
                    @"SELECT
                        TRANSACTION_ID,
                        LAST_MODIFIED_DATE
                    FROM dbo.TRANSACTIONS
                    WHERE TRANDATE >= '2018-01-01'
                    ORDER BY CREATE_DATE DESC",
                    commandTimeout: 2400)
                .ToList();
            var destinationTransactionState = remoteDb
                .GetTransactionsState<Transaction>(DateTime.Parse("2018-01-01"))
                .ToList();

            //figure out which transaction ids are new and which are updated
            var newTransactionIds = sourceTransactionState
                .Except(destinationTransactionState, new Transaction.IdComparer())
                .Select(t => t.transaction_id)
                .OrderBy(t => t)
                .ToList();
            logs.newTransactionIdsCount = newTransactionIds.Count;
            var updatedTransactionIds = sourceTransactionState
                .Intersect(destinationTransactionState, new Transaction.IdComparer())
                .Except(destinationTransactionState, new Transaction.StatusComparer())
                .Select(t => t.transaction_id)
                .OrderBy(t => t)
                .ToList();
            logs.updatedTransactionIdsCount = updatedTransactionIds.Count;

            //fetch new+updated transactions from source
            var transactionIds = newTransactionIds
                .Concat(updatedTransactionIds)
                .ToList();
            var transactions = localDb
                .GetTransactionsByIds(transactionIds)
                .ToList();
            logs.transactionsFetchedFromLocalDB = transactions.Count;

            //convert transactions from local to remote type
            var transactionsMapped = transactions
                .Select(MapTransaction)
                .OrderBy(t => t, new Transaction.IdComparer())
                .ToList();
            logs.transactionsMapped = transactionsMapped.Count;

            //separate new transactions from updated
            var newTransactions = transactionsMapped
                .Where(t => newTransactionIds.BinarySearch(t.transaction_id) >= 0)
                .ToList();
            logs.newTransactionsCount = newTransactions.Count
            var updatedTransactions = transactionionsMappedd
                .Where(t => updatedTransactionIds.BinarySearch(t.transaction_id) >= 0)
                .ToList();
            logs.updatedTransactionsCount = updatedTransactions.Count;

            //insert new transactions
            logs.insertResults = remoteDB.BulkInsert(
                newTransactions
                "public.transactions");

            //update existing transactions
            logs.insertResults = remoteDB.BulkUpdate(
                updatedTransactions
                "public.transactions");

            //return logged data to caller
            logs.Result = "success";
            return Content(
                JsonConvert.SerializeObject((ExpandoObject)logs,Formatting.Indented),
                "application/json");
        }
    }
    catch (Exception e)
    {
        //log exception and return logged data to caller
        Logger.LogError(e, "problem warehousing transactions");

        logs.Result = "failure";
        return Content(
            JsonConvert.SerializeObject((ExpandoObject)logs,Formatting.Indented),
            "application/json");
    }
    finally
    {
        //record logged data
        Logger.LogInformation("{@log}", (ExpandoObject) logs);
    }
}