A Microservices application running on distributed platform such as Service Fabric is particularly hard to debug. You cannot debug the application by attaching a debugger to spot and fix the issue. Logging is a commonly used mechanism to track application behavior.
All the processes and applications running on distributed systems generate logs. The logs are usually written to files on local disk. However, since there are multiple hosts in a distributed system, managing and accessing the logs can become cumbersome. To solve this problem, a centralized logging solution is required so that multiple logs can be aggregated in a central location.
For your Service Fabric applications, you can enable collection of logs from each cluster node using Azure Diagnostics extension, which uploads logs to Azure Storage. Once you have aggregated the logs, you can use products such as Elastic Search, Azure Operations Management Suite, and so on, to derive useful information from it.