Summary

YARN services expose a set of URIs as REST APIs to fetch information related to clusters, nodes, applications, jobs, and more. The response format for these REST APIs is configurable as JSON or XML. These APIs provide useful information to monitor cluster resources and application execution. In this chapter, we covered the different REST APIs available in YARN and looked at how we can access them through web browsers and tools such as Curl. This chapter also covered the REST APIs defined for MapReduce ApplicationMaster and JobHistoryServer services. In the next chapter, we'll discuss the different scheduling algorithms defined in YARN and understand how these schedulers can easily be configured with your cluster.