Dynamometer is a tool to performance test Hadoop's HDFS NameNode. The intent is to provide a real-world environment by initializing the NameNode against a production file system image and replaying a production workload collected via e.g. the NameNode's audit logs. This allows for replaying a workload which is not only similar in characteristic to that experienced in production, but actually identical. Dynamometer will launch a YARN application which starts a single NameNode and a configurable number of DataNodes, simulating an entire HDFS cluster as a single application. There is an additional workload job run as a MapReduce job which accepts audit logs as input and uses the information contained within to submit matching requests to the NameNode, inducing load on the service.