Stackdriver, a monitoring service for cloud-based applications, today announced that it has raised a $10 million Series B round led by Flybridge Capital Partners, with participation by existing investor Bain Capital Ventures and a number of angel investors. Last year, the Boston-based company raised a $5 million Series A round and today's new round, the company's co-founders Izzy Azeri and Dan Belcher told me earlier this month, will help it expand its sales and marketing efforts and allow it to add more types of analytics to its lineup. The company, the co-founders told me, wasn't actively looking for new funding, but were approached by a number of VCs after they closed the Series A round last year. Because they already saw significant customer growth for their service (they currently have about 400 users, including "dozens" of paying ones like Smugmug and 99designs), they decided to go ahead with this round. The fact that Flybridge was also an early backer of MongoDB, the Stackdriver team noted, made it an obvious choice as the lead investor for this round. Stackdriver itself is currently mostly focused on performance measurements for Amazon's cloud service. While it started out as a more general monitoring-as-a-service solution, the team quickly realized that the main pain point for developers was performance. Often, the founders told me, big teams now spend a large amount of their resources on performance monitoring and Stackdriver says it makes this significantly easier than other solutions. For $8 per resource (say a database, EC2 instance or Dynamo table), Stackdriver will create a dashboard for watching performance metrics. More importantly, though, it uses its monitoring algorithms to warn developers when anything out of the ordinary happens on their servers. The service is free for development environments with fewer than ten resources. “Before Stackdriver, we struggled to find a monitoring solution that works with dynamic cloud environments,” said Andrew Shieh, Director of Operations at Smugmug in a statement today. “Today, we use Stackdriver to ensure that our systems and infrastructure deliver the performance that our millions of users expect. Stackdriver is exactly what we would have written if we were building our own cloud monitoring product.” One of the areas the team thinks it can really improve on existing solutions is alerts. Right now, they argue, developers often use four or five different monitoring systems and they get so many alerts that "alert fatigue" can quickly set in. Even though Stackdriver is now focused on AWS and performance, the team also plans to add additional tools in the near future. Its users, for example, are already asking for a cost monitoring solution and the ability to monitor external resources. The team has, however, shelved its earlier plans to add thread detection for the time being. Besides AWS, the service also offers features for monitoring Rackspace cloud, but only a very small minority of its clients are currently using Rackspace, so it's not emphasizing this feature for now.