Slacker: Fast Distribution with Lazy Docker Containers

Containerized applications are becoming increasingly popular, but unfortunately, current container-deployment methods are very slow. We develop a new container benchmark, HelloBench, to evaluate the startup times of 57 different containerized applications. We use HelloBench to analyze workloads in detail, studying the block I/O patterns exhibited during startup and compressibility of container images. Our analysis shows that pulling packages accounts for 76% of container start time, but only 6.4% of that data is read. We use this and other findings to guide the design of Slacker, a new Docker storage driver optimized for fast container startup. Slacker is based on centralized storage that is shared between all Docker workers and registries. Workers quickly provision container storage using backend clones and minimize startup latency by lazily fetching container data. Slacker speeds up the median container development cycle by 20x and deployment cycle by 5x.