Short Paper: Highly Compatible Fast Container Startup with Lazy Layer Pull
Shotaro Gotanda, Takahiro Shinagawa · 2021
Containers are an attractive platform for developing and deploying applications. Unfortunately, in order to start up a new or updated container, the entire container image must first be pulled from a registry, increasing the waiting time for containers to actually become available. Various methods have been proposed to accelerate container startup with lazy pull of container images. However, these methods have compatibility problems with existing container ecosystems, which is a major obstacle to their deployment in production environments. In this paper, we propose a fast container startup system with lazy layer pull that is highly compatible with existing container ecosystems. Our approach is to add a boot layer with only the minimum files required for booting on top of the existing container image, and to introduce a carefully designed overlay file system called LlpFS that allows for lazy pull of layers while conforming to the specifications and de facto standards of the container ecosystem. Evaluation in practical applications showed that our system made container startup about 4.9× faster under 1 Gbps bandwidth with little performance overhead.