DDoS attacks are rampant in cloud environments and continually evolve into more sophisticated and intelligent modalities, such as low-rate DDoS attacks. But meanwhile, the cloud environment is also developing in constant. Now container technology and microservice architecture are widely applied in cloud environment and compose container-based cloud environment. Comparing with traditional cloud environments, the container-based cloud environment is more lightweight in virtualization and more flexible in scaling service. Naturally, a question that arises is whether these new features of container-based cloud environment will bring new possibilities to defeat DDoS attacks. In this paper, we establish a mathematical model based on queueing theory to analyze the strengths and weaknesses of the container-based cloud environment in defeating low-rate DDoS attack. Based on this, we propose a dynamic DDoS mitigation strategy, which can dynamically regulate the number of container instances serving for different users and coordinate the resource allocation for these instances to maximize the quality of service. And extensive simulations and testbed-based experiments demonstrate our strategy can make the limited system resources be utilized sufficiently to maintain the quality of service acceptable and defeat DDoS attack effectively in the container-based cloud environment.