This research paper elaborates an overview of auto scaling solutions for microservices-based applications deployed with containers. Two main features may characterize the efficiency of an autoscaler: analysis strategy launched to identify the root cause of resource saturation, and resource allocation strategy which selects the eligible components for scaling and calculates the required amount of resources. However, existing solutions do not consider the specificity of microservice architecture in their analysis and resource allocation strategies, which may lead to wrong root cause identification and unnecessary resource allocation. In this paper, we investigate and classify existing autoscalers dealing with containers in microservice context. We additionally specify the strength and the shortcomings of each category. As a conclusion, we report the challenges of such solutions and provide recommendations for future works enabling the development of microservices-aware autoscalers.