x509: failed to load system roots and no roots provided

x509 error when using HTTPS inside a Docker container

在docker容器中运行服务碰到'x509: failed to load system roots and no roots provided'的错误，原因是该服务用到了HTTPS协议，而容器里面没有相应的环境，用以下方法解决

RUN apt-get update  
RUN apt-get install -y ca-certificates