Can anyone help me to config the proxy authorization?

I use fiddler as my proxy server. App need to be authorized by proxy.
I have set the envirenment HTTP_PROXY=“http://xxx:8888”, but when docker connects the proxy server, server return 407 error code, the process ends. Can anyone help me to config the proxy user and passwd?

linux-l5kg:~ # export HTTP_PROXY="http://192.168.56.1:8888/"
You have new mail in /var/mail/root
linux-l5kg:~ # docker -d -D

zleil@linux-l5kg:~> sudo docker run --rm -i -t opensuse /bin/bash
root’s password:
Unable to find image ‘opensuse:latest’ locally
Pulling repository opensuse
FATA[0002] Get https://index.docker.io/v1/repositories/library/opensuse/images: authenticationrequired

I have tried to set HTTP_PROXY=“http://username:password@192.168.56.1:8888/”,but docker parse username as hostname, password as port number.

Have you tried export HTTP_PROXY=“http://username:password@192.168.56.1:8888” without the last /?`
I cannot replicate your problem.