# Use Proxy in CKB Capsule ## Synopsis Capsule uses docker to build contracts. It supports `--env-file` to load environment variables from a file. > [!file] proxy.env > ``` > https_proxy='10.31.0.6:7890' > http_proxy='10.31.0.6:7890' > all_proxy='10.31.0.6:7890' ``` capsule --env-file proxy.env build ```