# Use Proxy in CKB Capsule
## Metadata
**Status**:: #x
**Zettel**:: #zettel/literature
**Created**:: [[2023-09-18]]
## 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
```