* A C compiler [for your platform](https://github.com/rust-lang/cc-rs#compile-time-requirements)
*`git` (to clone this repository)
**Other requirements:**
The following are optional based on your platform and needs.
*`pkg-config` — This is used to help locate system packages, such as `libssl` headers/libraries. This may not be required in all cases, such as using vendored OpenSSL, or on Windows.
* OpenSSL — Only needed on Unix-like systems and only if the `vendored-openssl` Cargo feature is not used.
This requires the development headers, which can be obtained from the `libssl-dev` package on Ubuntu or `openssl-devel` with apk or yum or the `openssl` package from Homebrew on macOS.
If using the `vendored-openssl` Cargo feature, then a static copy of OpenSSL will be built from source instead of using the system OpenSSL.
This may require additional tools such as `perl` and `make`.
On macOS, common installation directories from Homebrew, MacPorts, or pkgsrc will be checked. Otherwise it will fall back to `pkg-config`.
On Windows, the system-provided Schannel will be used instead.
LibreSSL is also supported.
**Optional system libraries:**
The build will automatically use vendored versions of the following libraries. However, if they are provided by the system and can be found with `pkg-config`, then the system libraries will be used instead:
* [`libcurl`](https://curl.se/libcurl/) — Used for network transfers.
* [`libgit2`](https://libgit2.org/) — Used for fetching git dependencies.
* [`libssh2`](https://www.libssh2.org/) — Used for SSH access to git repositories.
* [`libz`](https://zlib.net/) (aka zlib) — Used for data compression.
It is recommended to use the vendored versions as they are the versions that are tested to work with Cargo.