Build fails if OpenSSL development files are not found, making it an undocumented pre-requisite

[mzabaluev]

Crate

ibc

Summary of Bug

The build fails if OpenSSL development files cannot be located by
the build script of openssl-sys.

Version

rev 071f609

Steps to Reproduce

On a machine where OpenSSL development files are not installed, follow the guide including the documented pre-requisites and try to build Hermes.

The failure diagnostic (on Linux):

run pkg_config fail: "\"pkg-config\" \"--libs\" \"--cflags\" \"openssl\" did not exit successfully: exit status: 1\n--- stderr\nPackage openssl was not found in the pkg-config search path.\nPerhaps you should add the directory containing `openssl.pc'\nto the PKG_CONFIG_PATH environment variable\nPackage 'openssl', required by 'virtual:world', not found\n"

--- stderr
thread 'main' panicked at '

Could not find directory of OpenSSL installation, and this -sys crate cannot
proceed without this knowledge. If OpenSSL is installed and this crate had
trouble finding it, you can set the OPENSSL_DIR environment variable for the
compilation process.

Make sure you also have the development packages of openssl installed.
For example, libssl-dev on Ubuntu or openssl-devel on Fedora.

If you're in a situation where you think the directory should be found
automatically, please open a bug at https://github.com/sfackler/rust-openssl
and include information about your system as well as this message.

$HOST = x86_64-unknown-linux-gnu
$TARGET = x86_64-unknown-linux-gnu
openssl-sys = 0.9.67

', /home/mzabaluev/.cargo/registry/src/github.ghproxy.top-1ecc6299db9ec823/openssl-sys-0.9.67/build/find_normal.rs:174:5

Acceptance Criteria

If OpenSSL is required for the build, the guide should mention it.

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
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• Contributor assigned/self-assigned

[mzabaluev]

As hyper and other libraries could be switched to use rustls with feature flags, the (default) decision to use OpenSSL perhaps needs to be thought over. I can see the following benefits:

• a very mature TLS implementation;
• integration with system-installed PKI root CA certificates (system-installed libssl.so tends to be set up for that in Linux distros).