Agate is a server for the [Gemini] network protocol, built with the [Rust] programming language. Agate has very few features, and can only serve static files. It uses async I/O, and should be quite efficient even when running on low-end hardware and serving many concurrent requests.
Run cargo install agate to install agate from crates.io, or clone the [source], run cargo build --release, and then copy the compiled binary from target/release/agate to any location you want. (You can also use cargo run --release <args> to run Agate from within the source directory.)
Generate a self-signed TLS certificate and private key. For example, if you have OpenSSL 1.1 installed, you can use a command like the following. (Replace the hostname with the address of your Gemini server.)
openssl req -x509 -newkey rsa:4096 -keyout key.rsa -out cert.pem \
-days 3650 -nodes -subj "/CN=example.com"
agate <addr:port> <content_dir> <cert_file> <key_file>. For example, to listen on the standard Gemini port (1965) on all interfaces:
agate 0.0.0.0:1965 path/to/content/ cert.pem key.rsa
When a client requests the URL gemini://example.com/foo/bar, Agate will respond with the file at path/to/content/foo/bar. If there is a directory at that path, Agate will look for a file named index.gmi inside that directory.