Mounted binaries

The mounted binaries section is for using external services inside a Wasm module. Each record of the form cli_tool_name = cli-tool-path within this section allows you to call a CLI tool located in the cli-tool-path directory.

Consider the following example:

toml
[[module]]
    name = "curl_adapter"
    logger_enabled = true
    [module.mounted_binaries]
    curl = "/usr/bin/curl"

toml
[[module]]
    name = "curl_adapter"
    logger_enabled = true
    [module.mounted_binaries]
    curl = "/usr/bin/curl"

Using this config with adding the following lines in your source code:

rust
#[marine]
#[link(wasm_import_module = "host")]
extern "C" {
    fn curl(cmd: Vec<String>) -> String;
}

rust
#[marine]
#[link(wasm_import_module = "host")]
extern "C" {
    fn curl(cmd: Vec<String>) -> String;
}

allows you to pass an argument as a string to the CLI tool and receive its output as a string.

This import function is a host import function, meaning that wasm_import_module must be equal to "host". Note that the signature of such functions must follow the pattern shown above: cli_tool_name(Vec<String>) -> MountedBinaryResult. This pattern reflects the Rust process API.

Then this function can be used as an ordinary Rust FFI function, but without unsafe block:

rust
#[marine]
pub fn download(url: String) -> String {
    let result = curl(vec![url]);
    String::from_utf8(result.stdout).unwrap()
}

rust
#[marine]
pub fn download(url: String) -> String {
    let result = curl(vec![url]);
    String::from_utf8(result.stdout).unwrap()
}