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Using Plug-ins to Extend the Runtime in Rust

The WasmEdge plug-ins are the shared libraries to provide the WasmEdge runtime to load and create host module instances. With the plug-ins, the WasmEdge runtime can be extended more easily.

Loading Plug-ins from Paths​

Developers can start using WasmEdge plug-ins by loading them from specific paths. To load plug-ins from the default paths, the following API can be used:

impl PluginManager
pub fn load(path: Option<&Path>) -> WasmEdgeResult<()>

  • The default plug-in paths will be used if the path is not given.

    • The path specified in the WASMEDGE_PLUGIN_PATH environment variable.
    • The ../plugin/ directory relative to the WasmEdge installation path.
    • The ./wasmedge/ directory under the library path if WasmEdge is installed in the /usr directory.

  • If the path is given, then

    • If the path is pointing at a file, then it indicates that a single plug-in will be loaded from the file.
    • If the path is pointing at a directory, then the method will load plug-ins from the files.

To get the names of all loaded plug-ins as returns -

pub fn names() -> Vec<String>
备注

path - A path to a plug-in file or a directory holding plug-in files. If None, then the default plug-in path will be used.

Listing Loaded Plug-ins​

Once plug-ins are loaded, developers can list the loaded plug-in names using the following approach:

pub fn names() -> Vec<String>

Getting Plug-in Context by Name​

Developers can get the plug-in context by its name using the following method:

pub fn find(name: impl AsRef<str>) -> Option<Plugin>

Here name is the name of the target plug-in.

Getting Module Instances from Plug-ins​

With the plug-in context, developers can get module instances by providing the module name:

pub fn mod_names(&self) -> Vec<String>

There may be several plug-ins in the default plug-in paths if users installed WasmEdge plug-ins by the installer.

Before using the plug-ins, developers should Loading Plug-ins from Paths.

Plug-in Module Instance​

To initialize the wasmedge_process plug-in module instance with the parameters -

pub fn init_wasmedge_process(allowed_cmds: Option<Vec<&str>>, allowed: bool)

Here, allowed_cmds is A white list of commands and allowed determines if wasmedge_process is allowed to execute all commands on the white list.