Wasmer Manifest (wasmer.toml)

The manifest file called wasmer.toml is required to publish to the Wasmer registry . This file contains the package’s dependencies, metadata, and command declarations.

[package]

Valid keys are:

• name (string): the package name, as <namespace>/<name>. Only required when publishing a named package to the registry; unnamed packages can be published without it.
• version (semver version ): a valid Semantic Version. Only required when publishing a named package to the registry.
• description (string)
• private (bool): mark the package as private. Defaults to false.
• license (spdx identifier ): can be MIT or GPL, for example.
• license-file (path): an override for the license file path used in publishing. Left undefined, the LICENSE file will be implicitly included in the package.
• readme (path)
• repository (url)
• homepage (url)
• entrypoint (string): The command to use by default

[package]
name = "wasmer/wasm-pack"
version = "0.7.1"
description = "A code generator that lets you treat WebAssembly modules like native dependencies."
license = "MIT" # OR license-file = "./LICENSE.md"
readme = "./README.md"
repository = "https://github.com/wasmerio/wasmer-pack"
homepage = "https://wasmer.io/"
entrypoint = "wasmer-pack"
 
# ...

[dependencies]

• "<namespace>/<name>" = "<version>"

# ...
 
[dependencies]
"sharrattj/coreutils" = "1.0.16"

Dependencies can provide modules for your own commands. To use a module from a dependency, set module to "<namespace>/<package>:<module-name>" in the command declaration.

[package]
name = "myuser/python-tool"
version = "0.1.0"
description = "Run a Python snippet from a dependency"
entrypoint = "python"
 
[dependencies]
"python/python" = "3.12"
 
[[command]]
name = "python"
module = "python/python:python"
runner = "wasi"
 
[command.annotations.wasi]
main-args = ["-c", "print('Hello from a dependency module')"]

[[module]]

• name (string) required
• source (path) required: path to the .wasm file
• abi (string): the ABI the module targets. One of "wasi", "wasm4", or "none".

# ...
 
[module]
name = "wasmer-pack"
source = "./target/wasm32-unknown-unknown/release/wasmer-pack.wasm"

[module.bindings]

Declares the interface definitions used to generate bindings for this module. Bindings come in two forms, WAI  or WIT , and exactly one of wai-version or wit-bindgen must be set.

WAI form:

• wai-version (string): The version of WAI  being targeted (e.g. "0.2.0")
• exports (string): The path to a *.wai file defining the interface exposed by the module
• imports (string[]): A list of *.wai files defining functionality the host will provide to the module

[[module]]
name = "wasmer-pack"
...
 
[module.bindings]
wai-version = "0.2.0"
exports = "./wasmer-pack.wai"
imports = ["http-client.wai", "logging.wai"]

WIT form:

• wit-bindgen (string): The version of wit-bindgen being targeted (e.g. "0.1.0")
• wit-exports (string): The path to a *.wit file defining the interface exposed by the module

[module.bindings]
wit-bindgen = "0.1.0"
wit-exports = "./exports.wit"

[[command]]

• name required (string): the name of the command, invoked via wasmer run . --command=<command-name>
• module required (string): the name of the module this command is running.
• runner required (string): a URL or well-known name for the runner used to execute this command (e.g. "wasi", "wcgi", "wasm4")
• annotations: free-form command metadata that will be passed through to the runner as-is

Note that the module may be either the name of a [[module]] in the current wasmer.toml, or it might come from a dependency. For example, module = "python/python:python" indicates the command uses the python module from the package’s python/python dependency.

It is valid (and often preferable) for a [command] and [module] to have the same name.

# ...
 
[[command]]
name = "wasmer-pack"
module = "wasmer-pack"
runner = "wasi"

[command.annotations.wasi]

Annotations specific to the WASI runner.

• main-args (string[]): command-line arguments passed to a command on startup
• env (string[]): a list of key=value environment variables passed through to the command on startup

[[command]]
name = "wasmer-pack"
...
 
[command.annotations.wasi]
main-args = ["--verbose"]
env = ["RUST_LOG=debug"]

[command.annotations.wcgi]

• dialect (string): the name of the CGI dialect being implemented. May be either "rfc-3875" (the default) or "wcgi".

The WCGI runner also respects the [command.annotations.wasi] annotations.

[[command]]
name = "wasmer-pack"
...
 
[command.annotations.wcgi]
dialect = "wcgi"

[fs]

• "location/on/wasm"="location/on/publishing/machine": bundle local files into the package and make them available on the WASI filesystem

# ...
 
[fs]
"/cpython" = "./build"
"/lib/python3.12" = "./lib"