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Version: 1.x

In-Memory Key-Value Storage Provider

This capability provider example implements wrpc:keyvalue/store@0.2.0-draft to provide key-value functionality (backed in-memory) for components that import the same interface.

👟 Run the Go project​

Clone the wasmCloud/go repository:

shell
git clone https://github.com/wasmCloud/go.git

Change directory to examples/provider/keyvalue-inmemory:

shell
cd examples/provider/keyvalue-inmemory

In addition to the standard elements of a Go project, the example directory includes the following files and directories:

  • /bindings: An auto-generated directory for Go bindings of interfaces. Users typically will not need to interact directly with the contents of this directory.
  • /wit: Directory for WebAssembly Interface Type (WIT) packages that define interfaces.
  • wasmcloud.toml: Configuration file for a wasmCloud application.

The example includes a shell script that simulates what the host does to run the provider, enabling you to test the provider without running a host.

shell
./run.sh

You can also perform each step manually:

shell
host_data='{"lattice_rpc_url": "0.0.0.0:4222", "lattice_rpc_prefix": "default", "provider_key": "keyvalue-inmemory", "link_name": "default","log_level": "debug"}' 
echo $host_data | base64 | go run ./

🛠️ Build the provider​

Build the provider:

shell
wash build

The build process will generate a .par.gz archive file in a new /build directory.

🩻 Internals​

  • main.go is a simple binary that sets up an errGroup to handle running the provider's primary requirements: executing as a standalone binary based on data received on stdin, handling RPC, and connecting to a wasmCloud lattice.
  • keyvalue.go implements the required functions to conform to wasi:keyvalue/store. If the functions as specified in the ./wit directory are not implemented, this provider will fail to build.

📖 Further reading​

For an introduction to capability providers, see the Providers Overview in the wasmCloud documentation.

For more on building providers, see the Provider Developer Guide in the wasmCloud documentation.