momento-functions 0.1.1

# Momento Functions
Momento Functions are how you can extend Momento.

Functions run on Momento's service hosts, and offer a powerful scripting capability.
* Use the Momento host interfaces to interact with Momento features within your cache
* Use the AWS host interfaces to use a managed, hot channel to talk to AWS resources
* Use the HTTP host interfaces to reach out to anything you want

This repository holds crates for Momento Functions guest code.

To see some of what you can do with Functions, you can look at [the examples](./momento-functions/examples/).

## Getting started
### One-time setup
* Install Rust: https://rustup.rs
* Add the Momento Functions compile target: `rustup target add wasm32-unknown-unknown`

### Make a project

`cargo init --lib hello`

### Set up build configuration
Add a file `.cargo/config.toml` that sets the build target, for convenience.
```toml
[build]
target = "wasm32-unknown-unknown"
```

### Set up `Cargo.toml`

Add this to build the right kind of artifact:
```toml
[lib]
crate-type = ["cdylib"]
```

Import the Functions support library.
```toml
[dependencies]
momento-functions       = { version = "0" }
```

### Write a Function
The simplest function is a pong response web function. You can put this in `lib.rs`.
```rust
momento_functions::post!(ping);
fn ping(_payload: Vec<u8>) -> FunctionResult<Vec<u8>> {
    Ok(b"pong".to_vec())
}
```

### Build and deploy
**Build**: `cargo build --release`

**Deploy**
```bash
curl \
  https://api.cache.$MOMENTO_CELL_HOSTNAME/functions/your_cache/ping \
  -H "authorization: $MOMENTO_API_KEY" \
  -XPUT \
  --data-binary @target/wasm32-unknown-unknown/release/hello.wasm
```

**Invoke**
```bash
curl \
  https://api.cache.$MOMENTO_CELL_HOSTNAME/functions/your_cache/ping \
  -H "authorization: $MOMENTO_API_KEY" \
  -d 'ping'
```

## Going further
From here, you should look at [the examples](./momento-functions/examples/). Momento Functions are a limited environment, but
the supported feature set is growing.