# Creating a Custom Scanner

pscand comes with four scanners built-in, but you may easily create your own
scanners for future extensibility. The process is simple.

1. Create your own crate
2. Implement the `Scanner` trait
3. Build, and place it into a scanner directory

See below:

## Creating your scanner crate

```toml
# scanners/scanner-custom/Cargo.toml
[package]
name = "scanner-custom"
version = "0.1.0"
edition = "2021"

[lib]
crate-type = ["cdylib"]

[dependencies]
pscand-core = { workspace = true }
```

## Implementing the `Scanner` trait

```rust
use pscand_core::scanner::Scanner;
use pscand_macros::scanner;

pub struct CustomScanner;

impl Scanner for CustomScanner {
    fn name(&self) -> &str {
        "custom"
    }

    fn collect(&self) -> Result<serde_json::Value, Box<dyn std::error::Error>> {
        // Collect your metrics
        Ok(serde_json::json!({
            "value": 42
        }))
    }
}

#[scanner]
static SCANNER: CustomScanner = CustomScanner;
```

## Building and installing

```bash
cargo build --release
# Install to a directory in PSCAND_SCANNER_DIRS (e.g., ~/.local/share/pscand/scanners)
install -Dm755 target/release/libscanner_custom.so \
    ~/.local/share/pscand/scanners/scanner-custom.so
```