### Install metrics-observer

Source: https://github.com/metrics-rs/metrics/blob/main/metrics-observer/README.md

Install the metrics-observer tool using cargo.

```bash
cargo install metrics-observer
```

--------------------------------

### Emit a counter metric

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Basic usage for emitting a counter metric. No special setup is required.

```rust
metrics::increment_counter!("my_counter");
```

--------------------------------

### Run metrics-observer with default settings

Source: https://github.com/metrics-rs/metrics/blob/main/metrics-observer/README.md

Connect to an application using the default address (127.0.0.1:5000) for metrics-exporter-tcp.

```bash
metrics-observer
```

--------------------------------

### Run metrics-observer with a custom address

Source: https://github.com/metrics-rs/metrics/blob/main/metrics-observer/README.md

Specify a custom IP address and port to connect to the metrics-exporter-tcp endpoint.

```bash
metrics-observer 192.168.1.1:5000
```

--------------------------------

### Old vs. New Metrics Recorder Approach in Rust

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Compares the previous method of using a global recorder for testing with the new, simplified approach using scoped recorders. The old method required unsafe operations and more boilerplate.

```rust
// This is the old approach, which mind you, still isn't thread-safe if you have concurrent tests
// doing the same thing:
let global = DebuggingRecorder::per_thread();
let snapshotter = global.snapshotter();

unsafe { metrics::clear_recorder(); }
global.install().expect("global recorder should not be installed");

increment_counter!("my_counter");

let snapshot = snapshotter.snapshot();
assert_eq!(snapshot.into_vec().len(), 1);

// Now let's use a scoped recorder instead:
let scoped = DebuggingRecorder::new();
let snapshotter = scoped.snappshotter();

metrics::with_local_recorder(&scoped, || {
    increment_counter!("my_counter")
});

let snapshot = snapppshotter.snapshot();
assert_eq!(snapshot.into_vec().len(), 1);
```

--------------------------------

### Emit a counter metric with target metadata

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Emit a counter metric and specify a target for filtering or context. The module path is automatically included.

```rust
metrics::increment_counter!(target: "myapp", "my_counter");
```

--------------------------------

### Old vs. New Counter Macro Usage

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Compares the previous method of registering and incrementing a counter with the new, simplified macro usage. The new approach uses a single macro per metric type and method chaining for operations.

```rust
// This is the old style of registering a metric and then performing an operation on it.
//
// We're working with a counter here.
let counter_handle = metrics::register_counter!("my_counter");
counter_handle.increment(1);

metrics::increment_counter!("my_counter");

// Now let's use the new, simplified macros instead:
let counter_handle = metrics::counter!("my_counter");
counter_handle.increment(1);

metrics::counter!("my_counter").increment(1);
```

--------------------------------

### Emit a histogram metric with target and level metadata

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Emit a histogram metric, specifying both a target and a verbosity level. The module path is automatically included.

```rust
metrics::histogram!(target: "myapp", level: metrics::Level::DEBUG, "my_histogram", 180.1);
```

--------------------------------

### Emit a gauge metric with level metadata

Source: https://github.com/metrics-rs/metrics/blob/main/metrics/RELEASES.md

Emit a gauge metric and specify a verbosity level (e.g., DEBUG). The module path is automatically included.

```rust
metrics::increment_gauge!(level: metrics::Level::DEBUG, "my_gauge", 42.2);
```

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