# @crvouga/mockingbird-service-cloudwatch

> Local emulators. Real API contracts. Part of [Mockingbird](https://github.com/crvouga/mockingbird).

Stateful local emulator of Amazon CloudWatch Metrics. ESM; Node 22+ or Bun 1.2+.

## Usage

```ts
import {
  CloudWatchClient,
  ListMetricsCommand,
  PutMetricDataCommand,
} from "@aws-sdk/client-cloudwatch"
import { createServer } from "@crvouga/mockingbird-service-cloudwatch/server"

// Test setup: start the emulator and point the AWS SDK client your application uses at it.
const emulator = await createServer()
const cloudwatch = new CloudWatchClient({
  endpoint: emulator.url,
  region: "us-east-1",
  credentials: { accessKeyId: "fixture", secretAccessKey: "fixture" },
})

// Application code: ordinary SDK calls.
await cloudwatch.send(
  new PutMetricDataCommand({
    Namespace: "App",
    MetricData: [{ MetricName: "Signups", Value: 1, Unit: "Count" }],
  }),
)
const { Metrics } = await cloudwatch.send(new ListMetricsCommand({ Namespace: "App" }))
// Metrics: [{ Namespace: "App", MetricName: "Signups", Dimensions: [] }]

await emulator.close() // after the test
```

State lives in SQLite collections and participates in the shared runtime's namespace isolation,
reset, timeline, clock, journal, metrics and fault controls. No AWS account is needed.

Implemented AWS operations: `PutMetricData`, `ListMetrics`, `GetMetricStatistics`, `GetMetricData`, `PutMetricAlarm`, `DescribeAlarms`, `DeleteAlarms`, `EnableAlarmActions`, `DisableAlarmActions`, `SetAlarmState`, `PutDashboard`, `GetDashboard`, `ListDashboards`, `DeleteDashboards`.

Operations outside this list fail explicitly. This package emulates API state, not AWS infrastructure,
production quotas, billing, IAM enforcement, or provider consoles. Service-specific omissions and
oracle evidence are recorded in [the AWS coverage ledger](../../../docs/AWS_COVERAGE.md).

Run `bun run parity` with LocalStack on `http://127.0.0.1:4566`; an unavailable oracle fails the run.
No LocalStack run is recorded for this integration. The parity command is a bounded read-only SDK envelope probe, not proof of full vendor equivalence.

## Install

```sh
bun add @crvouga/mockingbird-service-cloudwatch
```

## API

- `CloudwatchAPI(options?)`: low-level AWS transport instance with `fetch` and `reset`.

- `createRuntime(options?)`: in-process Fetch API and shared state controls.
- `createServer(options?)` from the `/server` entry: HTTP listener with `url`, `runtime`, and `close()`.
- `document`, `operationIds`, and `supportedOperationIds`: generated transport contract metadata.