<!-- Love localstack? Please consider supporting our collective:
👉  https://opencollective.com/localstack/donate -->

# Type of request: This is a ...

[x ] bug report
[ ] feature request

# Detailed description

Not able to use the edge service to write metric data to cloudwatch via the javascript aws-sdk.

However, It **DOES** work when using the deprecated cloudwatch port.

## Expected behavior

Metric data to be visible when calling `awslocal cloudwatch list-metrics`

## Actual behavior

404 from edge service. No metric data is persisted, localstack instance logs the following info:

```
INFO:localstack.services.edge: Unable to determine forwarding port for API "monitoring" - please make sure this API is enabled via the SERVICES configuration
```

# Steps to reproduce

Run JS code in "Client code" section.
See 404 Error

## Command used to start LocalStack

`TMPDIR=/tmp/localstack docker-compose up`

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

```js
const AWS = require('aws-sdk')
const cw = new AWS.CloudWatch({
  endpoint: 'http://localhost:4566',
})

const data = {
  Namespace: 'ns',
  MetricData: [
    {
      MetricName: 'metric-name',
      Timestamp: new Date(),
      Value: 12345,
      Unit: 'Milliseconds',
      Dimensions: [
        { Name: 'Environment', Value: 'local' },
      ]
    }
  ]
}

cw.putMetricData(data, (err, data) => {
  if (err) {
      console.log('Error', err)
  } else {
      console.log('Success', JSON.stringify(data))
  }
})
```

return _python_lambda(**kwargs)
    except Exception as e:
        if print_error:
            LOG.warning('Unable to execute function: %s' % e)
def run_cmd_safe(**kwargs):
    return run_safe(run, print_error=False, **kwargs)
def run(cmd, cache_duration_secs=0, **kwargs):
    def do_run(cmd):
        return bootstrap.run(cmd, **kwargs)
    if cache_duration_secs <= 0:
        return do_run(cmd)
    hash = md5(cmd)
    cache_file = CACHE_FILE_PATTERN.replace('*', hash)
    mkdir(os.path.dirname(CACHE_FILE_PATTERN))
    if os.path.isfile(cache_file):
        
        mod_time = os.path.getmtime(cache_file)
        time_now = now()
        if mod_time > (time_now - cache_duration_secs):
            f = open(cache_file)
            result = f.read()
            f.close()
            return result
    result = do_run(cmd)
    f = open(cache_file, 'w+')
    f.write(result)
    f.close()
    clean_cache()
    return result
def clone(item):