add logs and metrics methods

[austencollins]

This is a first pass at adding experimental logs and metrics methods.

One of the goals is to have standard inputs and outputs across logs() and metrics() methods across all components. Here is an attempt at that.

[eahefnawy]

@ac360 so this implementation doesn't actually console.log the logs. Is it meant to be used only programmatically and not via the CLI?

[austencollins]

Sorry, bad PR description. The answer is yes and no.

As always, it's up to the context to handle the outputs. In order to make it easier for contexts (cli, gui) to handle outputs, I've created a standard format for the outputs of both logs() and metrics() so that contexts can handle those outputs the same way across all components.

logs() returns an array with standard properties timestamp, message. And an object called meta for custom properties. Ideally, all components can use the same simple format for their logs() methods, since the format is very general. This enables the CLI/Template Component to define a common experience for all logs() methods, like a nice printed list of logs in the terminal.

{
  logs: [
    {
       timestamp: '2019-09-22T22:21:30.645Z',
       message: '1',
       meta: { requestId: '1981230981j1' }
    }
  ]
}

metrics() also returns an array with standard properties type, name, keys, values. Ideally, all components can use the same simple format for their metrics() methods, since the format is very general. This enables the CLI/Template Component to define a common experience for all metrics() methods. In this case, the values returned are meant to populate charts.

{
  metrics: [
    {
       type: 'keyVal', // A list of keys and values meant to populate line/bar charts
       name: 'Invocations', // The metric name
       keys: [
         '2019-09-22T22:21:30.645Z'
       ],
       values: [
         6
       ]
    }
  ]
}

[eahefnawy]

I like the idea of Context controlling logging. This is related to an issue @laardee opened here:
https://github.com/serverless/components/issues/494

[skierkowski]

Closing since I assume this is no longer relevant.