Adding new Telegraf input for t128_peerpath

[shriyanshk128T]

Description

In order to translate peer_path to native telegraf we decided to create a new input telegraf which would use the existing mechanism of t128_graph and would implement conditions accordingly.

Required for all PRs:

• Signed CLA.
• Associated README.md updated.
• Has appropriate unit tests.

[gregschrock]

We need a better way to replicate this code. It's a tricky thing because the query is version dependent and we rely on the Monitoring Agent for all version dependent inputs. But it's not valid to configure an arbitrary GraphQL query in here as we will have post-processing logic specific to a query.

I think what we should have is this:

[[intpus.t128_peer_path]]
base_url = "..."
unix_socket = "..."
timeout = "..."

# versioned fields
exclude_hostname = false

And then for the implementation, it would look something like this:

type T128PeerPath struct {
	CollectorName   string            `toml:"collector_name"`
	BaseURL         string            `toml:"base_url"`
	UnixSocket      string            `toml:"unix_socket"`
	Timeout         config.Duration   `toml:"timeout"`
	ExcludeHostname bool 			  `toml:"exclude_hostname"`
	gqlCollector *t128_graphql.T128GraphQL
}

// SampleConfig returns the default configuration of the Input
func (*T128PeerPath) SampleConfig() string {
	return sampleConfig
}

//Init sets up the input to be ready for action
func (plugin *T128PeerPath) Init() error {
	// parse the config
	plugin.gqlCollector.BaseURL = plugin.BaseURL
	plugin.gqlCollector.UnixSocket= plugin.UnixSocket
	// populate the gqlCollector fields etc.

	plugin.gqlCollector.Init()
}

// Gather takes in an accumulator and adds the metrics that the Input gathers
func (plugin *T128PeerPath) Gather(acc telegraf.Accumulator) error {
	metricsChan := make(chan telegraf.Metric)
	redirectAccumulator := agent.NewAccumulator(metricChan, /* other args*/)

	go func() {
		plugin.gqlCollector.Gather(redirectAccumulator)
		close(metricsChan)
	}()

	for  metric := range metricsChan {
		// conditional logic goes here to adjust the metric and decide if it should be included, then:
		acc.AddFields(metric /*args need to adjust*/)
	}
}

[BenMatase]

Please use another method. Either figure out a way to create a graphql input internally within the peer path input or refactor the code so that they can both use it.

[gregschrock]

This seems pretty good to me, but it will require some system testing. Let's

1. Create a feature branch for the various improvements you're working on
2. Squash this change down to a single commit

[gregschrock]

Looks good if it works with the MonitoringAgentCommands.robot

[gregschrock]

what's all this? I don't think any dependencies should have been updated here.

[shriyanshk128T]

Performed a go mod tidy before pushing!

[BenMatase]

indentation is a bit weird here. Also this is to test the one filtering case. Should we add it as a seperate testcase to make it more clear?

Also about the other filtering case? Is that covered?

[shriyanshk128T]

Yes it is weird but on my vscode it shows fine I will take a look. This test case covers both!

[agrawalkaushik]

okay - this answers my question about why did we chose to run this as a native collector as opposed to using the graphql input. I guess its fine since this logic is highly custom.