Monitor Elasticsearch Ingestors

[bkez322]

This PR aims to do the following:

• Enables Slack Notifications for when new versions of ingestor_exporter are available
• Adds new bosh job "ingestor_exporter" - intended to be ran on ingestor VMs as part of Elasticsearch deployments. Exports firehose-to-syslog metrics on default port 9495. Currently using ingestor_exporter v2.2.0.
• Adds new bosh job "ingestor_dashboards". Contains a Grafana JSON dashboard intended to be placed in the "Elasticsearch" folder. The dashboard utilizes metrics exported by the ingestor_exporter.
• Modifies the "monitor-bosh.yml" ops-file to automatically begin scraping ingestor_exporter metrics on port 9495.
• Adds new ops-file "monitor-elasticsearch-ingestors.yml". This adds an ingestor dashboard to Grafana. Currently there are no Prometheus alerts, but these may be added in the future (might be good to have an alert for Messages in Buffer overfilling- for example).

[frodenas]

Thanks @bkez322! Added the blob at 0289987.

[bkez322]

That was super quick, thank you!

Do you have any rough estimate for when you think this will make it into a new release?

[frodenas]

@bkez322 Most likely at the end of this week.