Added datadog agent to Ansible (#104)

[ankoure]

Motivation

Adding the Datadog agent will heavily improve the tracking and detail of our monitoring per #104.

Changes

I updated the playbook.yml file based on the configuration found in gobble. I updated all references as appropriate. However I was unsure if we needed this datadog_check block? I don't think there's python but left it as a point of reference in case it needs to point at something else.

datadog_checks:
      python:
        logs:
          - type: file
            path: "/home/ubuntu/regional-rail-explorer/regional-rail-explorer.log"
            service: "regional-rail-explorer"
            source: python
            sourcecategory: sourcecode
          - type: file
            path: "/home/ubuntu/regional-rail-explorer/s3_upload.log"
            service: "regional-rail-explorer"
            source: python
            sourcecategory: sourcecode

Testing Instructions

I think I set up the Ansible extension in VScode correctly for linting but probably is worth someone with pre-existing experience doing a double-check.

[devinmatte]

Totally wish this would work, but we currently are running into issues with the EC2 instance being too small to run a new build. So I would like to pause this until we can shrink the GTFS bundles we read into the explorer.

Once we can fix those issues then we can merge this

[nathan-weinberg]

With #177 merged can this continue?