This patch adds a plugin that reads metrics from JSON files. This
makes it very easy to integrate with Monasca -- instead of writing
a new plugin, simply write your metrics to a file.
The advantage of this mechanism is that:
- It's simple and easy to understand
- It is asynchronous with Monasca Agent. There are two technical
advantages to this:
- Your check does not need to run at same frequency as
the agent.
- If your check blocks, this does not affect other checks
in the agent because the agent is not blocked.
- You can create the metrics as a side effect of doing other
stuff. For example, a server process can write the JSON
file while it is processing requests. With the normal plugin
architecture, you need to write code that talks to your
server process to access the metrics.
- You can write the check code in any language.
Change-Id: I1e998fa677e16cc04d46edd46d0e6433131825e7
a72f907eef