Expose a version method to the HTTP Rest API.

[majst01]

Add a handy http rest api call to make it possible that clients can query the installed influxdb version.

Example usage:

curl http://localhost:8086/version
{"version":"dev","gitSha":"b12783456a0c6bfcdf4da5e71a431de35e6ad56b"}

[jvshahid]

@majst01 can you please sign the CLA. The CLA can be found here

[freeformz]

Should this not be in a response header?

[jvshahid]

@freeformz what do you have in mind ? Return the version as a header with every response or just when the endpoint is hit

[damm]

I think having the version exposed in the header of every response would be fantastic. Unfortunately this pull request is not about that.

X-INFLUXDB-VERSION: 0.61.1

[majst01]

My use case was more a simple way (without then need for calling a authenticated method) to get the version of the influxdb instance. For example a client application create a new connection and prints information about the new established connection.

If the version information is only available for regular method, i need to make a call like describeDatabases just to get the version info.

Maybe we can do both:
ad a /version call, and add the X-INFLUXDB-VERSION Header to every response.

[jvshahid]

I think we should add the header for now. I don't like adding a new endpoint, since we're planning on exposing a stats endpoint. The stats endpoint will replace the ping and version endpoints, so in my opinion we shouldn't be introducing new endpoints until the stats one gets done. Thoughts ?

[majst01]

Ok, sounds like a plan. But actually there is no single place to add/set response headers in http/api.go.

[jvshahid]

See CorsHeaderHandler for an example

[majst01]

Ok, i removed the /version call and put the version info into the Header.

[torkelo]

This will be great for Grafana :)