Accept parameters and credentials via environment variables

[wally007]

As discussed in python version of the Veeam exporter... " The new configuration's model allows to defined authentication model (user/passwd/attrs) identified by name; this model maybe should use user/passwd values set by env. " ... could you please enhance this GO version so that at least some parameters (such as username/password/target) can be supplied (and take precedence if they are set) via environment variables ?

[peekjef72]

Please check pre-relaese 0.3.7

Give some feedbacks so that if it is ok for you, I can merge this fix to master branch.

Doc: Extract from README

Authentication

Most of the time the access to a http api requires an authentication. It is the case for the 3 contribs (hp3par, veeam, netscaler). The exporter allows you 2 modes:

• to define the authentication parameters statically for each target.
• to define a dictionnary (map) of authentications and then to use it a target definition, or even to set it in the prometheus query.

The auth parameters are :

• mode: should be
  • basic: use http basic authentication: the "user" and "password" values will be sent in the http header request
  • token: use bearer token to authenticate
  • script: user, password will be used in the login script to access the api.
• user
• password
• token

The user, password and token values can be raw strings or retrive the values from environment variables. To use env var the value must be prefixed by "$env:" followed by the name of the variable.

  # use this auth_config to authenticate via env vars
  default:
    mode: script
    user: $env:VEEAM_EXPORTER_USER
    password: $env:VEEAM_EXPORTER_PASSWD

[wally007]

thank you

i haven't tried this GO exporter yet.

I was able add environment variables to the python version and it works great. Im more comfortable with python.

Once I get my head wrapped around GO, this httpapi exporter and how it works, I'd like to try it to fetch HPe Oneview stats and see if it work with their API as well.