influxdb http client (and thus telegraf) does not respect http(s)_proxy env variables

[rhruiz]

Bug report

The influx http client v2 (that is used by telegraf as well) uses does not uses the defined http_proxy, https_proxy, no_proxy environment variables and always tries to connect directly to the endpoint configured in telegraf.conf

Relevant conf:

None

System info:

Telegraf - Version 0.10.4.1
Linux valar0003 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u4 (2016-02-29) x86_64 GNU/Linux
Debian 8.3

Steps to reproduce:

1. configure your influxdb http endpoint in telegraf.conf that is directly accessible by the telegraf machine
2. set the appropriate proxy environment variable (http_proxy or https_proxy)
3. check that metrics are not pushed to influxdb

Expected behavior:

Connections to influxdb are proxyed

Actual behavior:

Connections are either refused or blocked pending on your firewall configuration and the following is logged:

016/08/05 14:55:54 Database creation failed: Get http://influxdb.****************/query?db=&q=CREATE+DATABASE+IF+NOT+EXISTS+%22*********%22: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
2016/08/05 14:55:54 Starting Telegraf (version 1.0.0-beta1)

More

The golang http itself provides some helper functions to use those variables: https://golang.org/pkg/net/http/#ProxyFromEnvironment

Moved from influxdata/telegraf#1588

[jsternberg]

Telegraf issues should be created in influxdata/telegraf rather than here.