influxdb_v2 output plugin reports write errors as outputs.influxdb instead of outputs.influxdb_v2

[mkarlesky]

System info:

Docker image telegraf:1.9.5. However, from inspecting the code it appears the latest builds of telegraf have the same bug.

Steps to reproduce:

1. Provide an incorrect URL to the outputs.influxdb_v2 plugin.

Expected behavior:

Error messages labeled with [outputs.influxdb_v2].

Actual behavior:

Error messages labeled with [outputs.influxdb].

Additional info:

The error messages below refer to the same root problem but the two statements are labeled as two different generations of output plugins when the problem was solely with the v2 plugin.

In fact, the usage scenario that triggered this bug report involved both generations of plugins. It turned out the v1 plugin was working just fine. For a short while we were rather confused in our troubleshooting because of the mislabeled error messages.

telegraf_1                    | 2019-03-25T20:02:10Z E! [outputs.influxdb] when writing to [<url snip>]: 404 Not Found: not found: path not found
telegraf_1                    | 2019-03-25T20:02:10Z E! [agent] Error writing to output [influxdb_v2]: could not write any address