Scraper does not allow self-signed certificates.

[cmackenzie1]

Steps to reproduce:
List the minimal actions needed to reproduce the behavior.

1. Create a self-signed SSL certificate
2. Launch InfluxDB v2 with tls-key and tls-cert option
3. Create the Quick Start default scraper (https://influxdb.example.com:8086/metrics)

Expected behavior:

The Scraper should skip TLS verification when targeting self-signed endpoints.

Actual behavior:
Scraper fails due to TLS verification, preventing scraping metrics from endpoints with self-signed certificates.

Environment info:

• System info: Linux 5.4.0-1018-aws x86_64
• InfluxDB version: InfluxDB 2.0.1 (git: 37cc047133) build_date: 2020-11-11T03:53:31Z
• Other relevant environment details:
  • Docker Image: quay.io/influxdb/influxdb:v2.0.1

Config:

Logs:

influxdb    | ts=2020-11-16T03:54:55.660149Z lvl=error msg="Unable to gather" log_id=0QVntGm0000 error="Get \"https://influxdb.example.com:8443/metrics\": x509: certificate signed by unknown authority"
influxdb    | 2020-11-16T03:54:55.664093Z       info    http: TLS handshake error from 172.23.0.1:56070: remote error: tls: bad certificate