blackbox_exporter: Redirect to different HTTPS host broken

Host operating system: output of uname -a

Linux probe 4.9.50 #1 SMP Thu Sep 14 08:57:58 UTC 2017 x86_64 Intel® Xeon® CPU E5-2630 v2 @ 2.60GHz GenuineIntel GNU/Linux

blackbox_exporter version: output of blackbox_exporter -version

blackbox_exporter, version 0.9.1 (branch: HEAD, revision: 2272b4e637a591168d5b24a3943e15ac15ecba80) build user: root@27fc71dcd45b build date: 20170921-13:19:29 go version: go1.8.3

What is the blackbox.yml module config.

  http_2xx_ip4:
    prober: http
    timeout: 5s
    http:
      preferred_ip_protocol: "ip4"

Log snippet

ts=2017-09-26T11:30:56.950294668Z caller=main.go:115 module=http_2xx_ip4 target=http://foo.com level=info msg="Beginning probe" probe=http timeout_seconds=4.5
ts=2017-09-26T11:30:56.950378987Z caller=utils.go:43 module=http_2xx_ip4 target=http://foo.com level=info msg="Resolving target address" preferred_ip_protocol=ip4
ts=2017-09-26T11:30:56.950762868Z caller=utils.go:63 module=http_2xx_ip4 target=http://foo.com level=info msg="Resolved target address" ip=127.16.1.5
ts=2017-09-26T11:30:56.950794289Z caller=http.go:190 module=http_2xx_ip4 target=http://foo.com level=info msg="Making HTTP request" url=http://[127.16.1.5] host=foo.com
ts=2017-09-26T11:30:56.951863609Z caller=http.go:150 module=http_2xx_ip4 target=http://foo.com level=info msg="Received redirect" url=https://bar.com
ts=2017-09-26T11:30:56.954761741Z caller=http.go:194 module=http_2xx_ip4 target=http://foo.com level=error msg="Error for HTTP request" err="Get https://bar.com: x509: certificate is valid for www.bar.com, bar.com, not foo.com"
ts=2017-09-26T11:30:56.954796702Z caller=main.go:128 module=http_2xx_ip4 target=http://foo.com level=error msg="Probe failed" duration_seconds=0.004475863

What did you expect to see?

I’d expect a probe to succeed.

What did you see instead?

Probe fails.