Alertmanager Issue: http2: unsupported scheme

[Kevin Weis]

Hi,
i recently updated prometheus and alertmanager and now prometheus cant
send any alerts to alertmanager :/

I've already tried downgrading alertmanger, without success.
I did't downgrade prometheus in fear of data inconsistencies or
data-corruption.

Does anyone else had this issue and was able to solve it?
It would be great if someone could take a moment to look at this.


Prometheus version:
from version v2.28.1 to v2.32.1

Alertmanager version:
from version v0.22.2 to v0.23.0

Prometheus configuration file (snippet):
alerting:
alertmanagers:
- scheme: http
proxy_url: "https://alertmanager.domain.tld"
static_configs:
- targets:
- "alertmanager:9093"

Here is the error message logged by prometheus:

caller=notifier.go:526 level=error component=notifier
alertmanager=http://alertmanager:9093/api/v2/alerts count=1 msg="Error
sending alert" err="Post \"http://alertmanager:9093/api/v2/alerts\":
http2: unsupported scheme"


More details are on https://github.com/prometheus/prometheus/issues/10160


Thanks

--
Best regards
Kevin Weis
Pronouns: he / him

[Kevin Weis]

Hi,
just an update on this.
roidelapluie wrote a comment on the github issue suggesting that i try
to add an ENV variable to prometheus. This resolved for me the issue.


> Could you try with Prometheus running with the environment variable PROMETHEUS_COMMON_DISABLE_HTTP2=x ? That would help a lot.

--
Best regards
Kevin Weis
Pronouns: he / him