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webhooksprometheusslackprometheus-alertmanagerprometheus-operator

Prometheus' Alertmanager Slack webhook getting "alertmanager.yaml err="unsupported scheme \"\" for URL"

I am trying to send Alertmananger alerts to Slack and I am successful in doing that with my customized template.

But now I want to send alerts to different channels and thus selecting different webhook from the configuration file and I am not able to do so and getting

component=configuration msg="Loading configuration file failed" file=/etc/alertmanager/config/alertmanager.yaml err="unsupported scheme \"\" for URL"

I am picking the webhook from a template file and the issue is mostly with the loading of the variable "slack.myorg.webhook"

Alertmanager.yaml

global:
  resolve_timeout: 5m
  slack_api_url: '{{ template "slack.myorg.webhook" . }}'
route:
  group_by: ['alertname']
  ...
  ...
  ...
templates: ['/etc/alertmanager/config/*.tmpl']

slack-myorg-template.tmpl

I will add my logic to select webhook on some labels later as of now just loading via a template

# To identify from which cluster the alerts are comming
{{ define "slack.myorg.username" }}Minikube{{ end }}

# select webhook
{{ define "slack.myorg.webhook" }}https://hooks.slack.com/services/XXX/XX/XX{{ end }}

The only issue if slack.myorg.webhook is not perfectly loading into slack_api_url by calling '{{ template "slack.myorg.webhook" . }}'.

Other things I tried

  1. Just mentioning {{ define "slack.myorg.webhook" }}https://hooks.slack.com/services/XXX/XX/XX{{ end }} doesn't cause any issue.
  2. If I do username: '{{ template "slack.myorg.webhook" . }}' under slack configuration it's not throwing error.
Solution

  • slack_api_url (as well as api_url from slack_config) don't support templating.

    https://github.com/prometheus/alertmanager/issues/2207#event-3127085200