newlines break yaml syntax, prometheus fails to start

[pellywog]

description

When using some of the rules, prometheus-server fails to start with the following error message:

Aug 19 00:34:36 server prometheus-server[26365]: level=error ts=2020-08-18T22:34:36.695Z caller=main.go:764 err="error loading config from \"/etc/prometheus/prometheus.yml\": one or more errors occurred while applying the new configuration (--config.file=\"/etc/prometheus/prometheus.yml\")"

Config:

/etc/prometheus/prometheus.yml:
rule_files:
  - "rules.d/load-average.yml"

File used: https://raw.githubusercontent.com/patricktoelle/prometheus-rules/master/rules/generic/load-average.rules.yml

Expected behavior

Prometheus should start without errors.

Proposed fix

Here is a working example of the first rule in the load-average.rules.yml:

groups:
- name: load-average.rules
  rules:
  - alert: NodeLoadAverage
    expr: ((node_load5 / count without (cpu, mode) (node_cpu{mode="system"})) > 1) or (node_load5 / count without (cpu, mode) (node_cpu_seconds_total{mode="system"})) > 1
    for: 6h
    labels:
      severity: warning
      priority: P3
      paging: false
    annotations:
      summary: High Load on {{ $labels.instance }} detected
      description: "{{ $labels.instance }} Average load is above threshold (current value is: {{ $value }})"

There should be no newlines. I also tried:

foo: |
  bla
  foo
  bar

which also does not work. Only fix I found was to remove the newlines completely.

PS: The disk check for example does work, even with newlines.. I'm not sure what exactly is causing the issue - I just included all your rules at once and then noticed prometheus fails to start.