[prometheus] Can't install prometheus agent mode

[sashalarsoo]

Describe the bug a clear and concise description of what the bug is.

Hey im trying to install prometheus helm chart with agent mode, i got the following log:
Unknown option for --enable-feature" option=agent

for these values:

server:
  defaultFlagsOverride:
  - "--enable-feature=agent"
  - "--config.file=/etc/config/prometheus.yml"

What's your helm version?

3.16.12

What's your kubectl version?

1.31.0

Which chart?

prometheus

What's the chart version?

27.52.0

What happened?

Hey im trying to install prometheus helm chart with agent mode, i got the following log:
Unknown option for --enable-feature" option=agent

for these values:

server:
  defaultFlagsOverride:
  - "--enable-feature=agent"
  - "--config.file=/etc/config/prometheus.yml"

What you expected to happen?

No response

How to reproduce it?

No response

Enter the changed values of values.yaml?

No response

Enter the command that you execute and failing/misfunctioning.

Hey im trying to install prometheus helm chart with agent mode, i got the following log:
Unknown option for --enable-feature" option=agent

for these values:

server:
  defaultFlagsOverride:
  - "--enable-feature=agent"
  - "--config.file=/etc/config/prometheus.yml"

Anything else we need to know?

No response

[zeritti]

The feature flag was removed in Prometheus release 3.0. Use the flag --agent instead:

server:
  defaultFlagsOverride:
  - "--agent"
  - "--config.file=/etc/config/prometheus.yml"

More on the agent mode in documentation. The comment in values.yaml (L244) should be corrected.