SigV4 FIPS STS endpoint config No Longer Working

[mohammed-uddin]

This PR: #649 was made in order to fix prometheus/prometheus#13364.

As of prometheus v3.1.0 it seems like this fix no longer works or has changed.

I used to run prometheus v2.55.1 which uses github.com/prometheus/common v0.59.1 and I specified the following

containers:
  - name: prometheus
     env:
       - name: AWS_USE_FIPS_ENDPOINT
          value: "true"

I then upgraded prometheus v.3.1.0. It uses prometeheus/common v0.61.0 which marked the sigv4 package as deprecated in #715

I've tested up to prometheus v3.4.1

And run into the following logs

"Failed to apply configuration" err="could not get SigV4 credentials: WebIdentityErr: failed to retrieve credentials\ncaused by: RequestError: send request failed\ncaused by: Post \"https://sts.us-east-1.amazonaws.com/\"

I have found that prometheus v3.0.1 which uses prometheus/common v0.60.1 is latest version that does work.

I need to upgrade prometheus but this is preventing me from upgrading to the later versions

[mehta-ankit]

Opened the Issue on Prometheus as well: prometheus/prometheus#16752