Azure SD Managed Identity auth doesn't work inside Azure Container Apps

[MattiasAng]

Describe the bug

When running VictoriaMetrics inside a Azure Container App and using Azure service discovery with Managed Identity authentication method, I am unable to get a token.

To Reproduce

Create a Container App and setup a VMAgent with Azure SD configuration and ManagedIdentity as auth method.

scrape_configs:
- job_name: test
  azure_sd_configs:
    - subscription_id: REDACTED
      authentication_method: 'ManagedIdentity'
  relabel_configs:
    - source_labels: [instance]
      regex: (.+)
      replacement: ${1}:1000
      target_label: __address__

Authentication will keep failing due to an empty token received. The actual result when using an older API version is either 401 or a response that older API versions doesn't work.
``

Version

vmagent-20230209-232200-tags-v1.87.1-0-g291c4197

Logs

2023-02-16T16:58:04.476571186Z 2023-02-16T16:58:04.476Z error VictoriaMetrics/lib/promscrape/config.go:1044 skipping azure_sd_config targets for job_name "test" because of error: cannot list virtual machines: cannot execute azure api request at /subscriptions/REDACTED/providers/Microsoft.Compute/virtualMachines?api-version=2022-03-01: unexpected status code returned from "https://management.azure.com/subscriptions/REDACTED/providers/Microsoft.Compute/virtualMachines?api-version=2022-03-01": 401; expecting 200; response body: "{\"error\":{\"code\":\"AuthenticationFailedMissingToken\",\"message\":\"Authentication failed. The 'Authorization' header is missing the access token.\"}}"

Screenshots

No response

Used command-line flags

No response

Additional information

No response

[valyala]

Re-opening the issue until the fix 6d019a3 is included in the next release of VictoriaMetrics and vmagent.

[valyala]

The fix has been included in the 1.87.2 release. Closing the issue as fixed then.

[valyala]

FYI, the fix has been included also into v1.88.0 and all the newer releases.