[extension/azureauth] Client authentication failed with "missing \"host\" header"

[ms-hujia]

Component(s)

No response

What happened?

Description

Before using azureauth, communication with Azure service failed with HTTP 401.

After using azureauth, exporter failed with error missing \"host\" header.

Steps to Reproduce

Add azureauth to any exporter which supports HTTP. The endpoint doesn't matter because the failure happens before actual handshake happens.

Expected Result

HTTP 200.

Actual Result

The invocation to client.Do of exporter failed with missing \"host\" header.

Collector version

0.123

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
Compiler(if manually compiled): (e.g., "go 14.2")

OpenTelemetry Collector configuration

receivers:
  filelog:
    include:
      - /home/user/test.log
exporters:
  otlphttp:
    endpoint: "https://localhost:4317"
    auth:
      authenticator: azureauth
extensions:
  azureauth:
    # add your own credential
service:
    extensions: [azureauth]
    pipelines:
      logs:
        receivers: [filelog]
        exporters: [otlphttp]

Log output

2025-05-14T09:29:51.008+0800    info    fileconsumer/file.go:267        Started watching file   {"resource": {}, "otelcol.component.id": "filelog", "otelcol.component.kind": "receiver", "otelcol.signal": "logs", "component": "fileconsumer", "path": "/home/user/test.log"}
2025-05-14T09:29:59.108+0800    info    internal/retry_sender.go:133    Exporting failed. Will retry the request after interval.        {"resource": {}, "otelcol.component.id": "otlphttp", "otelcol.component.kind": "exporter", "otelcol.signal": "logs", "error": "failed to make an HTTP request: Post \"https://localhost:4317/v1/logs\": missing \"host\" header", "interval": "4.895423665s"}
2025-05-14T09:30:04.004+0800    info    internal/retry_sender.go:133    Exporting failed. Will retry the request after interval.        {"resource": {}, "otelcol.component.id": "otlphttp", "otelcol.component.kind": "exporter", "otelcol.signal": "logs", "error": "failed to make an HTTP request: Post \"https://localhost:4317/v1/logs\": missing \"host\" header", "interval": "5.377876923s"}

Additional context

No response

[github-actions]

Pinging code owners:

• extension/azureauth: @constanca-m

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[constanca-m]

Hi @ms-hujia , can you share a a config yaml example of this?

The azureauth should be mainly used as azcore.TokenCredential. There is a bit of an issue with using with on the http:

WARNING: Currently, the token is not cached, so if you use the extension as an implementation of extensionauth.HTTPClient and extensionauth.Server, instead of azcore.TokenCredential

I am not sure if the authenticator is fully ready to be used as it is if for HTTP server, so I would really like to see which component is using and why it is failing.

I will also take a look at using the request host that you put in your PR.

[ms-hujia]

A minimum configuration which can reproduce the issue:

receivers:
  filelog:
    include:
      - /home/user/test.log
exporters:
  otlphttp:
    endpoint: "https://localhost:4317"
    auth:
      authenticator: azureauth
extensions:
  azureauth:
    # add your own credential
service:
    extensions: [azureauth]
    pipelines:
      logs:
        receivers: [filelog]
        exporters: [otlphttp]

After run echo test >> /home/user/test.log, below error logs is output:

2025-05-14T09:29:51.008+0800    info    fileconsumer/file.go:267        Started watching file   {"resource": {}, "otelcol.component.id": "filelog", "otelcol.component.kind": "receiver", "otelcol.signal": "logs", "component": "fileconsumer", "path": "/home/user/test.log"}
2025-05-14T09:29:59.108+0800    info    internal/retry_sender.go:133    Exporting failed. Will retry the request after interval.        {"resource": {}, "otelcol.component.id": "otlphttp", "otelcol.component.kind": "exporter", "otelcol.signal": "logs", "error": "failed to make an HTTP request: Post \"https://localhost:4317/v1/logs\": missing \"host\" header", "interval": "4.895423665s"}
2025-05-14T09:30:04.004+0800    info    internal/retry_sender.go:133    Exporting failed. Will retry the request after interval.        {"resource": {}, "otelcol.component.id": "otlphttp", "otelcol.component.kind": "exporter", "otelcol.signal": "logs", "error": "failed to make an HTTP request: Post \"https://localhost:4317/v1/logs\": missing \"host\" header", "interval": "5.377876923s"}

As I mentioned previously, the execution is blocked before the token request or HTTP handshake happens. So it doesn't matter what endpoint/credential used here.