Ability to set Request headers for IDownStreamWebAPI

[parwejp]

Dear Team,

I am not able to find out how to send request headers while using get requests on iDownStreamWebAPI. I recently got an error while calling MS graph api to add "ConsistencyLevel = eventual" header.

Microsoft Graph advanced queries Header

Describe alternatives you've considered
Have switched to ITokenAquisition implementation for now but would be nice to use IDownStreamWebAPI for it. As @rollandjb mentioned here would be possible to set request headers with pooled HttpClient with proper isolation. I am no expert but creating HttpRequestMessage could be quick fix.

If it is implemented already, could you please be kind enough to point me out to documentation?

@jennyf19 : Created the feature request as requested.

[jmprieur]

MSAL.NET 4.32.0 now supports WithExtraHttpHeaders on AcquireTokenXXX

[parwejp]

Perfect. Thanks.

[jmprieur]

@parwejp reopening because although this is supported by MSAL.NET, we still need to add support in Microsoft.Identity.Web

[jmprieur]

Design proposal:

• In TokenAcquisitionOptions, add a new ExtraHttpHeaders of type [IHeaderDictionary] that will be passed-in to the calls to MSAL.NET (using WithExtraHttpHeaders)
• In DownstreamWebApiOptions, add a new member ExtraHttpHeaders of type IHeaderDictionary. This will be used to add headers to the HttpRequest used to call the web API

Note that the two properties apply to different calls: the first during the token acquisition, and the second for the web API.

[jguldal]

Is there any workaround for adding HTTP headers to the downstream request until this feature is implemented?

[jennyf19]

Duplicate of #891

[jennyf19]

Included in the [1.22.0 release](https://github.com/AzureAD/microsoft-identity-web/releases/tag/1.22.00

[jmprieur]

@parwejp, @jguldal : the documentation is Customizing the headers (or the HttpMessageRequest) when using IDownstreamWebApi