Connect-Graph: Cert based authentication errors, documentation and error handling

[FriedrichWeinmann]

Just tried to implement an application based workflow using the module and was facing an issue that was driving me nuts:
No matter what I tried, when running Connect-Graph it would complain about the parameter certificate being null.

I finally managed to solve the problem (after tracing the sourcecode), so here's what I learned from my ordeal:

• The command is in desperate need for some help. Happy to help with that and some automation behind it, assuming I can find the time.
• It looks for the certificate in the user store, but not in the computer store. This is a handicap for when I set up a task that is designed to run under a different account than my test account.
• The parameter "CertificateName" should probably be renamed to "CertificateSubject"
• Some front-up input validation during begin would allow a lot more user-friendly error messages.

On my feature-wishlist for the command:

• Add a -Certificate parameter to the command, that accepts a X509Certificate2 object.
• Add a -CertificatePath and a -CertificatePassword parameter, to enable pointing at a PFX file.
• Remove the need to provide both CertificateName and CertificateThumbprint. It's redundant and if the user can provide the thumbprint, it doesn't use the name anyway.
  AB#7442

[DSotnikov]

So if I want to use certificate to authenticate when connecting to Microsoft Graph, am I right in understanding that the flow needs to be the following:

1. Generate a certificate (can be self-signed)
2. Register an app in Azure with that certificate and grant it permissions: basically steps 1 & 2 from https://docs.microsoft.com/en-us/graph/auth-v2-service
3. Store that certificate in the user store on the machine on which I run my scheduled task as described above by @FriedrichWeinmann

[georgend]

#102

[peombwa]

#440 added this in 1.2.0.

[SjoerdV]

Examples of 'in the field' Modules that already have a great App-only authentication experience:

• https://docs.microsoft.com/en-us/powershell/module/exchange/connect-exchangeonline?view=exchange-ps#example-3
• https://pnp.github.io/powershell/cmdlets/Connect-PnPOnline.html#example-6
• https://github.com/andlin03/EasyGraph#connect