To make it easier, let’s start with some definitions.
And the two scenarios for today:
There's a bit of confusion surrounding how these two seemingly unrelated products work together. You’ll get an Azure AD tenant as part of your setup process of a new Azure account. That tenant’s domain will end in .onmicrosoft.com. Of course, you can add your own domains (and if you plan single sign-on, it will be a requirement), but out of the box, with zero configuration, you’ll have an .onmicrosoft.com Azure AD tenant.
That tenant’s only administrator should be the MSA you used to create your Azure subscription. This is an important distinction, because if your tenant and sub were provisioned differently, you may need to make sure your Managed Service Account (MSA) is an administrator of your Azure AD tenant.
This one is quick and easy. Provided you’ve set up your Azure AD domain (there are plenty of tutorials for doing this), it’s a two-step process. First, we need to link your directory to an Azure AD organization/tenant. Start at https://manage.windowsazure.com and head down to settings. If you’re using the same MSA that you created your Azure subscription with, your MSA should also be an administrator of your Azure AD tenant.
Under Settings & Subscriptions, you'll find a list of your subscriptions.
Now, find your subscription in the list. At the bottom you’ll see Edit Directory in the dark bar.
Find this to link your subscription to a directory.
This will bring up a new box, listing all of the Azure AD tenants (not Azure subscriptions) your MSA has access to. In your case, you may only have one. If you have more than one, pick the one that looks familiar or that contains the organizational user you want to have access to that subscription (e.g., if I want email@example.com to have access to my sub, I need to find the Azure AD tenant that has firstname.lastname@example.org).
You'll see a list of all of the Azure AD tenants MSA has access to.
Once you’ve picked yours, you’ll need to confirm the change. No sweat.
Next, we need to add the administrators.
If your Azure subscription got linked to the proper directory in the last step, this is just as easy as adding a new administrator. Under Settings > Administrators, click Add at the bottom. You should see a simple form to search for a user:
Settings > Administrators
You'll notice MSAs resolve as MSAs ...
... and organizational accounts resolve as org accounts.
Once you’ve typed in the proper account that needs access, check the boxes next to the subscription(s) you want that account to be able to co-adminster. If the name resolves, you’re finished.
Take this scenario: you're a managed service provider offering Azure resources and subscriptions as part of your management package. This implies you need to sign in to other Azure subscriptions and manage them as a co-administrator. But your organizational account is already using Azure AD, so you (and any of your employees) still need to use organizational accounts to administer customer subscriptions (instead of MSAs). Fortunately, it’s possible, but with a few more hoops.
Here are some dummy account names to make this more concrete:
First, we need to add email@example.com to the larsen.local Azure AD tenant. This sounds simple on the surface, but it's a bit trickier. In short, you need to sign in to the Azure management portal with an account that has access to both the source directory (sac.local) and the target directory (larsen.local). This is likely easiest using an MSA.
Either create or use an MSA and add that MSA as a global administrator to each Azure AD tenant, not just the Azure subscription (see instructions on how to do that).
Next, we need to add Mark (firstname.lastname@example.org) to the Larsen tenant. Head into Azure AD in the Management Portal, click Users and then Add:
Management Portal > Azure AD > Tenant > Users > Add
You’re going to want to pick "User in another Windows Azure AD directory." Next, we’ll type in email@example.com — if it works, you’ve done it successfully. You can add the user as a user, unless that user is going to be administering Azure AD as well.
If you get a message that the current user doesn’t have access to the directory, you’ll need to be sure the MSA has admin rights to both Azure AD tenants, using the info in the link a little higher.
You'll see this message if you're not using an account that's an administrator in BOTH Azure AD tenants.
At this point, you should be able to follow the directions from “Adding an organizational administrator” above, but be sure to use the new user you just added (e.g., firstname.lastname@example.org). This will allow email@example.com to administer the Azure subscription linked to the @larsens.local Azure AD tenant.