I have a custom MembershipProvider that communicates with an external authentication service to determine if the username and password provided for a user is valid. This works great on an environment with a single frontend.

In our environment, the site files are stored on a network share, which is accessed by several frontend servers with a load balancer distributing the traffic (one of the frontend servers is the designated back office/admin server). Setup documentation. This works great using the UsersMembershipProvider that comes with Umbraco.

When I try to use my custom MembershipProvider in the load balanced environment, publish no longer updates content on the non-admin frontend servers.

I suspect the problem lies here

  <distributedCall enable="true">    
   <user>0</user><!-- <-- problem -->
    <servers>    
      <server forceProtocol="https" forcePortnumber="443" serverName="adminName">adminName</server>    
      <server forceProtocol="https" forcePortnumber="443" serverName="otherName">otherName</server>    
    </servers>    
  </distributedCall>

refers to the admin account that I set up when I created the site, when it used the UsersMembershipProvider. My custom MembershipProvider doesn't store the user's password anywhere on our site, and it would violate policy to do so.

Is there a way to have a publish user account without storing the password?

I also considered calling the UsersMembershipProvider from within my custom MembershipProvider, so the publish user could be an Umbraco user account, but everyone else could authenticate using the external auth service. However, I haven't been able to get the UsersMembershipProvider working from within my MembershipProvider.

public class MixedCustomProvider: MembershipProvider
{
    private const String UmbracoProviderName = "UmbracoUsersMembershipProvider";
    private const String CustomProviderName = "CustomMembershipProvider";

    public MembershipProvider CustomProvider
    {
        get { return Membership.Providers[CustomProviderName]; }
    }

    public MembershipProvider UmbracoProvider
    {
        get { return Membership.Providers[UmbracoProviderName]; }
    }

    public override bool ValidateUser(string username, string password)
    {
        // this.UmbracoProvider.ValidateUser returns false when given valid credentials
        return this.UmbracoProvider.ValidateUser(username, password) ||
            this.CustomProvider.ValidateUser(username, password);
    }
}

<membership defaultProvider="MixedCustomMembershipProvider" userIsOnlineTimeWindow="5">
  <providers>
    <clear />
    <add name="MixedCustomMembershipProvider" type="NS.MembershipProviders.MixedCustomProvider" minRequiredNonalphanumericCharacters="0" minRequiredPasswordLength="4" useLegacyEncoding="true" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" defaultMemberTypeAlias="NetIDAlias" passwordFormat="Hashed" />
    <add name="CustomMembershipProvider" type="NS.MembershipProviders.CustomMembershipProvider" minRequiredNonalphanumericCharacters="0" minRequiredPasswordLength="4" useLegacyEncoding="true" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" defaultMemberTypeAlias="NetIDAlias" passwordFormat="Hashed" />
    <add name="UmbracoUsersMembershipProvider" type="Umbraco.Web.Security.Providers.UsersMembershipProvider, Umbraco" minRequiredNonalphanumericCharacters="0" minRequiredPasswordLength="4" useLegacyEncoding="true" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" passwordFormat="Hashed" />
  </providers>
</membership>

  <providers>
    <users>
     <DefaultBackofficeProvider>MixedCustomMembershipProvider</DefaultBackofficeProvider>
    </users>
  </providers>