fn_hadr_group_is_primary

use master
go
create or alter function dbo.fn_hadr_group_is_primary (@agname sysname) returns bit as
begin
    if exists (select name from sys.availability_groups) begin
        declare @primaryreplica sysname

        select
        @primaryreplica = hags.primary_replica
        from sys.dm_hadr_availability_group_states hags
        inner join sys.availability_groups ag on ag.group_id = hags.group_id
        where ag.name = @agname

        if upper(@primaryreplica) = upper(@@servername) return 1 -- primary
        else return 0 -- secondary
    end
    return 1 -- not AG server
end
go