To make it in shorter way you may try to make status names and class names match and then something like this:
<span class="label" ng-class="'label-'+status">{{status}}</span>
BUT...
In real life thing may be more complicated. Since you may have more statuses than bootstrap alerts and since status labels in your application not exactly the same as bootstrap class names, this may be optimal:
<span class="label" ng-class="alert_class(status)">{{status}}</span>
and in your controller:
$scope.alerts = {
'Warnings': 'label-warning',
'Ok': 'label-success',
'Critical': 'lablel-important'
};
Finally, if statuses in your code, status labels and bootstrap classes are all different, you will need more complex struture, like this:
$scope.statuses =
warning:
label: 'Warnings'
class: 'label-warning'
ok:
label: 'It`s OK'
class: 'label-success'
critical:
label: 'Something is going wrong...'
class: 'label-important'
and use it this way:
<span class="label" ng-class="statuses[status].class">{{statuses[status].label}}</span>