def AddInstanceTags(r, instance, tags, dry_run=False):
    """
    Adds tags to an instance.

    @type instance: str
    @param instance: instance to add tags to
    @type tags: list of str
    @param tags: tags to add to the instance
    @type dry_run: bool
    @param dry_run: whether to perform a dry run

    @rtype: int
    @return: job id
    """
    query = {'tag': tags, 'dry-run': dry_run}
    return r.request('put', '/2/instances/%s/tags' % instance, query=query)
