def get_url(url_base, tenant_id, user, password, type, region):
    """It get the url for a concrete service
    :param url_base: keystone url
    :param tenand_id: the id of the tenant
    :param user: the user
    :param paassword: the password
    :param type: the type of service
    :param region: the region
    """
    url = 'http://' + url_base + '/v2.0/tokens'
    headers = {'Accept': 'application/json'}
    payload = {'auth': {'tenantName': '' + tenant_id + '',
                        'passwordCredentials':
                        {'username': '' + user + '',
                        'password': '' + password + ''}}}
    try:
        response = requests.post(url, headers=headers,
                                 data=json.dumps(payload))
        response_json = response.json()
        services = response_json['access']['serviceCatalog']
    except Exception as e:
        raise Exception('Error to obtain a image ' + e.message)

    for service in services:
        if service['type'] == type and service['region'] == region:
            for endpoint in service['endpoints']:
                return endpoint['publicURL']