'Return image json metadata, checksum and its blob.'

def fetch_image(self, image_id):

    resp = requests.get('{0}/v1/images/{1}/json'.format(self.registry_endpoint, image_id))
    self.assertEqual(resp.status_code, 200, resp.text)
    resp = requests.get('{0}/v1/images/{1}/json'.format(self.registry_endpoint, image_id), headers={'Authorization': ('Token    ' + self.token)})
    self.assertEqual(resp.status_code, 200, resp.text)
    json_data = resp.text
    checksum = resp.headers['x-docker-payload-checksum']
    resp = requests.get('{0}/v1/images/{1}/layer'.format(self.registry_endpoint, image_id))
    self.assertEqual(resp.status_code, 200, resp.text)
    resp = requests.get('{0}/v1/images/{1}/layer'.format(self.registry_endpoint, image_id), headers={'Authorization': ('Token    ' + self.token)})
    self.assertEqual(resp.status_code, 200, resp.text)
    return (json_data, checksum, resp.text)
