Use snap cli rather than custom snap-tool (LP: #1864252)
snap-tool was added to support a deprecate cohort-key feature of the snap store. Recent changes in snap assertions have added additional fields which snap-tool is not retrieving. This resulted in snap install failures on first boot. This patch removes snap-tool and returns to using the snap cli. This ensures snap downloads will function without odd incompatibilities.sil2100/appliance-images
Robert C Jennings
5 years ago
parent
d516e68807
commit
ec954a80b9
@ -1,603 +0,0 @@
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#!/usr/bin/python3
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#-*- encoding: utf-8 -*-
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"""
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This script can be used instead of the traditional `snap` command to download
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snaps and accompanying assertions. It uses the new store API (v2) which allows
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creating temporary snapshots of the channel map.
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To create such a snapshot run
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snap-tool cohort-create
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This will print a "cohort-key" to stdout, which can then be passed to future
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invocations of `snap-tool download`. Whenever a cohort key is provided, the
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store will provide a view of the channel map as it existed when the key was
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created.
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"""
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from textwrap import dedent
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import argparse
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import base64
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import binascii
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import getopt
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import hashlib
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import json
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import os
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import re
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import shutil
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import subprocess
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import sys
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import time
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import urllib.error
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import urllib.request
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EXIT_OK = 0
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EXIT_ERR = 1
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class SnapError(Exception):
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"""Generic error thrown by the Snap class."""
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pass
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class SnapCraftError(SnapError):
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"""Error thrown on problems with the snapcraft APIs."""
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pass
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class SnapAssertionError(SnapError):
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"""Error thrown on problems with the assertions API."""
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pass
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class ExpBackoffHTTPClient:
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"""This class is an abstraction layer on top of urllib with additional
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retry logic for more reliable downloads."""
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class Request:
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"""This is a convenience wrapper around urllib.request."""
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def __init__(self, request, do_retry, base_interval, num_tries):
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"""
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:param request:
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An urllib.request.Request instance.
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:param do_retry:
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Whether to enable the exponential backoff and retry logic.
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:param base_interval:
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The initial interval to sleep after a failed attempt.
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:param num_tries:
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How many attempts to make.
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"""
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self._request = request
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self._do_retry = do_retry
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self._base_interval = base_interval
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self._num_tries = num_tries
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self._response = None
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def open(self):
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"""Open the connection."""
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if not self._response:
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self._response = self._retry_urlopen()
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def close(self):
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"""Close the connection."""
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if self._response:
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self._response.close()
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self._response = None
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def data(self):
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"""Return the raw response body."""
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with self:
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return self.read()
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def json(self):
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"""Return the deserialized response body interpreted as JSON."""
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return json.loads(self.data(), encoding="utf-8")
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def text(self):
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"""Return the response body as a unicode string."""
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encoding = "utf-8"
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with self:
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content_type = self._response.getheader("Content-Type", "")
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if content_type == "application/json":
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encoding = "utf-8"
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else:
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m = re.match(r"text/\S+;\s*charset=(?P<charset>\S+)",
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content_type)
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if m:
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encoding=m.group("charset")
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return self.read().decode(encoding)
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def read(self, size=None):
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"""Read size bytes from the response. If size if not set, the
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complete response body is read in."""
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return self._response.read(size)
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def __enter__(self):
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"""Make this class a context manager."""
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self.open()
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return self
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def __exit__(self, type, value, traceback):
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"""Make this class a context manager."""
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self.close()
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def _retry_urlopen(self):
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"""Try to open the HTTP connection as many times as configured
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through the constructor. Every time an error occurs, double the
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time to wait until the next attempt."""
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for attempt in range(self._num_tries):
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try:
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return urllib.request.urlopen(self._request)
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except Exception as e:
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if isinstance(e, urllib.error.HTTPError) and e.code < 500:
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raise
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if attempt >= self._num_tries - 1:
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raise
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sys.stderr.write(
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"WARNING: failed to open URL '{}': {}\n"
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.format(self._request.full_url, str(e))
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)
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else:
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break
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sleep_interval = self._base_interval * 2**attempt
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sys.stderr.write(
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"Retrying HTTP request in {} seconds...\n"
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.format(sleep_interval)
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)
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time.sleep(sleep_interval)
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def __init__(self, do_retry=True, base_interval=2, num_tries=8):
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"""
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:param do_retry:
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Whether to enable the retry logic.
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:param base_interval:
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The initial interval to sleep after a failed attempt.
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:param num_tries:
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How many attempts to make.
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"""
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self._do_retry = do_retry
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self._base_interval = base_interval
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self._num_tries = num_tries if do_retry else 1
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def get(self, url, headers=None):
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"""Create a GET request that can be used to retrieve the resource
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at the given URL.
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:param url:
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An HTTP URL.
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:param headers:
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A dictionary of extra headers to send along.
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:return:
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An ExpBackoffHTTPClient.Request instance.
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"""
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return self._prepare_request(url, headers=headers)
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def post(self, url, data=None, json=None, headers=None):
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"""Create a POST request that can be used to submit data to the
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endpoint at the given URL."""
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return self._prepare_request(
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url, data=data, json_data=json, headers=headers
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)
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def _prepare_request(self, url, data=None, json_data=None, headers=None):
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"""Prepare a Request instance that can be used to retrieve data from
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and/or send data to the endpoint at the given URL.
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:param url:
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An HTTP URL.
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:param data:
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Raw binary data to send along in the request body.
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:param json_data:
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A Python data structure to be serialized and sent out in JSON
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format.
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:param headers:
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A dictionary of extra headers to send along.
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:return:
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An ExpBackoffHTTPClient.Request instance.
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"""
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if data is not None and json_data is not None:
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raise ValueError(
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"Parameters 'data' and 'json_data' are mutually exclusive."
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)
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if json_data:
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data = json.dumps(json_data, ensure_ascii=False)
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if headers is None:
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headers = {}
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headers["Content-Type"] = "application/json"
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if isinstance(data, str):
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data = data.encode("utf-8")
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return ExpBackoffHTTPClient.Request(
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urllib.request.Request(url, data=data, headers=headers or {}),
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self._do_retry,
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self._base_interval,
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self._num_tries
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)
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class Snap:
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"""This class provides methods to retrieve information about a snap and
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download it together with its assertions."""
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def __init__(self, name, channel="stable", arch="amd64", series=16,
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cohort_key=None, assertion_url="https://assertions.ubuntu.com",
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snapcraft_url="https://api.snapcraft.io", **kwargs):
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"""
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:param name:
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The name of the snap.
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:param channel:
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The channel to operate on.
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:param arch:
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The Debian architecture of the snap (e.g. amd64, armhf, arm64, ...).
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:param series:
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The device series. This should always be 16.
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:param cohort_key:
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A cohort key to access a snapshot of the channel map.
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"""
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self._name = name
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self._channel = channel
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self._arch = arch
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self._series = series
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self._cohort_key = cohort_key
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self._assertion_url = assertion_url
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self._snapcraft_url = snapcraft_url
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self._details = None
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self._assertions = {}
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@classmethod
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def cohort_create(cls):
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"""Get a cohort key for the current moment. A cohort key is valid
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across all snaps, channels and architectures."""
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return Snap("core")\
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.get_details(cohort_create=True)\
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.get("cohort-key")
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def download(self, download_assertions=True):
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"""Download the snap container. If download_assertions is True, the
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corresponding assertions will be downloaded, as well."""
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snap = self.get_details()
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snap_name = snap["name"]
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snap_revision = snap["revision"]
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publisher_id = snap["publisher"]["id"]
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snap_download_url = snap["download"]["url"]
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snap_byte_size = snap["download"]["size"]
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filename = snap_name + "_" + str(snap_revision)
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snap_filename = filename + ".snap"
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assert_filename = filename + ".assert"
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skip_snap_download = False
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if os.path.exists(snap_filename) and os.path.getsize(snap_filename) \
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== snap_byte_size:
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skip_snap_download = True
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headers = {}
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if os.environ.get("SNAPPY_STORE_NO_CDN", "0") != "0":
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headers.update({
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"X-Ubuntu-No-Cdn": "true",
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"Snap-CDN": "none",
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})
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if not skip_snap_download:
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http_client = ExpBackoffHTTPClient()
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response = http_client.get(snap_download_url, headers=headers)
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with response, open(snap_filename, "wb+") as fp:
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shutil.copyfileobj(response, fp)
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if os.path.getsize(snap_filename) != snap_byte_size:
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raise SnapError(
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"The downloaded snap does not have the expected size."
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)
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if not download_assertions:
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return
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required_assertions = [
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"account-key",
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"account",
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"snap-declaration",
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"snap-revision",
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]
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if publisher_id == "canonical":
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required_assertions.remove("account")
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for assertion_name in required_assertions:
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attr_name = "get_assertion_" + assertion_name.replace("-", "_")
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# This will populate self._assertions[<assertion_name>].
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getattr(self, attr_name)()
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with open(assert_filename, "w+", encoding="utf-8") as fp:
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fp.write("\n".join(self._assertions[a] for a in
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required_assertions))
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def get_details(self, cohort_create=False):
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"""Get details about the snap. On subsequent calls, the cached results
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are returned. If cohort_create is set to True, a cohort key will be
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created and included in the result."""
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if self._details and not cohort_create:
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return self._details
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if self.is_core_snap() and self._channel.startswith("stable/ubuntu-"):
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sys.stderr.write(
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"WARNING: switching channel from '{}' to 'stable' for '{}' "
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"snap.\n".format(self._channel, self._name)
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)
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self._channel = "stable"
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path = "/v2/snaps/refresh"
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data = {
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"context": [],
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"actions": [
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{
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"action": "download",
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"instance-key": "0",
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"name": self._name,
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"channel": self._channel,
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}
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],
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"fields": [
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"base",
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"created-at",
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"download",
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"license",
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"name",
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"prices",
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"publisher",
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"revision",
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"snap-id",
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"summary",
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"title",
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"type",
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"version",
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],
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}
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# These are mutually exclusive.
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if cohort_create:
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data["actions"][0]["cohort-create"] = True
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elif self._cohort_key:
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data["actions"][0]["cohort-key"] = self._cohort_key
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try:
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response_dict = self._do_snapcraft_request(path, json_data=data)
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except SnapCraftError as e:
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raise SnapError("failed to get details for '{}': {}"
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.format(self._name, str(e)))
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snap_data = response_dict["results"][0]
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if snap_data.get("result") == "error":
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raise SnapError(
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"failed to get details for '{}': {}"
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.format(self._name, snap_data.get("error", {}).get("message"))
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)
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# Have "base" initialized to something meaningful.
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if self.is_core_snap():
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snap_data["snap"]["base"] = ""
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elif snap_data["snap"].get("base") is None:
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snap_data["snap"]["base"] = "core"
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# Copy the key into the snap details.
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if "cohort-key" in snap_data:
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snap_data["snap"]["cohort-key"] = snap_data["cohort-key"]
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if "error" in snap_data:
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raise SnapError(
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"failed to get details for '{}' in '{}' on '{}': {}"
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.format(self._name, self._channel, self._arch,
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snap_data["error"]["message"])
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)
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self._details = snap_data["snap"]
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return self._details
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def get_assertion_snap_revision(self):
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"""Download the snap-revision assertion associated with this snap. The
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assertion is returned as a string."""
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if "snap-revision" in self._assertions:
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return self._assertions["snap-revision"]
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snap = self.get_details()
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snap_sha3_384 = base64.urlsafe_b64encode(
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binascii.a2b_hex(snap["download"]["sha3-384"])
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).decode("us-ascii")
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data = self._do_assertion_request("/v1/assertions/snap-revision/{}"
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.format(snap_sha3_384))
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self._assertions["snap-revision"] = data
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return data
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def get_assertion_snap_declaration(self):
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"""Download the snap-declaration assertion associated with this snap.
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The assertion is returned as a string."""
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if "snap-declaration" in self._assertions:
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return self._assertions["snap-declaration"]
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snap = self.get_details()
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series = self._series
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snap_id = snap["snap-id"]
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data = self._do_assertion_request(
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"/v1/assertions/snap-declaration/{}/{}"
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.format(series, snap_id))
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self._assertions["snap-declaration"] = data
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return data
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def get_assertion_account(self):
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"""Download the account assertion associated with this snap. The
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assertion is returned as a string."""
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if "account" in self._assertions:
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return self._assertions["account"]
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snap = self.get_details()
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publisher_id = snap["publisher"]["id"]
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data = self._do_assertion_request("/v1/assertions/account/{}"
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.format(publisher_id))
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self._assertions["account"] = data
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return data
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def get_assertion_account_key(self):
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"""Download the account-key assertion associated with this snap. The
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assertion will be returned as a string."""
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if "account-key" in self._assertions:
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return self._assertions["account-key"]
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declaration_data = self.get_assertion_snap_declaration()
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sign_key_sha3 = None
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for line in declaration_data.splitlines():
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if line.startswith("sign-key-sha3-384:"):
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sign_key_sha3 = line.split(":")[1].strip()
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data = self._do_assertion_request("/v1/assertions/account-key/{}"
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.format(sign_key_sha3))
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self._assertions["account-key"] = data
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return data
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def is_core_snap(self):
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return re.match(r"^core\d*$", self._name) != None
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def _do_assertion_request(self, path):
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url = self._assertion_url + path
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headers = {
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"Accept": "application/x.ubuntu.assertion",
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}
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http_client = ExpBackoffHTTPClient()
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try:
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with http_client.get(url, headers=headers) as response:
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return response.text()
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except urllib.error.HTTPError as e:
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raise SnapAssertionError(str(e))
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def _do_snapcraft_request(self, path, json_data=None):
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url = self._snapcraft_url + "/" + path
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headers = {
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"Snap-Device-Series": str(self._series),
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"Snap-Device-Architecture": self._arch,
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}
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http_client = ExpBackoffHTTPClient()
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try:
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response = http_client.post(url, json=json_data, headers=headers)
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with response:
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return response.json()
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except urllib.error.HTTPError as e:
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raise SnapCraftError(str(e))
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class SnapCli:
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def __call__(self, args):
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"""Parse the command line arguments and execute the selected command."""
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||||
options = self._parse_opts(args)
|
||||
|
||||
try:
|
||||
options.func(getattr(options, "snap", None), **vars(options))
|
||||
except SnapError as e:
|
||||
sys.stderr.write("snap-tool {}: {}\n".format(
|
||||
options.command, str(e)))
|
||||
return EXIT_ERR
|
||||
return EXIT_OK
|
||||
|
||||
@staticmethod
|
||||
def _get_host_deb_arch():
|
||||
result = subprocess.run(["dpkg", "--print-architecture"],
|
||||
stdout=subprocess.PIPE, stderr=subprocess.PIPE,
|
||||
universal_newlines=True, check=True)
|
||||
|
||||
return result.stdout.strip()
|
||||
|
||||
def _parse_opts(self, args):
|
||||
main_parser = argparse.ArgumentParser()
|
||||
subparsers = main_parser.add_subparsers(dest="command")
|
||||
|
||||
parser_cohort_create = subparsers.add_parser("cohort-create",
|
||||
help="Create a cohort key for the snap store channel map.")
|
||||
parser_cohort_create.set_defaults(func=self._cohort_create)
|
||||
|
||||
parser_download = subparsers.add_parser("download",
|
||||
help="Download a snap from the store.")
|
||||
parser_download.set_defaults(func=self._download)
|
||||
|
||||
parser_info = subparsers.add_parser("info",
|
||||
help="Retrieve information about a snap.")
|
||||
parser_info.set_defaults(func=self._info)
|
||||
|
||||
# Add common parameters.
|
||||
for parser in [parser_download, parser_info]:
|
||||
parser.add_argument("--cohort-key", dest="cohort_key",
|
||||
help="A cohort key to pin the channel map to.", type=str)
|
||||
parser.add_argument("--channel", dest="channel",
|
||||
help="The publication channel to query (default: stable).",
|
||||
type=str, default="stable")
|
||||
parser.add_argument("--series", dest="series",
|
||||
help="The device series (default: 16)",
|
||||
type=int, default=16)
|
||||
parser.add_argument("--arch", dest="arch",
|
||||
help="The Debian architecture (default: amd64).",
|
||||
type=str, default=self._get_host_deb_arch())
|
||||
parser.add_argument("snap", help="The name of the snap.")
|
||||
|
||||
if not args:
|
||||
main_parser.print_help()
|
||||
sys.exit(EXIT_ERR)
|
||||
|
||||
return main_parser.parse_args(args)
|
||||
|
||||
def _cohort_create(self, _, **kwargs):
|
||||
print(Snap.cohort_create())
|
||||
|
||||
def _download(self, snap_name, **kwargs):
|
||||
Snap(snap_name, **kwargs).download()
|
||||
|
||||
def _info(self, snap_name, **kwargs):
|
||||
snap = Snap(snap_name, **kwargs)
|
||||
info = snap.get_details()
|
||||
|
||||
print(dedent("""\
|
||||
name: {}
|
||||
summary: {}
|
||||
arch: {}
|
||||
base: {}
|
||||
channel: {}
|
||||
publisher: {}
|
||||
license: {}
|
||||
snap-id: {}
|
||||
revision: {}"""
|
||||
.format(
|
||||
snap_name,
|
||||
info.get("summary", ""),
|
||||
snap._arch,
|
||||
info.get("base"),
|
||||
snap._channel,
|
||||
info.get("publisher", {}).get("display-name", ""),
|
||||
info.get("license", ""),
|
||||
info.get("snap-id", ""),
|
||||
info.get("revision", "")
|
||||
))
|
||||
)
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
try:
|
||||
rval = SnapCli()(sys.argv[1:])
|
||||
except KeyboardInterrupt:
|
||||
sys.stderr.write("snap-tool: caught keyboard interrupt, exiting.\n")
|
||||
sys.exit(EXIT_ERR)
|
||||
sys.exit(rval)
|
||||
Loading…
Reference in new issue