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Created September 10, 2014 15:34
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Amazon ID plugin for YUM. This will add 2 headers to the HTTP requests. With these headers the YUM repo server can identify the EC2 instance. These files come from the rh-amazon-rhui-client RPM package found on RHEL EC2 instances, probably part of the Red Hat Update Infrastructure (https://access.redhat.com/products/red-hat-update-infrastructure/)…
[main]
enabled=1
#!/usr/bin/python
#
# Copyright (c) 2010 Red Hat, Inc.
#
# This software is licensed to you under the GNU General Public License,
# version 2 (GPLv2). There is NO WARRANTY for this software, express or
# implied, including the implied warranties of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. You should have received a copy of GPLv2
# along with this software; if not, see
# http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
#
# Red Hat trademarks are not licensed under GPLv2. No permission is
# granted to use or replicate Red Hat trademarks that are incorporated
# in this software or its documentation.
import base64
import urllib2
try:
import simplejson as json
except:
import json
from urllib2 import ProxyHandler
from yum.plugins import TYPE_CORE
requires_api_version = '2.3'
plugin_type = (TYPE_CORE,)
ID_DOC_HEADER = "X-RHUI-ID"
ID_SIG_HEADER = "X-RHUI-SIGNATURE"
ID_DOC_URL = "http://169.254.169.254/latest/dynamic/instance-identity/document"
ID_SIG_URL = "http://169.254.169.254/latest/dynamic/instance-identity/signature"
# Instance from one region will be redirected to another region's CDS for content
REDIRECTS = [('us-gov-west-1', 'us-west-2')]
# We do not want to use a proxy to read the Amazon instance metadata, so bypass
# any proxy that might be set, including by http{s}_proxy environment
# variable(s).
proxy_handler = ProxyHandler({})
opener = urllib2.build_opener(proxy_handler)
def init_hook(conduit):
'''
Plugin initialization hook. For each RHUI repo, replace yum's representation of the
repo with a subclass that adds in the necessary headers.
'''
# Only process RHUI repos
repos = conduit.getRepos()
rhui_repos = repos.findRepos('rhui-*')
# Retrieve the Amazon metadata
id_doc = _load_id()
id_sig = _load_signature()
if id_doc and id_sig:
# Encode it so it can be inserted as an HTTP header
# Signature does not need to be encoded, it already is.
id_doc = base64.urlsafe_b64encode(id_doc)
id_sig = base64.urlsafe_b64encode(id_sig)
# Add the headers to all RHUI repos
for repo in rhui_repos:
repo.http_headers[ID_DOC_HEADER] = id_doc
repo.http_headers[ID_SIG_HEADER] = id_sig
def prereposetup_hook(conduit):
# Dynamically set the mirrorlist to the appropriate region
# bz#921116, copy ami to another region
# Setting repo.mirrorlist causes traceback, setting repo.url instead
# Only process RHUI repos
repos = conduit.getRepos()
rhui_repos = repos.findRepos('rhui-*')
for repo in rhui_repos:
original = repo.mirrorlist
try:
region_new = json.loads(_load_id())["region"]
# Check if redirect is necessary
for reg, redirect in REDIRECTS:
if reg == region_new.strip():
region_new = redirect
start = original.find(".") + 1
end = original.find(".", start)
region_old = original[start:end]
if region_new != region_old:
repo.mirrorlist = original.replace(region_old, region_new).encode('ascii')
conduit.info(5, "mirrorlist: %s" % str(repo.mirrorlist))
except:
# We failed to get region name from EC2
conduit.error(0, "Failed to get region name from EC2")
def _load_id():
'''
Loads and returns the Amazon metadata for identifying the instance.
@rtype: string
'''
try:
fp = opener.open(ID_DOC_URL)
id_doc = fp.read()
fp.close()
except urllib2.URLError:
return None
return id_doc
def _load_signature():
'''
Loads and returns the signature of hte Amazon identification metadata.
@rtype: string
'''
try:
fp = opener.open(ID_SIG_URL)
id_sig = fp.read()
fp.close()
except urllib2.URLError:
return None
return id_sig
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