193 lines
		
	
	
		
			7.4 KiB
		
	
	
	
		
			Python
		
	
	
		
			Executable File
		
	
	
	
	
			
		
		
	
	
			193 lines
		
	
	
		
			7.4 KiB
		
	
	
	
		
			Python
		
	
	
		
			Executable File
		
	
	
	
	
#!/usr/bin/env python3
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# Copyright 2019 The Kubernetes Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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#     http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import json
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import re
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import requests
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import sys
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import tarfile
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from io import BytesIO
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KUBE_SRC = "https://dl.k8s.io"
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KUBE_RESOLVED_SEM = "kubernetes_semver"
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KUBE_RESOLVED_SRC = "kubernetes_http_source"
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KUBE_RESOLVED_VER = "kubernetes_version"
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# KubeVersionResolver is used for resolving Kubernetes version strings to the
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# actual version and URL or package string that may be used to deploy
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# Kubernetes.
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class KubeVersionResolver(object):
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    # Resolve accepts a Kubernetes version string and returns a dictionary with
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    # information that can be used to deploy the provided version.
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    def Resolve(self, version):
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        if version == '':
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            raise Exception('version is required')
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        result = {
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            KUBE_RESOLVED_SEM: version,
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            KUBE_RESOLVED_SRC: 'pkg',
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            KUBE_RESOLVED_VER: version,
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        }
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        # When version is 'latest' then the returned dictionary points
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        # to the latest package for Kubernetes.
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        if version == 'latest':
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            return result
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        # Otherwise check to see if the provided version matches a
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        # managed package format. Technically the else clause could be
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        # descoped one level, but by placing the logic in the scope of
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        # the else clause, the scope of 'match' is isolated from the
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        # rest of this function.
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        else:
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            match = re.match(r'^(\d+\.\d+.\d+)\-\d+$', version)
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            if match:
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                version = match.groups(1)[0]
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                result[KUBE_RESOLVED_SEM] = f'v{version}'
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                return result
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        url = ''
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        if re.match(r'(?i)^https?:', version):
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            url = version
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        elif re.match(r'^v?\d+(?:\.\d+){0,3}(?:[.+-].+)?$', version):
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            if not version.startswith('v'):
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                version = f'v{version}'
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            url = f'{KUBE_SRC}/release/{version}'
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        elif re.match(r'^(ci|release)/.+$', version):
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            url = self.__resolve_build_url(version)
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        else:
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            raise Exception(f'Invalid Kubernetes version: {version}')
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        result[KUBE_RESOLVED_SRC] = url
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        version = self.__read_version_from_kube_tarball(url)
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        result[KUBE_RESOLVED_SEM] = version
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        result[KUBE_RESOLVED_VER] = version
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        return result
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    def __resolve_build_url(self, buildID):
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        url = f'{KUBE_SRC}/{buildID}'
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        # If the URL doesn't end with '.txt' then see if the URL is already valid.
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        if not url.endswith('.txt'):
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            # If there is a kubernetes tarball available at the root of the URL
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            # then it is already a valid URL.
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            try:
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                r = requests.head(url, allow_redirects=True)
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                if r.status_code >= 200 and r.status_code <= 299:
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                    return url
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            except:
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                pass
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            # The URL wasn't valid, so add '.txt' to the end and let's see if the
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            # URL points to a valid build.
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            url = f'{url}.txt'
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        # Do an HTTP GET on the txt file to get the actual Kubernetes version.
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        version = requests.get(url).text
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        version = version.strip()
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        if buildID.startswith('ci/'):
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            version = f'ci/{version}'
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        url = f'{KUBE_SRC}/{version}'
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        return url
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    def __read_version_from_kube_tarball(self, url):
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        url = f'{url}/kubernetes.tar.gz'
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        r = requests.get(url)
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        if not r.status_code == 200:
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            raise Exception(f'HTTP GET {url} failed: {r.status_code}')
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        b = BytesIO(r.content)
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        t = tarfile.open(fileobj=b, mode='r')
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        v = t.extractfile('kubernetes/version')
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        return v.read().strip().decode('utf-8')
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if __name__ == '__main__':
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    import argparse
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    import textwrap
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    parser = argparse.ArgumentParser(
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        formatter_class=argparse.RawTextHelpFormatter,
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        description='Generates new Kubernetes image config',
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        epilog=textwrap.dedent(r'''
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            THE VERSION STRING
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            ====================================================================
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            The version string not only determines what version of Kubernetes 
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            will be installed, but also *how* Kubernetes is installed.
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            PLACEHOLDERS
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            ====================================================================
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            The following placeholders are used in the examples below:
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            BASE_URI  https://dl.k8s.io
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            K8S_TGZ   kubernetes.tar.gz
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            PACKAGE MANAGER INSTALLATION
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            ====================================================================
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            If the version string matches the pattern "^\d+\.\d+.\d+\-\d+$",
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            ex. 1.14.0-0, then Kubernetes is installed using the system's
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            package manager, such as yum or apt.
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            MANUAL INSTALLATION
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            ====================================================================
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            If the string does not match the above pattern then the following
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            logic is used to resolve the string VALUE to a valid Kubernetes
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            version along with the URLs for the Kubernetes artifiacts required
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            for installation:
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              1. If the VALUE begins with "http:" or "https:" then the value is
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              treated as a URL and the Kubernetes version is obtained by reading
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              the "kuberentes/version" file from the URL "VALUE/K8S_TGZ".
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              2. If the VALUE matches a semantic version then the value is
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              treated as a release build and "BASE_URI/release/SEMVER"
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              is processed like the URL in step one.
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              3. If the VALUE begins with "ci/" then:
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                a. If VALUE does not end with ".txt" then a HEAD request is used
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                to check the existence of "BASE_URI/VALUE/K8S_TGZ":
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                  i. If the HEAD request is successful then the URL is processed
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                  like the one in step one.
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                  ii. If the HEAD request fails then ".txt" is added to the end
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                  of the URL and is processed by step 3b.
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                b. If VALUE *does* end with ".txt" then a GET request is used to
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                read "BASE_URI/VALUE" in order to get the dereferenced
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                version string. Then "BASE_URI/ci/DEREF" is processed
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                like the URL in step one.
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              4. If the VALUE begins with "release/" then the VALUE is processed
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              like step three, without the "ci/" prefix
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            The resolved URL is used to install Kuberentes from the set of
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            pre-built container images and binaries.
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    '''))
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    parser.add_argument('version',
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                        nargs=1,
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                        help='A Kubernetes version string')
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    args = parser.parse_args()
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    resolver = KubeVersionResolver()
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    result = resolver.Resolve(args.version[0])
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    data = json.dumps(result, indent=2)
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    print(data)
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