cli_install.py 文件源码

def get_cluster_version(dcos_url):
    """Given a cluster url, return its version string, such as 1.7, 1.8,
    1.8.8, 1.9, 1.9-dev, etc"""
    version_url = "%s/%s" % (dcos_url, "dcos-metadata/dcos-version.json")
    # Since our test clusters have weird certs that won't validate, turn off
    # validation
    try:
        # this will handle a variety of versions, including some 2.7.x
        # (haven't investigated which) and all recent 3.x
        noverify_context = ssl.SSLContext()
    except:
        if hasattr(ssl, 'PROTOCOL_TLS'):
            # 2.7.13
            noverify_context = ssl.SSLContext(ssl.PROTOCOL_TLS)
        elif hasattr(ssl, 'OP_NO_SSLv2'):
            # 2.7.9-2.7.12
            logger.warn("Old python; Asking for something better than sslv2 or 3")
            noverify_context =  ssl.SSLContext(ssl.PROTOCOL_SSLv23)
            # explicitly switch these off.  This is recommended for ancient
            # versions as per https://docs.python.org/2/library/ssl.html#protocol-versions
            noverify_context.options |=  ssl.OP_NO_SSLv2
            noverify_context.options |=  ssl.OP_NO_SSLv3
        else:
            # before 2.7.9
            logger.error("*VERY* old python.  Very weak/unsafe encryption ahoy.")
            noverify_context =  ssl.SSLContext(ssl.PROTOCOL_SSLv23)

    response = urllib.request.urlopen(version_url, context=noverify_context)
    encoding = 'utf-8' # default
    try:
        #python3
        provided_encoding = response.headers.get_content_charset()
        if provided_encoding:
            encoding =  provided_encoding
    except:
        pass
    json_s = response.read().decode(encoding)
    ver_s = json.loads(json_s)['version']
    return ver_s