mirror of
https://github.com/Telecominfraproject/OpenNetworkLinux.git
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a4cefaf8f5
python3 is starting to become the default on all major distributions. Using `/usr/bin/python2` should be safe for the near future.
148 lines
4.0 KiB
Python
Executable File
148 lines
4.0 KiB
Python
Executable File
#!/usr/bin/python2
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############################################################
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#
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# Extended YAML Support
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#
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# Supports include files and variable interpolations.
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#
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############################################################
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import yaml
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import os
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import pprint
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import tempfile
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from string import Template
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class OnlYamlError(Exception):
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"""General Error Exception"""
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def __init__(self, value):
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self.value = value
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def __str__(self):
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return self.value
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def dflatten(rv, in_):
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if type(in_) is dict:
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rv.update(in_)
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return rv
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elif type(in_) is list:
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for e in in_:
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dflatten(rv, e)
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return rv
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else:
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raise OnlYamlError("Element type '%s' cannot be added to the given dictionary." % (type(in_)))
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def loadf(fname, vard={}):
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# Apply variable interpolation:
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def interpolate(s, d):
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error_string = "Yaml variable substitution error: '%s' could not be resolved."
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try:
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template = Template(s)
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s = template.substitute(d)
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except KeyError as e:
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raise OnlYamlError(error_string % (e.args[0]))
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except:
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raise
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return s
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variables = {}
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# Files can reference environment variables
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variables.update(os.environ)
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# Files can reference their own directory.
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variables['__DIR__'] = os.path.dirname(os.path.abspath(fname))
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# Files can reference invokation parameters.
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variables.update(vard)
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# Yaml Include constructor. Allows variables.
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def onlyaml_include(loader, node):
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# Get the path out of the yaml file
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directive = node.value
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fields = directive.split()
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fname = fields[0]
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options = fields[1:]
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for opt in options:
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try:
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(k,v) = opt.split('=')
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except ValueError:
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raise OnlYamlError("Bad include directive: %s" % opt)
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variables[k] = v;
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fname = interpolate(fname, variables)
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if not os.path.isabs(fname):
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fname = os.path.join(os.path.dirname(loader.name), fname)
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if not os.path.exists(fname):
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raise OnlYamlError("Include file '%s' (from %s) does not exist." % (fname, loader.name))
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return loadf(fname, variables)
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# Yaml dynamic constructor. Allow dynamically generated yaml.
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def onlyaml_script(loader, node):
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directive = interpolate(node.value, variables)
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tf = tempfile.NamedTemporaryFile()
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tf.close()
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if os.system("%s > %s" % (directive, tf.name)) != 0:
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raise OnlYamlError("Script execution '%s' failed." % directive)
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return loadf(tf.name, variables)
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yaml.add_constructor("!include", onlyaml_include)
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yaml.add_constructor("!script", onlyaml_script)
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# First load: grab the variables dict
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string = open(fname).read()
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try:
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data = yaml.load(string)
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except Exception, e:
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raise OnlYamlError("%s\n(filename: %s)" % (e, fname))
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if type(data) is dict:
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_v = dflatten({}, data.get('variables', {}))
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variables.update(_v)
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for (k,v) in _v.iteritems():
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k = interpolate(k, variables)
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v = interpolate(v, variables)
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variables[k] = v
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############################################################
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#
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# Interpolate the entire package contents using the
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# generated variables dict and reload it.
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#
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############################################################
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string = interpolate(string, variables)
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try:
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data = yaml.load(string)
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except OnlYamlError, e:
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raise e
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except Exception, e:
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raise OnlYamlError("Interpolation produced invalid results:\n%s\n" % string)
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return data
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if __name__ == '__main__':
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import sys
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try:
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if len(sys.argv) == 2:
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print yaml.dump(loadf(sys.argv[1]))
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else:
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sys.stderr.write("usage: %s <yamlfile>\n" % sys.argv[0])
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except OnlYamlError, e:
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sys.stderr.write("error: %s\n" % e.value)
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