Ansible源码解析Inventory动态inventory脚本解析script.py
class InventoryScript(object): ''' Host inventory parser for ansible using external inventory scripts. '''def __init__(self, filename=C.DEFAULT_HOST_LIST):
# Support inventory scripts that are not prefixed with some
# path information but happen to be in the current working
# directory when '.' is not in PATH.
# 获取绝对路径
self.filename = os.path.abspath(filename)
# 参数
cmd = [ self.filename, "--list" ]
try:
# 尝试调用调用出错或是返回码不为0的话就直接报错
sp = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
except OSError, e:
raise errors.AnsibleError("problem running %s (%s)" % (' '.join(cmd), e))
(stdout, stderr) = sp.communicate()
if sp.returncode != 0:
raise errors.AnsibleError("Inventory script (%s) had an execution error: %s " % (filename,stderr))
self.data = stdout
# see comment about _meta below
self.host_vars_from_top = None
self.groups = self._parse(stderr)
# 这个方法是核心
def _parse(self, err):
all_hosts = {}
# not passing from_remote because data from CMDB is trusted
# 通过json解析， json_dict_bytes_to_unicode
self.raw= utils.parse_json(self.data)
# 递归解析字典、列表、元组去一个字符串，这是一个内置的方法
self.raw= json_dict_bytes_to_unicode(self.raw)
# 和group类处理的相同
all = Group('all')
groups = dict(all=all)
group = None
# 有错误输出
if 'failed' in self.raw:
sys.stderr.write(err + "\n")
raise errors.AnsibleError("failed to parse executable inventory script results: %s" % self.raw)
# 获取组信息
for (group_name, data) in self.raw.items():
# in Ansible 1.3 and later, a "_meta" subelement may contain
# a variable "hostvars" which contains a hash for each host
# if this "hostvars" exists at all then do not call --host for each
# host.This is for efficiency and scripts should still return data
# if called with --host for backwards compat with 1.2 and earlier.
# 这个_meta一般为主机设置环境变量，即可以不通过--host再去获取主机的相应信息
# 这个方法主要是为了省带宽
if group_name == '_meta':
if 'hostvars' in data:
# 设置这完意，然后就进行下一次循环
self.host_vars_from_top = data['hostvars']
continue
# 组名不是all 就实例一个group
if group_name != all.name:
group = groups = Group(group_name)
else:
group = all
host = None
# data不是字典直接赋值
if not isinstance(data, dict):
data = {'hosts': data}
# is not those subkeys, then simplified syntax, host with vars
# 看过group的很好理解
elif not any(k in data for k in ('hosts','vars','children')):
data = {'hosts': , 'vars': data}
# hosts在组里面，并且不是列表就报错，不然就添加主机进这个组
if 'hosts' in data:
if not isinstance(data['hosts'], list):
raise errors.AnsibleError("You defined a group \"%s\" with bad "
"data for the host list:\n %s" % (group_name, data))
# 添加主机进这个组
for hostname in data['hosts']:
if not hostname in all_hosts:
all_hosts = Host(hostname)
host = all_hosts
group.add_host(host)
# 设置组的环境变量，同样做个异常判断不是字段就报错
# 同上因为主机是列表，而变量是key/value形式
if 'vars' in data:
if not isinstance(data['vars'], dict):
raise errors.AnsibleError("You defined a group \"%s\" with bad "
"data for variables:\n %s" % (group_name, data))
for k, v in data['vars'].iteritems():
if group.name == all.name:
all.set_variable(k, v)
else:
group.set_variable(k, v)
# Separate loop to ensure all groups are defined
# 添加子组
for (group_name, data) in self.raw.items():
if group_name == '_meta':
continue
if isinstance(data, dict) and 'children' in data:
for child_name in data['children']:
if child_name in groups:
groups.add_child_group(groups)
# 这里搞定all组
for group in groups.values():
if group.depth == 0 and group.name != 'all':
all.add_child_group(group)
return groups
# 这里就是--host的处理了
def get_host_variables(self, host):
""" Runs <script> --host <hostname> to determine additional host variables """
# 就是前面的"_meta"的东西， 通过主机参数获取他的相应的变量字典
if self.host_vars_from_top is not None:
got = self.host_vars_from_top.get(host.name, {})
return got
# 直接跑
cmd =
try:
sp = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
except OSError, e:
raise errors.AnsibleError("problem running %s (%s)" % (' '.join(cmd), e))
(out, err) = sp.communicate()
if out.strip() == '':
return dict()
try:
return json_dict_bytes_to_unicode(utils.parse_json(out))
except ValueError:
raise errors.AnsibleError("could not parse post variable response: %s, %s" % (cmd, out))
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