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refactor to catch edge cases, remove repeated code

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- Move all the supported YAML file extensions into a constant
- Use helper functions to avoid duplicate code for group/host vars
- Catch and disallow some confusing situations, such as the presence of
  multiple group/host vars files for the same group/host, but with
  different extensions.  For example having both group_vars/all.yml and
  group_vars/all.yaml.
- Catch and report file system permission issues, symlink errors,
  unexpected file system objects
- Trivial performance improvement from making fewer stat system calls
- Restructuring that makes it easy for a following patch to support
  directory recursion
This commit is contained in:
Alan Fairless 2013-10-31 12:05:52 -05:00
parent 4a3e828b83
commit babde9a84c
2 changed files with 99 additions and 36 deletions
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4
lib/ansible/constants.py
View file

@ -89,6 +89,10 @@ if getattr(sys, "real_prefix", None):
else:
DIST_MODULE_PATH = '/usr/share/ansible/'
# check all of these extensions when looking for yaml files for things like
# group variables
YAML_FILENAME_EXTENSIONS = [ "", ".yml", ".yaml" ]
# sections in config file
DEFAULTS='defaults'

131
lib/ansible/inventory/vars_plugins/group_vars.py
View file

@ -16,11 +16,99 @@
# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
import os
import glob
import stat
import errno
from ansible import errors
from ansible import utils
import ansible.constants as C
def _load_vars(basepath, results):
"""
Load variables from any potential yaml filename combinations of basepath,
returning result.
"""
paths_to_check = [ "".join([basepath, ext])
for ext in C.YAML_FILENAME_EXTENSIONS ]
found_paths = []
for path in paths_to_check:
found, results = _load_vars_from_path(path, results)
if found:
found_paths.append(path)
# disallow the potentially confusing situation that there are multiple
# variable files for the same name. For example if both group_vars/all.yml
# and group_vars/all.yaml
if len(found_paths) > 1:
raise errors.AnsibleError("Multiple variable files found. "
"There should only be one. %s" % ( found_paths, ))
return results
def _load_vars_from_path(path, results):
"""
Robustly access the file at path and load variables, carefully reporting
errors in a friendly/informative way.
Return the tuple (found, new_results, )
"""
try:
# in the case of a symbolic link, we want the stat of the link itself,
# not its target
pathstat = os.lstat(path)
except os.error, err:
# most common case is that nothing exists at that path.
if err.errno == errno.ENOENT:
return False, results
# otherwise this is a condition we should report to the user
raise errors.AnsibleError(
"%s is not accessible: %s."
" Please check its permissions." % ( path, err.strerror))
# symbolic link
if stat.S_ISLNK(pathstat.st_mode):
try:
target = os.readlink(path)
except os.error, err2:
raise errors.AnsibleError("The symbolic link at %s "
"is not readable: %s. Please check its permissions."
% (path, err2.strerror, ))
# follow symbolic link chains by recursing, so we repeat the same
# permissions checks above and provide useful errors.
return _load_vars_from_path(target, results)
# directory
if stat.S_ISDIR(pathstat.st_mode):
# we ignore directories. however in the future it may be useful to
# allow variables to be contained in multiple files in the named
# directory, so that users can better organize large variables
# across multiple files.
raise errors.AnsibleError("Expected a variable file at path %s "
"but found a directory instead." % (path, ))
# regular file
elif stat.S_ISREG(pathstat.st_mode):
data = utils.parse_yaml_from_file(path)
if type(data) != dict:
raise errors.AnsibleError(
"%s must be stored as a dictionary/hash" % path)
# combine vars overrides by default but can be configured to do a
# hash merge in settings
results = utils.combine_vars(results, data)
return True, results
# something else? could be a fifo, socket, device, etc.
else:
raise errors.AnsibleError("Expected a variable file but found a "
"non-file object at path %s" % (path, ))
class VarsModule(object):
"""
@ -73,42 +161,13 @@ class VarsModule(object):
continue
# load vars in dir/group_vars/name_of_group
for x in groups:
for group in groups:
base_path = os.path.join(basedir, "group_vars/%s" % group)
results = _load_vars(base_path, results)
p = os.path.join(basedir, "group_vars/%s" % x)
# the file can be <groupname> or end in .yml or .yaml
# currently ALL will be loaded, even if more than one
paths = [p, '.'.join([p, 'yml']), '.'.join([p, 'yaml'])]
for path in paths:
if os.path.exists(path) and not os.path.isdir(path):
data = utils.parse_yaml_from_file(path)
if type(data) != dict:
raise errors.AnsibleError("%s must be stored as a dictionary/hash" % path)
# combine vars overrides by default but can be configured to do a hash
# merge in settings
results = utils.combine_vars(results, data)
# group vars have been loaded
# load vars in inventory_dir/hosts_vars/name_of_host
# these have greater precedence than group variables
p = os.path.join(basedir, "host_vars/%s" % host.name)
# again allow the file to be named filename or end in .yml or .yaml
paths = [p, '.'.join([p, 'yml']), '.'.join([p, 'yaml'])]
for path in paths:
if os.path.exists(path) and not os.path.isdir(path):
data = utils.parse_yaml_from_file(path)
if type(data) != dict:
raise errors.AnsibleError("%s must be stored as a dictionary/hash" % path)
results = utils.combine_vars(results, data)
# same for hostvars in dir/host_vars/name_of_host
base_path = os.path.join(basedir, "host_vars/%s" % host.name)
results = _load_vars(base_path, results)
# all done, results is a dictionary of variables for this particular host.
return results