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Fix multiple issues with alternatives module

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- Changes are no longer erroneously reported on RHEL (#12)
 - Adding new link groups on Debian works again.
   - This was broken in a previous commit by assuming the OS was RHEL
     if `update-alternatives --query <name>` had a return code of 2
 - Prefer `--display` over `--query` for determining available
   alternatives
   - --display is more distro-agnostic and simplifies the code
 - Fix missing `msg=` in `fail_json` call when `link` is missing
 - Document that `link` is required on RHEL-based distros

Tested on Ubuntu 12.04+ and CentOS 6/7
This commit is contained in:
David Wittman 2015-03-13 21:09:33 -05:00
parent 696bc60caa
commit 34e7d9c938
1 changed files with 43 additions and 62 deletions
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105
system/alternatives.py
View file

@ -4,6 +4,7 @@
"""
Ansible module to manage symbolic link alternatives.
(c) 2014, Gabe Mulley <gabe.mulley@gmail.com>
(c) 2015, David Wittman <dwittman@gmail.com>
This file is part of Ansible
@ -26,7 +27,7 @@ DOCUMENTATION = '''
module: alternatives
short_description: Manages alternative programs for common commands
description:
- Manages symbolic links using the 'update-alternatives' tool provided on debian-like systems.
- Manages symbolic links using the 'update-alternatives' tool
- Useful when multiple programs are installed but provide similar functionality (e.g. different editors).
version_added: "1.6"
options:
@ -41,6 +42,7 @@ options:
link:
description:
- The path to the symbolic link that should point to the real executable.
- This option is required on RHEL-based distributions
required: false
requirements: [ update-alternatives ]
'''
@ -55,12 +57,14 @@ EXAMPLES = '''
DEFAULT_LINK_PRIORITY = 50
import re
def main():
module = AnsibleModule(
argument_spec = dict(
name = dict(required=True),
path = dict(required=True),
path = dict(required=True),
link = dict(required=False),
),
supports_check_mode=True,
@ -71,78 +75,55 @@ def main():
path = params['path']
link = params['link']
UPDATE_ALTERNATIVES = module.get_bin_path('update-alternatives',True)
UPDATE_ALTERNATIVES = module.get_bin_path('update-alternatives',True)
current_path = None
all_alternatives = []
os_family = None
(rc, query_output, query_error) = module.run_command(
[UPDATE_ALTERNATIVES, '--query', name]
# Run `update-alternatives --display <name>` to find existing alternatives
(rc, display_output, _) = module.run_command(
[UPDATE_ALTERNATIVES, '--display', name]
)
# Gather the current setting and all alternatives from the query output.
# Query output should look something like this on Debian systems:
# Name: java
# Link: /usr/bin/java
# Slaves:
# java.1.gz /usr/share/man/man1/java.1.gz
# Status: manual
# Best: /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java
# Value: /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java
# Alternative: /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java
# Priority: 1061
# Slaves:
# java.1.gz /usr/lib/jvm/java-6-openjdk-amd64/jre/man/man1/java.1.gz
# Alternative: /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java
# Priority: 1071
# Slaves:
# java.1.gz /usr/lib/jvm/java-7-openjdk-amd64/jre/man/man1/java.1.gz
if rc == 0:
os_family = "Debian"
for line in query_output.splitlines():
split_line = line.split(':')
if len(split_line) == 2:
key = split_line[0]
value = split_line[1].strip()
if key == 'Value':
current_path = value
elif key == 'Alternative':
all_alternatives.append(value)
elif key == 'Link' and not link:
link = value
elif rc == 2:
os_family = "RedHat"
# This is the version of update-alternatives that is shipped with
# chkconfig on RedHat-based systems. Try again with the right options.
(rc, query_output, query_error) = module.run_command(
[UPDATE_ALTERNATIVES, '--list']
)
for line in query_output.splitlines():
line_name, line_mode, line_path = line.strip().split("\t")
if line_name != name:
continue
current_path = line_path
break
# Alternatives already exist for this link group
# Parse the output to determine the current path of the symlink and
# available alternatives
current_path_regex = re.compile(r'^\s*link currently points to (.*)$',
re.MULTILINE)
alternative_regex = re.compile(r'^(\/.*)\s-\spriority', re.MULTILINE)
current_path = current_path_regex.search(display_output).group(1)
all_alternatives = alternative_regex.findall(display_output)
if not link:
# Read the current symlink target from `update-alternatives --query`
# in case we need to install the new alternative before setting it.
#
# This is only compatible on Debian-based systems, as the other
# alternatives don't have --query available
rc, query_output, _ = module.run_command(
[UPDATE_ALTERNATIVES, '--query', name]
)
if rc == 0:
for line in query_output.splitlines():
if line.startswith('Link:'):
link = line.split()[1]
break
if current_path != path:
if module.check_mode:
module.exit_json(changed=True, current_path=current_path)
try:
# install the requested path if necessary
# (unsupported on the RedHat version)
if path not in all_alternatives and os_family == "Debian":
if link:
module.run_command(
[UPDATE_ALTERNATIVES, '--install', link, name, path, str(DEFAULT_LINK_PRIORITY)],
check_rc=True
)
else:
module.fail_json("Needed to install the alternative, but unable to do so, as we are missking the link")
if path not in all_alternatives:
if not link:
module.fail_json(msg="Needed to install the alternative, but unable to do so as we are missing the link")
module.run_command(
[UPDATE_ALTERNATIVES, '--install', link, name, path, str(DEFAULT_LINK_PRIORITY)],
check_rc=True
)
# select the requested path
module.run_command(
@ -151,7 +132,7 @@ def main():
)
module.exit_json(changed=True)
except subprocess.CalledProcessError, cpe:
except subprocess.CalledProcessError as cpe:
module.fail_json(msg=str(dir(cpe)))
else:
module.exit_json(changed=False)