dasscm

dass configuration managment (dasscm) is a simple solution for managing system configuration file with Subversion. It is favored because of its easy setup and low footsprint. It can be easily integrated into Nagios monitoring.

Features

• version file directly on the target system. Keeping track of the Subversion checkout is done automatically in the background
• work with your system id, but checkin files with your Subversion id
• easy status check (are all file checked in?). Can be easily integrated into Nagios

• dasscm

Installation Repositories

package repositories (RPM and DEB)	​http://download.opensuse.org/repositories/home:/dassit/
source code	source:dasscm/trunk​

Wording

It is not always easy to get the context of eg. repository, because it can mean "server side svn repository", "package repository", like "RPM repository" or sometimes also your local svn ckeckout. To distinguish between the different terms, we try to use the following terms in a consistent way:

target system	the system were dasscm is installed and used
Subverson server	the system were your SVN repository is hosted
system files	config and other files on your system, like /etc/ntp.conf
system files managed by dasscm	the part of your system files that has already been checked in to Subversion via dasscm
local svn checkout	your local svn checkout on the target system
svn repository	the Subversion repository were the "system files managed by dasscm" are versioned
package repository	the installation source repository for dasscm

About

dasscm is a wrapper Perl script around the svn command. If you're planing to check-in your system configuration files into a Subversion repository, dasscm eases your life.

Instead of copying files from the system to the corresponding local subversion checkout directory and commit them there, you just use:

dasscm login
dasscm add /etc/ntp.conf

Missing directories are added automatically.

But the real advantage, compared to plain svn is, that there is the possibility to check, if your local system files have changed against the repository. Just call:

dasscm status

For Nagios NRPE integration use

dasscm check

Pre-Requirements

• an existing empty directory in a subversion repository. Normally you create a new directory of every dasscm installation (like ​http://mysubversionserver/config/HOSTNAME)
• a user with read permissions to this subversion repository. The username dasscm is a good choice

Configuration

After installing it is required to configure dasscm. All configuration changes have to be done in the file /etc/dasscm.conf

Include(source:dasscm/trunk/dasscm.conf, text/plain)

Set the following variables according to your needs:

DASSCM_REPOSITORY_NAME=system-name	normally hostname -f
DASSCM_CHECKOUT_USERNAME=dasscm	subversion user with read-only permissions
DASSCM_CHECKOUT_PASSWORD=dasscm-password	subversion password for $DASSCM_CHECKOUT_USERNAME
DASSCM_SVN_REPOSITORY_BASE=http://your-svn-repository/path/	subversion directory in which the $DASSCM_REPOSITORY_NAME directory is located

If it not already exists, you can create your subversion subdirectory by

source /etc/dasscm.conf
svn mkdir -m "initial" --no-auth-cache $DASSCM_SVN_REPOSITORY_BASE/$DASSCM_REPOSITORY_NAME

Subcommands

dasscm suppots following subcommands:

help
init
login <username>
up <path>
ls <path>
add <path>
commit <path>
revert <path>
diff <path>
status <path>
check
cleanup
permissions

login

For convinience use

dasscm login

This opens a shell, where the environment is set to the required values.

add files/directories

For example cups configuration

# it is recommended to check initially check a file before you first edit it. Use the comment "orig"
dasscm add -m "orig" /etc/sysconfig/cups
# make you changes to /etc/sysconfig/cups
dasscm commit -m "my comment about my change" /etc/sysconfig/cups

checkin modified files

dasscm commit -m "my comment about my change" /etc/sysconfig/cups

Note: every "add" also calls "commit", so the command "commit" is not really required

status

dasscm status

store file permissions

on every call of dasscm add/commit als file permissions are evaluated and stored in the file

/etc/permissions.d/dasscm.permissions_backup

restore file permissions

On SUSE system:

cp -a /etc/permissions.d/dasscm.permissions_backup /etc/permissions.d/dasscm.permissions
# change all file permissions to the values, that are defined in the file /etc/permissions.d/*.permissions
/sbin/conf.d/SuSEconfig.permissions

diff

dasscm diff $filename

shows the differences of a local system file against the file in the local svn checkout.

revert

If a local system file is modified (see dasscm diff) it can be reverted to the checked in version by

dasscm revert $filename

help

for online-help type

dasscm help

dasscm as non-root user

Using dasscm as non-root user requires sufficient permissions.

• create group dasscm. Default GID is 4199
• chgrp dasscm /etc/dasscm.conf
• verify group dasscm has read permission on /etc/dasscm.conf

why sudo?

sudo is required to gurantie that the user has access to all files on the target system.

configure dasscm for non-root users

# check if group dasscm is defined (GID 4199 is default)
# The group must contain all users that should use dasscm
getent group dasscm

# read permission on config file
chgrp dasscm /etc/dasscm.conf

# add sudo rule
echo "
Defaults env_keep+=DASSCM_USERNAME
Defaults env_keep+=DASSCM_PASSWORD
dasscm ALL=(ALL) NOPASSWD:/usr/bin/dasscm" >> /etc/sudoers

Also check, that requiretty is disabled. On SUSE, this is the default, on RedHat it requires modifying the /etc/sudoers.

usage (non-root)

# login
dasscm login

sudo dasscm status

sudo dasscm ls

sudo dasscm add <DATEINAME>

Nagios/NRPE Check

Client-side configuration for NRPE

# nrpe config file
CFG=/etc/nagios/nrpe.cfg

# get NRPE user
NRPE_USER=`sed -n 's/nrpe_user=//p' $CFG`
echo "NRPE_USER: $NRPE_USER"


# add NRPE_USER sudo rule for dasscm
grep -q "dasscm check" /etc/sudoers || echo "$NRPE_USER ALL=(ALL) NOPASSWD:/usr/bin/dasscm check" >> /etc/sudoers

# add check_dasscm to NRPE config
grep -q dasscm $CFG || echo "command[check_dasscm]=sudo dasscm check" >> $CFG

# restart nrpe
/etc/init.d/nrpe restart

It is possible to user the dasscm nrpe check without sudo, that file without read-permissions will not be checked

addititional info

from dasscm/trunk/doc/dasscm_howto.txt​: Include(source:dasscm/trunk/doc/dasscm_howto.txt, text/plain)

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