init

init.sh is an automated configurator for system administrator. It’s fully written using Bash scripting and aims to be platform independent. Nevertheless, it’s requirements turns it naturally to Linux systems. It have long been tested using Debian GNU/Linux, Devuan and different flavor of Ubuntu.

Getting started

You should consider reading that document entirely before use. If you need to create additional modules to meet your needs, consider reading the Developer’s guide.

Please also consider that your needs might meet the needs of someone else, thus it would be a good idea to submit your module to init.sh source base.

Design

init.sh relies on three different elements to work:

  • the init.sh script, which provide a simple framework and libraries to do simple taks and embed system dependent functions to provide system independent function calls.
  • modules that actually do the job, as possible on a system independant way through the use of the framework and consisting on very small and simple tasks.
  • multilevel configuration files, being simply Bash variables declaration.

Additionally some module might be ran regularly so it could be integrated in a cron-like service.

Command line

The init.sh script allows some command line parameters and some environement variables to change it’s behaviour.

The parameters are:

  • -m <list>, –module <list>: Allows to manually give a module list and overide the MODULE_LIST variable declaration. The list is a comma separated module name. If that option is provided, the module list is mandatory.
  • -c, –check-only: Do not launch any actions, only the checks are launched. In that situation, no change should be done to the system.
  • -j, –jump: Jump the checks and goes directly to system transformation. That option should only be run after successfull checks (eg. after using the –checkonly option).
  • -k, –keep-going: The scripts will try to continue even if errors occurs. Thus some unrecoverable errors might stop the script anyway if it not allowing it to work. Please use with care as it might leads to unexpected results.
  • -r, –resume: Restart an interrupted process with the last executed module that failed.
  • -R, –no-root-check: Désactive la vérification des droits root (ou UID 0).
  • -h, –help: Affiche des informations sur l’usage de la ligne de commande.
  • -l, –logfile: Specify a custom name for the logfile. Standard logfile is named init-hostname-date-time.log in the log subdirectory. That file can also be customized using the LOGFILE environement variable.
  • -v, –version: Display version information, including available module list and their version.

Loading order and process

The first thing the script do is loading its libraries contained in the “lib” directory. Any file situated in that directory ending with the .sh extention will be loaded in alphabetical order. For that reason, error management functions are placed in a file called aaa_error.sh, so it can be loaded first and catch errors that could occurs while loading library files. In the opposite the zzz_main_fct.sh file have to be loaded last, because it’s widely using previously declared libraries.

After that a basic command line parameter treatment is done. That allows the use of –version and –help options in user space. Those options just display informations and don’t require any superuser rights and exit at that point of execution. Everything after that will require administrator rights and the script will exit with error at that point if not superuser.

Next will be the log file creation and the loading of configuration files. At this point a deeper analysis of command line option will be done, triggering errors in case of unconsistency or incompatible options.

Finally checking processes are launched in their declaration order (cf. configuration file). If no error occurs and after a confirmation prompt, final treatment processes, those that actually makes changes, are launched.

Without the –keep-going option any error will imediatelly stop execution. Some errors that could make the script impossible to execute will stop execution, even if the –keep-going option is provided.

Main configuration file

The main configuration file can be two different file. Either it’s completely generic and will be named init.conf.sh in the “conf” directory, either it will be named after the current hostname of the computer in that same “conf” directory. Please remember that the actual name will be used until the end of the execution of init.sh. If one of your module change the hostname, the new name can only be took into account after a new execution of init.sh.

Most of the variable you can declare to configure your host depends on the module you will use. Please refer to module header to see what’s available for your use case.

After a module version upgrade you should check again headers as variable name or stucture might change. A variable ca also be deleted, new variables could appears, and so on.

It is heavily recommended to use includes technique to shorten your configuration file and make a file for your organisation and an other one for the Linux distribution you use. Remember that the declaration order matters, so you can declare something on your organisation configuration file and superseed it in your host configuration file. The only limit will be Bash capabilities in terms of variable manipulation.

Naming conventions

Because of internal mechanics the dash character is forbidden in module names. Thus Bash language also forbid that character in variable name.

An other limit is, even if digits are allowed in module names and variable, they can’t be used as a leading character or worse the full name being only made of digits. You can use as many digits you want in names but with at least a leading alphabetical (or underscore) character, whatever the case of that character will be.

You can use upper case and lower case as you wish, with underscore character, even as leading character. Any other special character than alphanumerical or underscore is completely forbidden.

Any submitted module to the central repository will have module name in lower case with underscore to separate words and ease reading, and variable name upper case with the same underscore as word separator.

Basic module structure

Please note that modules are not supposed to contain any specific code for a platform or a distribution even if nothing block you doing so. It is highly recommended to use configurations files to introduce any platform dependent code. Additionally, it will be possible to create system dependent modules using naming convention in the style module_name.debian.x86_64.sh (awaited for version 2 of init.sh).

In the following exemple @template@ have to be replaced with the name of your module with the filename @template@.sh. You can automatically create your new module with the following command:

sed -e “s/@template@/module_name/g” -e “/^# .*/d” -e “s/^##/# /” template > \

module_name.sh

Versionning modules is up to you but the recommended behavior follows somme standard rules. Considering a numbering as x.y.z:

  • x might be incremented in case of major change, rewriting or deferent approach on the way to have the job done, used variable could massively change ;
  • y might be incremented in case simple functionnality addition or basic improvements, existing variable might not change but new ones could appears ;
  • z might be incremented only when correcting problems and/or bugs (+n fix => +n to increment), variable should not change.

Unless only configuration files have been changed, any change in the code implies an increment of a version number in the code and a git commit.

# Description @template@ module

# Module version

export VER_@template@=”0.0.1″

# Module main code

@template@()

{

# Code

}

# Pre-run checks code

precheck_@template@()

{

# Code

}

# Any public fonction have to be exported

export -f @template@

export -f precheck_@template@

Error code table

The following table is giving a list of error code with explanation:

Code

Meaning

0

No error

1

Command line syntax error

2

Unable to find configuration

3

Missing library file or function

4

No root rights

5

Malformed module list

10

Function call error

11

Bad function call

12

Error copying files

13

Bad target filesystem

50..100

Error in module execution

128

Abortion due to external cause

150..200

Error in module checks

Contact and more information

Everything except configuration files are licensed under BSD-3 license. Please check licence file.

You can mail author to fatalerrors <at> geoffray-levasseur <dot> org

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