YAIM in EMI Functional Description

Introduction

YAIM (Yet Another Installation Method) is a software to configure grid services. The aim of YAIM is to provide simple configuration methods that can be used to set up uniform grid sites but can also be adapted and extended to meet the needs of larger sites. To ensure that local administrators can adapt YAIM, it has been implemented as a set of bash scripts. To support the component based release model within the EGEE project, YAIM has been modularized and a YAIM core is supplemented by component specific scripts distributed as RPMs.

YAIM directory structure

When a YAIM module is installed, the following directory structure is created under /opt/glite/yaim: • node-info.d contains a set of files per node type with the format name glite-node_type. These files contain a list of functions to configure the corresponding node type. • functions contains the functions that configure each node type. They are all bash scripts. They have the format configure_function_name. • functions/local contains functions defined by the site administrators. These functions can override the ones provided by YAIM if the same function name is used. • defaults contains .pre and .post files to be sourced before and after the files that contain the configuration variables. • bin contains the main yaim executable. • log contains the yaim log file called yaimlog. • examples contains examples of configuration files and other files like users.conf and groups.conf needed in the configuration of the node types.

Configuration flow in YAIM

When configuring a node type, the different configuration files are sourced in a specific order. In the following example we are configuring a node type called LFC, in the host lxb001.cern.ch and using the VO atlas. Our siteinfo folder is under /root/siteinfo:

1. /opt/glite/yaim/defaults/site-info.pre
2. /opt/glite/yaim/defaults/glite-lfc.pre
3. /root/siteinfo/site-info.def
4. /root/siteinfo/services/glite-lfc
5. /opt/glite/yaim/defaults/site-info.post
6. /opt/glite/yaim/defaults/glite-lfc.post
7. /root/siteinfo/nodes/lxb001.cern.ch
8. /root/siteinfo/vo.d/atlas
9. /opt/glite/yaim/node-info.d/glite-lfc

Files in red are provided by the yaim core module. Files in blue are provided by the yaim lfc module. All of them are mandatory. The remaining files are optional and can be added by the system administrator. Moreover, the system administrator can also put /root/siteinfo/services/glite-lfc variables in site-info.def to use one central file.

YAIM configuration variables

In the /opt/glite/yaim/examples/siteinfo directory a set of examples for the needed configuration files can be found. This location is world readable and therefore site administrators should find a safer path for the configuration files but always under the same folder. The configuration folder should contain:

• site-info.def: contains a list of configuration variables in the format of key-value pairs. It's a mandatory file and it's a parameter passed to the YAIM command. It can contain a complete list of all the variables needed to configure a site or a minimum set of variables common to all node types.

Optionally, the configuration folder can contain:

• services: contains a file per node type with the format glite-node-type. The file contains a list of configuration variables specific to that node type. It can be used together with the main site-info.def to structure the configuration variables in per node basis.
• nodes: contains a file per host with the format hostname.domain_name. The file contains host specific variables that are different from one host to another in a certain site.
• vo.d: contains a file per VO with the format vo_name.

The optional folders are meant to help system administrators to organise the configuration in a more structured way but it’s up to them to keep the site configuration in site-info.def.

There is also an example of users.conf and groups.conf files under /opt/glite/yaim/examples/. These files can be placed at any location since their path is specified in the variables USERS_CONF and GROUPS_CONF in site-info.def.

How to build your own YAIM module

In order to create your own YAIM module you have to follow these steps:

• create the node type function list under node-info.d/
• define the corresponding functions under functions/
• define node type specific configuration files under services/

YAIM command

Usage: /opt/glite/yaim/bin/yaim <action> <parameters>
Actions:
-c | --configure    : Configure already installed services.
                             Compulsory parameters: -s, -n
-r | --runfunction : Execute a configuration function.
                             Compulsory parameters: -s, -f
                             Optional parameters : -n
-v | --verify          : Checks that the necessary variables
                             are all defined in site-info.def.
                             Compulsory parameters: -s –n
-h | --help            : This is help

Parameters:

-s | --siteinfo         : Location of the site-info.def file
-n | --nodetype     : Name of the node type(s) to configure
-f | --function        : Name of the functions(s) to execute

Examples:

• Configuration:

/opt/glite/yaim/bin/yaim -c -s /root/siteinfo/site-info.def -n SE_dpm_mysql

• Running a function:

/opt/glite/yaim/bin/yaim -r -s /root/siteinfo/site-info.def -n creamCE –f config_users

• Verify your site-info.def:

/opt/glite/yaim/bin/yaim -v -s /root/siteinfo/site-info.def -n SE_storm_backend

References

• YAIM leaflet - https://edms.cern.ch/file/865512/1/YAIMleaflet.pdf