Service creation

Choose a service name

Guidelines:

Between 8 to 15 characters

Make application code part of the name (first)

Make service type (PRD, DEV) part of the name (second)

Make the last part descriptive of the application role (web, transco)

In case of multiple instance of similar services, happen a number as a suffix

This guidelines result in names like gieprdtransco01, infraprddns01, ...

Following this naming will help grasp importance, clients and role of service from the output of /opt/opensvc/bin/svcmon

Allocate generic account and ip adresses

We recommend to allocate service-dedicated ip addresses, to permit service failover to secondary nodes.

We recommend to allocate service-dedicated generic accounts (one is ok most of the time), at least for 'hosted' service, for better control on privileges. All service files should be owned by these accounts except the application launchers, which must be owned by root as they are executed with root privileges. The generic account home directory should be a link redirecting to a subdirectory of one of the service-dedicated filesystems (the one hosting data is a good candidate).

Select a service mode

hosted
Where virtualisation is unwanted : low-latency applications, restrictive product compatibility matrices, ...

zone/lxc/openvz/jail
Prefered mode where it is supported : quite low-latency, low mem and cpu overhead, good control of virtual system from the host system.

xen/kvm/hpvm/ldom
Sensible latency and memory overhead. Host system must rely on tcp/ip communication with the virtual machine to control its resources (change ip addresses, start service applications, ...)

Create a filesystem skeleton for the service

Here is a set of guidelines you should respect.

Give each service dedicated filesystems. Ideally one for data, one for tools (mysql, apache, ...) and one for launchers and eventually the virtual operating system instance. We recommand the following layout:
- /gieprdweb01 : app launchers in etc/init.d/
- /gieprdweb01/tools : private installation of tools. Tools must listen only on the private address to avoid conflicts with same tool of other services running on the same node.
- /gieprdweb01/data : application data files

For hosted service mode, prefer per-service private tools installations to enhance system/opt/opensvc insulation. This makes the service installation more painful, but there are no clients at this point, and it will make service relocation more reliable and operating system upgrades safer.

Install virtual host and applications

The virtual host is not required for 'hosted' services.

Create configuration files

Service configuration files are in /opt/opensvc/etc. Each service must have these three files present to be fully functional. Services using the internet shared collector must be named using the domainname as a suffix to avoid naming conflicts.

/opt/opensvc/etc/unxdevweb01.mydomain.com -> ../bin/svcmgr
/opt/opensvc/etc/unxdevweb01.mydomain.com.env
/opt/opensvc/etc/unxtstsvc01.mydomain.com.d -> /unxtstscv01/etc/init.d

Configuration files role

/opt/opensvc/etc/unxdevweb01.mydomain.com -> ../bin/svcmgr
This symbolic link is meant to be used as a shortcut to pass commands to a specific service. Like /opt/opensvc/etc/unxdevweb01.mydomain.com start for example

/opt/opensvc/etc/unxdevweb01.mydomain.com.env
This is the configuration file proper, including service description and resource definitions. A fully commented template is available on each node at /opt/opensvc/usr/share/doc/template.env. More on this below.

/opt/opensvc/etc/unxdevweb01.mydomain.com.d -> /unxtstscv01/etc/init.d
This symbolic link points to the directory hosting the service application launchers. The service is not considered active if this link is not present. The directory pointed is best hosted on a service-dedicated filesystem. The service application launchers are expected to be in SysV style: [SK][0-9]*appname. S for starters, K for stoppers, number for ordering. Starters and stoppers can be symlink to a single script. Starter are passed 'start' as first parameter, stoppers are passed 'stop' as first parameter.

Customize the service env file

There you should describe your service's ip adresses, filesystems, disk groups, file synchronizations ... The /opt/opensvc/usr/share/doc/template.env template presents you with all possible configurations available

Test

You should now be able to run succesfully

/opt/opensvc/etc/gieprdweb01 print_status
/opt/opensvc/etc/gieprdweb01 start
/opt/opensvc/etc/gieprdweb01 stop

OpenSVC

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