Service Application Launchers

Introduction

An application launcher is a resource. As such, it supports the standard start, stop and status actions. Application resources are also involved in the push appinfo action. Application launchers can support the following parameters:

Service action Launcher parameter
start start
stop stop
status print status json status status
push appinfo info

As a resource, an application launcher can be defined with a <svcname>.env section. This method permits complex application scheduling, mixing chaining and parallel execution, timeouts setting and scoping.

For simple cases, the agent also supports a SysV-style launcher definitions.

Note

SysV-style definitions can co-exist with non-conflicting app resources defined in the env file. In case of conflicting definitions, the env file definition takes precedence.

Application Resource Definition

Section Syntax

Here is a complete application resource section:

[app#1]
script = weblogic
start = 50
stop = 50
check = 50
info = 50
disable = false
optional = true
tags = group1
subset = web
# rlimits
limit_as = 1g
limit_cpu = 1-4
limit_core = 1-4
limit_data = 1g
limit_fsize = 5t
limit_memlock = 1k
limit_nofile = 10k
limit_nproc = 10k
limit_rss = 100m
limit_stack = 10m
limit_vmem = 100m

All these parameters support scoping, using the @<nodename>, @nodes, @drpnodes and @encapnodes suffixes.

Parameter Type Role
script string Full path the the app launcher or basename of a launcher in etc/<svcname>.d/.
start integer Flag the app launcher for execution with the start parameter on service startup. The given value is used as the ascending sort key in the resource subset. Omit the parameter to disable app launcher execution on resource start action.
stop integer Flag the app launcher for execution with the stop parameter on service stop. The given value is used as the ascending sort key in the resource subset. Omit the parameter to disable app launcher execution on resource stop action.
status integer Flag the app launcher for execution with the status parameter on service status evaluation. The given value is used as the ascending sort key in the resource subset. Omit the parameter to disable app launcher execution on resource status action.
info integer Flag the app launcher for execution with the info parameter on service push appinfo. The given value is used as the ascending sort key in the resource subset. Omit the parameter to disable app launcher execution on resource appinfo action.
subset string Add the resource to the specified app subset. In the given example, the full subset name is subset#app:web
limit_* string Refer to the OS man limits.conf

App Subsets

  • Actions on subsets are chained in alphanumeric subset name order on start, status and info.
  • Actions on subsets are chained in reverse alphanumeric subset name order on stop.
  • The implicit subset name is subset#app.
  • Scripts in a subset are executed either in parallel or serially (default).

Here is a subset section:

[subset#app:web]
parallel = true

Application can be started and stopped without touching the other service resources with:

sudo svcmgr -s myservice stopapp
sudo svcmgr -s myservice startapp

The OPENSVC_SVCNAME variable is set by OpenSVC to the service name, so that integrators can write reusable launcher scripts. Examples of this variable usage below.

Environment variable named OPENSVC_IP<n> are also set to let app launchers bind the appropriate service ips, for services with instances on different subnets. For example, the service might have a different ip address when starting on the disaster recovery site.

Launcher Scripts Development Guidelines

A launcher script should support the following values for argument 1:

Arg1 Description
start Triggers the application startup. The return code must be 0 for a succesful startup, and not 0 otherwise.
stop Triggers the application shutdown. The return code must be 0 for a succesful shutdown, and not 0 otherwise.
status Return 0 if the application is up, or any other value if the application is not up. In this later case, the agent will report a warn status for the resource.
info Emits on stdout key: value pairs. These pairs will be reported to the collector for storage, and historization if the value is numeric.