This agent can monitor several parameters of PostGres database servers. It has been tested on different versions. However, we recommend checking its functionality before implanting it in a production environment.

PostGres agent has been developed using functionalities and enhancements of Osmius framework and ACE libraries, so it is necessary to install the ACE libraries for the proper deployment and operation of this Osmius agent. See chapter: installation.

In addition this agent uses PostGre development libreries, if you want to compile by yourself you need to install it previously. Take a look: prerequisites section

POSTGRES agent provides up to 4 basic events with configuration parameters to allow scaling of a very simple way.

All events are remote, so not intrusive. Monitoring is done through the network connection, by this reason you have to provide some connection information, see: connection info. Events are based on remote queries.

As a general rule each Osmius agent can monitor one instance type. If you are not familiar with these concepts check out the glossary. Each instance is individually defined in the configuration file (if you want further information go to agents and instances); depending on agent type is the instance type and depending on instance is the connection info.

The connection information or connection_info is data that the agent needs to know to connect to the instance. (See more about the connection_info)

In PostGres Osmius agent the connection_info prototype would be:

CONNECTION_INFO= -u USER -p PASSWORD -d DATABASE [-a IP_ADDRESS] [-l PORT]

Replace the following:

• USER: user name. Mandatory.
• PASSWORD: password. Mandatory.
• DATABASE: target database name. Mandatory.
• IP_ADDRESS: hostname or IP Address. Default localhost. Optional.
• PORT: PostGres listening port. Default 5432. Optional.

Examples:

CONECTION_INFO = -u usr01 -p pass01 -d db01
CONECTION_INFO = -u usr01 -p pass01 -d db01 -a 192.168.13.13
CONECTION_INFO = -u usr01 -p pass01 -d db01 -a 192.168.13.13 -l 2324

The type defines the instance type to be monitored. Every declared instance must be associated with a type as you can see here

In this case:

TYPE= POSTGRES

Here is briefly the capabilities of this agent, further down on this page each event is described in more detail.

• If you want capacity plannings unset silent mode in events

The event AVAILABL checks the availability of the connection to the Postgres database. If there is availability returns 0, otherwise returns 1.

Return values:

Recommended parameters:

Parameter setting example:

AVAILABL = -t 60 -c 0 -w 1 -a 1 -T "PostGres version and host type"

Remarks: The event text will show PostGres version.

The event PGNUMCON returns the number of current connections to the database.

Return values:

Recommended parameters:

Parameter setting example:

PGNUMCON = -t 300 -c 0 -w 1 -a 1 -T "Connections"

Remarks: None

The event PGPRCCON returns the current percentage of maximum connections.

Return values:

Recommended parameters:

Parameter setting example:

PGPRCCON = -t 300 -c 0 -w 1 -a 1 -T "connections percentage"

Remarks: None

The event PGDATMBS gives the size of the database in MB.

Return values:

Recommended parameters:

Parameter setting example:

PGDATMBS = -t 86400 -c 0 -w 1 -a 1 -T "db MB"

Remarks: None

In order to compile, this agent requires a set of prerequisites, which are generic to compile any Osmius agent, you can see these prerequisites.

PostGre agent needs PostGre development libraries in order to compile. There is a lot of information about it outside.

You also needs database access.

• Make Project Creator (MPC) is used by Osmius, so creating Makefiles is a trivial task. If you want to learn more about MPC and Osmius check out the section of Makefiles on Osmius.

• For PostGres Osmius agent you can generate Makefile in this way:

Modify osm_ag_postgres.mpc:

// -*- MPC -*-
// $Id$
project(*Osmius) : aceexe, ace_openssl {
  exename = osm_ag_POSTGRES
  install = $(OSM_ROOT)/bin
  after  += ACE_SSL_lib
  libs   += ACE_SSL

// Postgress: Take a look at 
//   http://www.postgresql.org/docs/8.1/static/libpq-build.html
//   execute: pg_config
// Postgresql :: Linux  
  includes += /usr/include/postgresql  
//libpaths += <path_to_postgres_library>
  libs   += pq

  Source_Files {
   ./../../cm/osm_cfgmanager.cpp
   ./../../cm/osm_message.cpp
   ./../../cm/osm_reactor.cpp
   ./../../ag/osm_ag_insmanager.cpp
   ./../../ag/osm_ag_msgmanager.cpp
   ./../../ag/osm_agent_basic.cpp
   osm_ag_postgres.cpp
  }
  Header_Files {
   ./../../cm/osm_cfgmanager.h
   ./../../cm/osm_message.h
   ./../../cm/osm_reactor.h
   ./../../ag/osm_ag_insmanager.h
   ./../../ag/osm_ag_msgmanager.h
   ./../../ag/osm_agent_basic.h
   osm_ag_postgres.h
  }
}

From the agent directory using console or terminal.

$ACE_ROOT/bin/mpc.pl -type make osm_ag_postgres.mpc

• Now that you have created the Makefile, agent compiling is extremely simple.

make -f Makefile.Osm_Ag_Postgres_Osmius

Binaries are automatically installed in the bin directory of OSM_ROOT base directory.

PostGres agent have the same running features of the other Osmius agents. You can check it out int he section Start and Stop Agents.

To run PostGres agent without Osmius web console:

PostGres Osmius agent, like the others Osmius agents, allows the execution in standalone mode. This option may be particularly useful when developing a new agent or to perform specific agent tests.

Basically you have to add a new value, called SNDCMD, to Osmius agent configuration file agente de Osmius para PostGres (osm_ag_POSTGRES.ini) as shown here.

Then you have to run PostGres Osmius agent setting Master Agent communications port to zero, for example:

Test performed to PostGres Osmius agent.