You only need a Host Monitoring Agent if no other Agent runs on that particular machine, because any other active Agent except Node.js delivers those metrics.
The Web Server master Agent only delivers when a slave / sub- Agent is connected to it.
With many Agents on one machine, you may want to switch off delivery of host monitoring data from non-Host-Agents to reduce traffic from Agent to Collector. See support for the best strategy.
Restart Host Agents from the Client’s Agent Overview / Status dashboard > Host Agent context menu.
For AppMon 6.5 and later, the Host Monitoring Agent can monitor availability of any process running on the host. For further information on process availability monitoring see information on configuration of hosts/host groups on the Infrastructure page.
The Windows full package installer installs the Host Agent, but the service is not registered due to the potential redundant Host Agent role mentioned previously. You can register the Host Agent with "<DT_HOME>\agent\lib\dthostagent" -service install. Copy and paste this example for 32-bit Host Agent service from a 64-bit AppMon full installation:
Unregister the Agent with sc delete "dynaTrace Host Agent7.0".
With the Agent-only installer, you must custom install the Host Agent to be installed and registered for auto-start. This lets you monitor the machine with no other Agent running on it. The default <DT_HOME> is C:\Program Files (x86)\dynaTrace\dynaTrace Agent 7.0, including the 64-bit libraries in agent\lib64.
On *NIX, use cd /opt and java -jar <DownloadDir>/<dynatrace(Agent)Installer.jar>. The installer defaults to the current directory and asks if you want to change the destination. Make sure you have the correct permissions for installation and to write to the target location.
<DT_HOME> is /opt/dynatrace-7.0 or /opt/dynatrace-agent-7.0, for the full or Agent-only installer respectively. The <DT_HOME>/init.d/dynaTraceHostAgent shell script should be copied to or referenced in (link) /etc/init.d and added to the system boot by using something similar chkconfig or update-rc.d, depending on your distribution.
Configuration must be done by editing the <DT_HOME>/agent/conf/dthostagent.ini:
Key
Default
Description
Name
host
Agent name, can be used to map an Agent to a specific Agent Group.
The AppMon standalone or Server-embedded Collector to which this Agent should connect.
The argument name “Server” stems from past releases when the Collector was Server-integrated. Most licenses allow only standalone Collectors, except for testing.
Loglevel
info
Define log level.
ConsoleLoglevel
info
Define console log level.
LogfilePath
<agent location>/log
Specify a custom log file.
OverrideHostname
<not set>
Specify a custom hostname, if set this prevents the Agent from auto detecting the hostname.
usessl
false
Enables SSL encryption between the Agent and the Collector. Encrypted communication uses the same port as non-encrypted. To enable SSL you need to set this parameter as true before launching the Agent.
Example basic dthostagent.ini
The following is an example <DT_HOME>/agent/conf/dthostagent.ini file. This file configures the Host Monitoring Agent named host (default) to connect to the AppMon Server (actually stand-alone or Server-integrated / embedded Collector) with the fully qualified name dtcollector.localdomain.com on port 9998.
Name host
Server dtcollector.localdomain.com:9998
Agent bulk installation
To monitor a large number hosts in the hundreds, you can automate the Host Agent deployment.
Perform a (custom) installation with the full or Agent-only .msi, or use dthostagent.exe and dtagentcore.dll and dthostagent.ini in the directory structure.
If you use the installer with msiexec /passive /i <path>\<dynaTraceInstallerFileName>.msi ADDLOCAL="HostAgent", then Host Agent registers as an auto-starting service with the default settings from dthostagent.ini.
You can rewrite dthostagent.ini and un/register the service with the new arguments.
If you just use the .exe and .dll, you can write your own dthostagent.ini and register the service to auto-start with <DT_HOME>\agent\dthostagent.exe -service install.
#extract dthostagent and libdtagentcore.so from agent/lib64/ in the jar
#extract init.d/dynaTraceHostagent from the jar
#mimic Agent directory structure on the host
mkdir dynatrace-agent-7.0.0
mkdir dynatrace-agent-7.0.0/agent
mkdir dynatrace-agent-7.0.0/agent/lib64
mkdir dynatrace-agent-7.0.0/agent/conf
#copy dthostagent and libdtagentcore.so to agent/lib64/
#write a basic dthostagent.ini (see above) to agent/conf
#copy dynaTraceHostagent shell script to /etc/init.d
#be sure the Name specified in dthostagent.ini is mapped in some tier to avoid an error message
#try the Agent before you add it to boot
#/etc/init.d/dynaTraceHostagent start
chkconfig add dynaTraceHostagent
