jboss-cli : How do I read one specific system property using jboss-cli?

Question

I'm new to jboss-cli and working through the 'jboss-cli recipes'.

Question

How do I read one specific property using jboss-cli? E.g.

• jboss.home.dir (e.g. "-Djboss.home.dir=/path/to/my/jboss")
• Xmx ("-Xmx=4G")

Context

The "CLI Recipes" documentation has this helpful example to get all system properties. However its 'too much infomration'. I want to script reading one specific property.

https://docs.jboss.org/author/display/WFLY10/CLI+Recipes#CLIRecipes-

Overview of all system properties in JBoss AS7+ including OS system properties and properties specified on command line using -D, -P or --properties arguments.

Standalone
[standalone@IP_ADDRESS:9999 /] /core-service=platform-mbean/type=runtime:read-attribute(name=system-properties)

Thanks in advance

Answer 1

You could do a :

:resolve-expression(expression=${jboss.home.dir})

Answer 2

You can use the cli like this:

$JBOSS_HOME/bin/jboss-cli.sh -c --command=/system-property=MY_PROPERTY:read-resource

you get an output like this:

$JBOSS_HOME/bin/jboss-cli.sh -c --command=/system-property=MY_PROPERTY:read-resource
{
    "outcome" => "success",
    "result" => {"value" => "4.0"}
}

which you can extract by piping into something like this:

<cli command>  | grep "{\"value\"" | sed "s/.*value\" => \"\([^\"]*\)\".*/\1/"

its a bit ugly, and there are some nasty edge cases if the values were to be something like "value" => "value =" or something hideous. In general this works OK.

Change the sed command to be a bit more specific to fix that.

Answer 3

You can also do it via Wildfly management rest call.

• http://localhost:9990/management
• POST
• Headers = Content-Type:application/json
• Body = { "operation":"resolve-expression", "expression":"${jboss.home.dir}" }

Answer 4

With newer Teiid DOCs I have found some useful information I thought this might be helpful to share to people coming across a similar usecase

https://access.redhat.com/documentation/en-us/jboss_enterprise_application_platform/6.3/html/administration_and_configuration_guide/configure_system_properties_using_the_management_cli

Helps Adding, Removing & Reading System Properties with jboss-cli

Answer 5

jboss-cli

If you have a cli command like ehsavoie suggested :resolve-expression(expression=${jboss.home.dir}) and want to use the content of the "result" property within jboss-cli you can save it in a variable. You can use backticks (`) to evaluate expressions.

simple expression

[standalone@localhost:9990 /] :resolve-expression(expression=${jboss.home.dir})
{
    "outcome" => "success",
    "result" => "/home/user/wildfly"
}

use in valiable

[standalone@localhost:9990 /] set wildflydirectory=`:resolve-expression(expression=${jboss.home.dir})`
[standalone@localhost:9990 /] echo $wildflydirectory
/home/user/wildfly

PowerShell

If you happen to use the PowerShell you can use a one-liner to extract even deeply nested results with the help of the cli's --output-json option and PowerShell's ConvertFrom-Json cmdlet. In this way the parsing problem from James Roberts's approach with grep and sed are gone.

$value=(Invoke-Expression "./jboss-cli.ps1 -c --command=':resolve-expression(expression=`${jboss.home.dir})' --output-json" | ConvertFrom-Json).result

It is a bit tricky to quote the command and escape the correct PowerShell special characters.