Cleaner method to pass parameters to a simulation from a command invocation using SBT

Gatling (Open-Source)
1

Hi,

Currently I use this approach to define and pass in simulation parameters:

`

val RAMP_UP_START : Double =
System.getProperty(“loadbalancedworkload.rampUpUsersPerSecStart”).toDouble

val RAMP_UP_END : Double =
System.getProperty(“loadbalancedworkload.rampUpUsersPerSecEnd”).toDouble

val RAMP_UP_TIME_SECS: Int =
Integer.getInteger(“loadbalancedworkload.rampUpDurationSecs”)

val STEADY_STATE: Double =
System.getProperty(“loadbalancedworkload.steadyStateUsersPerSec”).toDouble

val STEADY_TIME_SECS: Int =
Integer.getInteger(“loadbalancedworkload.steadyStateDurationSecs”)

…

`

I use the SBT project structure, with the gatling-sbt plugin, I haven’t found a convenient way to pass the parameters, so I do it this way, using a bash script:

`

export JVM_OPTS="
-XX:+CMSClassUnloadingEnabled
-XX:PermSize=512M -XX:MaxPermSize=1024M
-Dsbt.log.noformat=true"

HTTP_METHOD=‘GET’
HTTP_URLS=‘http://localhost:8080,http://localhost:8080’ # Comma separated baseURls
HTTP_RESOURCE_PATH=’/json’
RUN_NAME=‘HelloGoLoadBalanced’
PAGE_NAME=‘json’

RAMP_UP_USERS_PER_SEC_START=‘1.0’ # Must be a floating-point number string
RAMP_UP_USERS_PER_SEC_END=‘1000.0’ # Must be a floating-point number string
RAMP_UP_DURATION_SECS=‘30’ # Must be an integer string. No decimal point
STEADY_STATE_USERS_PER_SEC=‘1000.0’ # Must be a floating-point number string
STEADY_STATE_DURATION_SECS=‘300’ # Must be an intenger string. No decimal point
RAMP_DOWN_USERS_PER_SEC_START=‘1000.0’ # Must be a floating-point number string
RAMP_DOWN_USERS_PER_SEC_END=‘1.0’ # Must be a floating-point number string
RAMP_DOWN_DURATION_SECS=‘1’ # Must be an integer string. No decimal point

if [ -z “$HTTP_URLS” ]
then
echo “HTTP_URLs is unset. Open start.sh and set a valid URL”
exit 1
fi

SBT_CMD="; set javaOptions ++= Seq("-XX:PermSize=512M",
“-XX:MaxPermSize=1024M”,
“-Xms4096m”, “-Xmx7224m”,
“-Dsun.net.inetaddr.ttl=0”,
“-Djava.net.preferIPv4Stack=true”,
“-Djava.net.preferIPv6Addresses=false”,
“-Dloadbalancedworkload.method=${HTTP_METHOD}”,
“-Dloadbalancedworkload.baseURLs=${HTTP_URLS}”,
“-Dloadbalancedworkload.resourcePath=${HTTP_RESOURCE_PATH}”,
“-Dloadbalancedworkload.scenarioName=${RUN_NAME}”,
“-Dloadbalancedworkload.pageName=${PAGE_NAME}”,
“-Dloadbalancedworkload.rampUpUsersPerSecStart=${RAMP_UP_USERS_PER_SEC_START}”,
“-Dloadbalancedworkload.rampUpUsersPerSecEnd=${RAMP_UP_USERS_PER_SEC_END}”,
“-Dloadbalancedworkload.rampUpDurationSecs=${RAMP_UP_DURATION_SECS}”,
“-Dloadbalancedworkload.steadyStateUsersPerSec=${STEADY_STATE_USERS_PER_SEC}”,
“-Dloadbalancedworkload.steadyStateDurationSecs=${STEADY_STATE_DURATION_SECS}”,
“-Dloadbalancedworkload.rampDownUsersPerSecStart=${RAMP_DOWN_USERS_PER_SEC_START}”,
“-Dloadbalancedworkload.rampDownUsersPerSecEnd=${RAMP_DOWN_USERS_PER_SEC_END}”,
“-Dloadbalancedworkload.rampDownDurationSecs=${RAMP_DOWN_DURATION_SECS}”,
“-Dgatling.core.outputDirectoryBaseName=${RUN_NAME}”) ; testOnly meteorfox.benchmarks.LoadBalancedOpenModelWorkload"

sbt “${SBT_CMD}”

`

As you can see this is really verbose, I’m looking for a more cleaner approach, where perhaps, I could define these parameters in a file, but are overwritten by the environment variables.

Does anybody has figured out a cleaner way to achieve this? Ideally I want to keep using SBT.

Thanks,
Carlos Torres

2

HI Carlos,

You can use typesafe config library for this, it allows to override static values with env variables if they set.
Just add this lib to your project.
Then create application.conf in src\test\resourses

loadbalancedworkload {

rampUpUsersPerSecStart = 1.0
rampUpUsersPerSecStart = ${?`````````RAMP_UP_USERS_PER_SEC_START`}

}

And read them in your simulation:

val config = ConfigFactory.load()
val RAMP_UP_START = config.getDouble("loadbalancedworkload.rampUpUsersPerSecStart")

Regards,
Alex.

3

Beautiful, this is exactly what I was looking for.

Thanks Alex!