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Synthetics job manager configuration

Learn how to configure your synthetics job manager by using environment variables in your configuration.

Important

Custom modules, permanent data storage, and user defined environment variables are not supported for the synthetics job manager at this time.

As a note, New Relic is not liable for any modifications you make to the synthetics job manager files.

Environment variables

Environmental variables allow you to fine-tune the synthetics job manager configuration to meet your specific environmental and functional needs.

Sizing considerations for Kubernetes and Docker

Tip

Docker specific sizing considerations will be available soon.

If you're working in larger environments, you may need to customize the job manager configuration to meet minimum requirements to execute synthetic monitors efficiently. Many factors can impact sizing requirements for a synthetics job manager deployment, including:

  • If all runtimes are required based on expected usage
  • The number of jobs per minute by monitor type (ping, simple or scripted browser, and scripted API)
  • Job duration, including jobs that time out at around 3 minutes
  • The number of job failures. For job failures, automatic retries are scheduled when a monitor starts to fail to provide built-in 3/3 retry logic. These additional jobs add to the throughput requirements of the synthetic job manager.

In addition to the sizing configuration settings listed below, additional synthetics job managers can be deployed with the same private location key to load balance jobs across multiple environments.

Kubernetes

Each runtime used by the Kubernetes synthetic job manager can be sized independently by setting values in the helm chart.

Additional ping runtimes can be started to help execute ping monitor load by increasing the ping-runtime.replicaCount setting from the default value of 1.

The Node.js API and Node.js Browser runtimes are sized independently using a combination of the parallelism and completions settings. Ideal configurations for these settings will vary based on customer requirements.

The parallelism setting controls how many pods of a particular runtime run concurrently. The parallelism setting is the equivalent of the synthetics.heavyWorkers configuration in the containerized private minion (CPM). Ensure that your Kubernetes cluster has enough resources available to run this number of pods based on their resource request and limit values.

The completions setting controls how many pods of a particular runtime must complete before the CronJob can start another Kubernetes Job for that runtime. Note the difference between a Kubernetes Job (capital J) versus a synthetics monitor job. For improved efficiency, completions should be set to 6-10x the parallelism value. This can help to minimize the "nearing the end of completions" inefficiency where fewer than the parallelism number pods could end up running as the Kubernetes Job waits for all completions to finish.

When completions is greater than 1, pods with a "Completed" status will remain visible in the output of kubectl get pods -n YOUR_NAMESPACE until all completions defined in the Kubernetes Job have been met, for example 6/6 completions. Resources are released from the node when a pod has a status of Completed or Failed.

A Kubernetes Job age of 5 minutes (kubectl get jobs -n YOUR_NAMESPACE) is a conservative target to account for variability in how long it takes pods to complete and how many synthetics jobs need to run per minute (jobs rate). The following equations can be used as a starting point for completions and parallelism for each runtime. Adjustments may need to be made based on observations of private location queue growth.

completions = 300 / avg job duration (s)
parallelism = synthetics jobs per 5 minutes / completions

Different runtimes will likely have different synthetics job durations and rates. The following queries can be used to obtain average duration and rate for a private location.

# non-ping average job duration by runtime type
FROM SyntheticCheck SELECT average(duration) AS 'avg job duration' WHERE type != 'SIMPLE' AND location = 'YOUR_PRIVATE_LOCATION' FACET type SINCE 1 hour ago
# non-ping jobs per minute by runtime type
FROM SyntheticCheck SELECT rate(uniqueCount(id), 5 minutes) AS 'jobs per 5 minutes' WHERE type != 'SIMPLE' AND location = 'YOUR_PRIVATE_LOCATION' FACET type SINCE 1 hour ago

Tip

The above queries are based on current results. If your private location does not have any results or the job manager is not performing at its best, query results may not be accurate. In that case, try a few different values for completions and parallelism until you see a kubectl get jobs -n YOUR_NAMESPACE duration of at least 5 minutes (enough completions) and the queue is not growing (enough parallelism).

Example

Description

parallelism=1

completions=1

The runtime will execute 1 synthetics job per minute. After 1 job completes, the CronJob configuration will start a new job at the next minute. Throughput will be extremely limited with this configuration.

parallelism=1

completions=6

The runtime will execute 1 synthetics job at a time. After the job completes, a new job will start immediately. After the completions setting number of jobs completes, the CronJob configuration will start a new Kubernetes Job and reset the completions counter. Throughput will be limited, but slightly better. A single long running synthetics job will block the processing of any other synthetics jobs of this type.

parallelism=3

completions=24

The runtime will execute 3 synthetics jobs at once. After any of these jobs complete, a new job will start immediately. After the completions setting number of jobs completes, the CronJob configuration will start a new Kubernetes Job and reset the completions counter. Throughput is much better with this or similar configurations. A single long running synthetics job will have limited impact to the processing of other synthetics jobs of this type.

If synthetics jobs take longer to complete, fewer completions are needed to fill 5 minutes with jobs but more parallel pods will be needed. Similarly, if more synthetics jobs need to be processed per minute, more parallel pods will be needed. The parallelism setting directly affects how many synthetics jobs per minute can be run. Too small a value and the queue may grow. Too large a value and nodes may become resource constrained.

If your parallelism settings is working well to keep the queue at zero, setting a higher value for completions than what is calculated from 300 / avg job duration can help to improve efficiency in a couple of ways:

  • Accommodate variability in job durations such that at least 1 minute is filled with synthetics jobs, which is the minimum CronJob duration.
  • Reduce the number of completions cycles to minimize the "nearing the end of completions" inefficiency where the next set of completions can't start until the final job completes.

It's important to note that the completions value should not be too large or the CronJob will experience warning events like the following:

8m40s Warning TooManyMissedTimes cronjob/synthetics-node-browser-runtime too many missed start times: 101. Set or decrease .spec.startingDeadlineSeconds or check clock skew
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