Preparing a StackPack provisioning script

This page describes StackState version 4.0.

The StackState 4.0 version range is End of Life (EOL) and no longer supported. We encourage customers still running the 4.0 version range to upgrade to a more recent release.

Go to the documentation for the latest StackState release.

The provisioning script that is used for provisioning the StackPack should extend from com.stackstate.stackpack.ProvisioningScript. The provisioning script can be split into multiple groovy scripts. The provisioning directory inside the StackPack is part of the classpath, so any groovy script referred to inside the provisioning directory is also loaded.

A provisioning script is provided with a set of capabilities that it can execute in the StackState environment. The capabilities are restricted to those that are defined as part of com.stackstate.stackpack.ProvisioningContext which is passed as a constructor parameter for the ProvisioningScript.

Here is an example of a provisioning script:

import com.stackstate.stackpack.ProvisioningContext
import com.stackstate.stackpack.ProvisioningIO
import com.stackstate.stackpack.ProvisioningScript
import com.stackstate.stackpack.ProvisioningIO$
import com.stackstate.stackpack.Version

class SomeProvisioningScript extends ProvisioningScript {
  SomeProvisioningScript(ProvisioningContext context) {
      super(context)
  }

  @Override
  ProvisioningIO<scala.Unit> preInstall(Map<String, Object> config) {
    // Return any action that needs to run globally for this StackPack.
  }

  @Override
  ProvisioningIO<scala.Unit> install(Map<String, Object> config) {
    // Return any action that needs to run per StackPack instance.
  }

  @Override
  ProvisioningIO<scala.Unit> upgrade(Map<String, Object> config, Version previousVersion) {
    // Return any action that needs to be done when upgrading each instance from `previousVersion` to the latest.
  }

  @Override
  ProvisioningIO<scala.Unit> uninstall(Map<String, Object> config) {
    // Return any action that needs to run per StackPack instance.
  }

  @Override
  ProvisioningIO<scala.Unit> postUninstall(Map<String, Object> config) {
    // Return any action that needs to run globally for this StackPack.
  }

  @Override
  void waitingForData(Map<String, Object> config) {
    // Determine wether sufficient data has reached StackState.
  }
}

The supported actions are:

• preInstall - this action is run when installing the very first instance of a StackPack - it is meant to install all the objects that each of the instances will share.

• install - this action is run for every installed instance of a StackPack - it is meant to install instance-specific objects, that will be of use for this instance only.

• waitingForData - this action allows the StackPack creator to check wether any external service that this StackPack communicates with is properly sending data that this StackPack can process. By default it just transitions to the INSTALLED state.

• upgrade - this action is run for every installed instance of a StackPack when the user upgrades their StackPack version.

• uninstall - this action is run for every instance when it is being uninstalled - it is meant to clean up all the instance-specific objects.

• postUninstall - this action is run when uninstalling the very last instance of a StackPack - it is meant to clean up all the StackPack-shared objects.

Provisioning script context

A set of useful objects for the above actions are exposed via the provisioning context accessible via the context() function.

The provisioning script can interact with the provisioning via the context() function:

context()

The context() function returns an object that provides the following functions:

• scriptsDirectory() - returns the path to the directory where this script resides.

• fail(errorMessage) - marks this StackPack instance as broken (StackPack is in ERROR state) with errorMessage error message.

The StackState (sts) object

The provisioning script can interact with the StackState instance it is running in via the sts() function:

context().sts()

The sts() function returns an object that provides the following functions:

• intakeApi() - returns an object representing the StackState intake API that receives incoming data. The object supplies functions apiKey() (returns the API key for the intake API) and baseUrl() (returns the base URL for the intake API).

• log() - allows logging to be done in the provisioning script. Example: context().sts().log().debug("Installing test StackPack").

• install(stackpackName, parameters) - triggers installation of StackPack stackpackName with parameters parameters.

• onDataReceived(topic, callback) - runs a callback function whenever data is received by the StackState API on topic topic.

• provisioningComplete() - called when provisioning is done, marks this StackPack instance state as INSTALLED.

• createTopologyTopicName(sourceType, sourceId) - formats a StackState Kafka topic name using sourceType and sourceId parameters.

The StackPack (stackPack) object

The provisioning script can interact with the StackPack being installed via the stackPack() function:

context().stackPack()

The stackPack() function returns an object that provides the following functions:

• importSnapshot(filename, parameters) - imports a template from filename in the StackPack's namespace, filling in the optional parameters substitutions.

The StackPack instance (instance) object

The provisioning script can interact with the StackPack instance being installed via the instance() function:

context().instance()

The instance() function returns an object that provides the following functions:

• id() - returns the current StackPack instance id.

• importSnapshot(filename, parameters) - imports a template from filename in the StackPack's namespace, filling in the optional parameters substitutions.

The environment (env) object

The provisioning script can interact with the StackState environment via the env() function:

context().env()

The env() function returns an object that provides the following functions:

• execute(commandLine, directory, environment) - runs a shell script command commandLine in directory with environment setup.

How to ensure consistency between the provisioning script and the template file

It is time to template out the variables exposed by your StackPack. It is possible to define some input fields that your StackPack requires to authenticate against some external sources and to differentiate between instances. To generalize the configuration, it is needed to inject the configuration file with some template parameters which are provided by the provisioning script. Any parameters or configuration item can be passed down to the .stj template file.

One common example is to create the topic name required by the data source for a given instance. To ensure data received from the StackState Agent Check ends up in your StackPack's data source, make sure that you create the same topic in the provisioning script. The following code snippet shows how to create a function called topicName that generates a topic name for this instance, based on the data provided by the user in the StackPack installation step.

@Override
ProvisioningIO<scala.Unit> install(Map<String, Object> config) {
    def templateArguments = [
        'topicName': topicName(config),
        ... more template variables here ...
    ]
    // we place all the config variables in our template arguments as well.
    templateArguments.putAll(config)

    return context().sts().importSnapshot(context().stackPack().namespacePrefix(), "templates/{stackpack}.stj", templateArguments)
}

private def topicName(Map<String, Object> stackpackConfig) {
    def instance_url = stackpackConfig.instance_url
    def topic = instance_url.replace("/", "_").replace(":", "_")
    return context().sts().createTopologyTopicName("your_instance_type", topic)
}

It is possible now to reference any of the above templateArguments in your .stj template file. In case of the topicName you can replace the topic value in the config section of your StackState DataSource with this parameter:

{
    "_type": "DataSource",
    "name": "StackPack Data Source",
    "identifier": "urn:stackpack:stackpack_name:data-source:stackpack_data_source",
    "config": {
      ...
      "topic": "{{ topicName }}"
    },
    ...
}