Action script sensors, and more broadly, any scripts executed via Instana's Action Framework, are run by the Instana agent process on the monitored host. The script inherits the user permissions, security context, and environment variables of the agent process itself. This is the default and fundamental execution model, allowing scripts to interact with the local system for tasks like data collection or remediation.

B. Logged in Instana user: The logged-in user interacts with the Instana UI to configure or trigger actions, but the script execution occurs on the remote host managed by the agent, not under the UI user's context.

C. Service agent: This is not a standard Instana term. The single Instana agent (host agent) is responsible for monitoring all services on a host and executing actions.

D. Container: While a script can be configured to execute within a specific container, its default execution context is the agent process itself, which typically runs on the host operating system.

1. IBM Instana Observability Documentation - Actions: "The script action executes a script on the agent that an event was detected on." This statement directly confirms that the agent is the execution context. (Source: IBM Documentation, Instana Observability, Section: Automate > Actions > Script).

2. IBM Instana Observability Documentation - Script Sensor: "The script is executed by the agent, and its output is parsed to create metrics that are displayed in the Instana UI..." This explicitly states the agent executes the script for custom metric collection. (Source: IBM Documentation, Instana Observability, Section: Application Monitoring > Sensors > Custom sensors > Script).