When Instana is integrated with Prometheus using the remotewrite API, Instana acts as a remote storage endpoint, ingesting metrics sent from a Prometheus server. The configuration options for this integration within the Instana agent allow users to define how these ingested metrics are displayed and correlated. Specifically, the user can choose to have the metrics appear as "Process Custom Metrics" attached to the application process that sent them, or they can be grouped and displayed under a distinct "Prometheus Entity" within the Instana UI. This provides flexibility for visualizing and analyzing Prometheus data in the context of the broader application landscape monitored by Instana.

A. To write data to Prometheus: This reverses the data flow. The remotewrite feature configures Prometheus to send data to Instana, not the other way around.

C. To configure remote access to Instana: This is too generic. The remotewrite configuration is specifically for the ingestion of time-series metric data, not for general remote access like UI or API management.

D. To display metrics as only a Prometheus Entity: This is incorrect because it presents only one of the two available options. The configuration allows for a choice between a Prometheus Entity and Process Custom Metrics.

1. IBM Instana Observability Documentation - Prometheus Integration:

Section: Prometheus > Monitoring > Configuration > Prometheus remote write API

Content: The documentation describes how Instana can be used as a remote endpoint for the Prometheus remotewrite API. It states, "The Instana agent listens on port 42699 for Prometheus remote write requests." This confirms Instana receives data.

Section: Prometheus > Monitoring > Metrics visibility

Content: This section details the two display options: "By default, Prometheus metrics are linked as Process Custom Metrics to the process that exposes them... Alternatively, the Prometheus sensor can create a Prometheus entity for each process instance that exposes Prometheus metrics." This directly supports the choice described in the correct answer. The configuration createprometheusentity: true is used to enable the latter option.