--- title: Charmhub | Deploy Generic Exporter using Charmhub - The Open Operator Collection description: Deploy the latest version of Generic Exporter on any cloud. url: https://charmhub.io/generic-exporter-operator/docs/system-architecture --- # Generic Exporter [Iurii Kondrakov](https://charmhub.io/publisher/deezzir "View all packages from Iurii Kondrakov") * [Iurii Kondrakov](https://charmhub.io/publisher/deezzir "View all packages from Iurii Kondrakov") Platform: 24.04 22.04 dev/edge 58 ``` juju deploy generic-exporter-operator --channel dev/edge ``` [Learn to deploy on juju >](https://juju.is/docs/juju/manage-applications) --- #### Relevant links * [Homepage](https://charmhub.io/velero-operator) --- #### Contacts * [Submit a bug](https://github.com/canonical/generic-exporter-operator/issues) --- Share your thoughts on this charm with the community on discourse. [Join the discussion](https://discourse.charmhub.io/) # System architecture This guide describes the main components and responsibilities of the Generic Exporter operator. At a high level, the charm: * Manages the lifecycle of **one exporter snap per unit** * Validates and applies charm configuration to the snap * Exposes a configurable HTTP metrics endpoint (port and path) * Integrates with COS via Opentelemetry Collector using the `cos-agent` relation * Optionally consumes an `alerts` resource and forwards the contained rules to COS ## [Core components](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-core-components) ### [Snap Manager](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-snap-manager) The charm uses `charmlibs.snap` to install, refresh, configure, and remove the exporter snap. Responsibilities include: * Ensuring the requested snap is present using `SnapCache` and `snap.ensure` * Installing from either a **channel** or a **revision** (but not both simultaneously) * Applying configuration via `snap.set`/`snap.unset` based on the `snap-config` charm option * Managing snap removal during charm teardown ### [Snap Singleton](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-snap-singleton) Ensures that the charm application can be safely scaled up and down without affecting peers: * Tracks snap registrations by units in a lock file under `/opt/singleton_snaps` directory. * Manages exclusive access to singleton snaps and configuration files using file-based locks. ### [Exporter Configurator](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-exporter-configurator) Charm configuration is validated and translated into a concrete snap configuration: * **Port and path**: the charm exposes metrics on `http://:/`. * **Snap configuration**: arbitrary exporter settings can be provided as a JSON blob in `snap-config`, which is parsed and passed to `snap.set()`. * **Snap plugs**: the `snap-plugs` option allows automatically connecting required interfaces after installation (for example, network access or system metrics). Invalid configuration (for example, malformed JSON or conflicting `snap-channel`/`snap-revision`) is detected early and results in a `Blocked` status with a clear message. ### [COS integration layer](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-cos-integration-layer) The Generic Exporter operator uses the `COSAgentProvider` abstraction from the `cos_agent` library to expose metrics and alert rules over the `cos-agent` relation. In effect, the charm: * Registers a metrics endpoint (path and port) for the Opentelemetry Collector to scrape. * Points Opentelemetry Collector to an on-disk directory (for example, `/run/-/alerts.yaml`) containing alert rule files. * Triggers refreshes of scrape configuration and rules on relevant events (such as `config-changed`). Opentelemetry Collector is responsible for forwarding telemetry to COS Lite and enriching metrics and alerts with Juju topology labels. ### [Resource Manager](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-resource-manager) The charm optionally consumes an `alerts` resource: * When attached, the resource file (YAML) is fetched via `self.model.resources.fetch("alerts")`. * The content is parsed and written into a rules file, typically `alerts.rules`, under a dedicated directory like `/run/-/alerts.yaml`. * Missing resources are handled gracefully and logged at the warning level. The design explicitly **avoids** shipping dashboards or snap files as resources: * Dashboards are expected to be managed through COS and Grafana directly. * Installing local snap files using `--dangerous` was rejected for security and supportability reasons. ## [Subordinate model](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-subordinate-model) The Generic Exporter operator is implemented as a **subordinate machine charm**: * It relates to any principal via `juju-info` (or an equivalent relation) and is co-located with the principal units. * Operators can deploy multiple applications of the Generic Exporter operator (for example, one per exporter type) on the same machine. ## [Versioning](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-versioning) The charm’s workload version is aligned with the installed exporter snap version: * The charm queries `snap info` for the exporter and sets `workload_version` accordingly (for example, `node-exporter/1.6`). * The snap is pinned to the selected channel or revision; upgrading the exporter is performed explicitly by changing the charm configuration. ## [Limitations (design intent)](https://charmhub.io/generic-exporter-operator/docs/system-architecture#p-40635-limitations-design-intent) The current design assumes: 1. **Machine-only**: No Kubernetes support. 2. **One exporter per unit**: The charm does not orchestrate multiple exporters within the same subordinate. 3. **Snap auto-start**: The exporter snap is expected to start its service automatically upon installation and expose the metrics via an HTTP endpoint. 4. **Config-driven updates**: Snap updates are controlled via charm configuration rather than automatic refresh. 5. **Port configuration**: Exporters should allow their listening port to be configured to avoid conflicts when multiple exporters are deployed on the same machine. ---