Add readme for otel-signal-viewer plugin. (#21734)
* Add readme for otel-signal-viewer plugin. * Remove duplicate word.
vkalintiris committed
Feb 16, 2026 at 15:24 UTC
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src/crates/netdata-log-viewer/otel-signal-viewer-plugin/README.md
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+# OpenTelemetry Signal Viewer (otel-signal-viewer.plugin)
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+
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+The `otel-signal-viewer` plugin is a [Netdata](https://github.com/netdata/netdata) external plugin
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+that reads, indexes, and visualizes OpenTelemetry logs stored in
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+`systemd`-compatible [journal files](https://systemd.io/JOURNAL_FILE_FORMAT/)
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+written by the [`otel`](../../netdata-otel/otel-plugin/README.md) plugin.
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+
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+> These journal files can also be inspected directly with
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+> [`journalctl`](https://www.freedesktop.org/software/systemd/man/latest/journalctl.html).
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+> Note that the output will contain logs with remapped field names for
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+> `systemd`-compatibility.
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+
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+## Configuration
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+
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+Edit the [otel-signal-viewer.yaml](https://github.com/netdata/netdata/blob/master/src/crates/netdata-log-viewer/otel-signal-viewer-plugin/configs/otel-signal-viewer.yaml.in)
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+configuration file using `edit-config` from the Netdata
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+[config directory](/docs/netdata-agent/configuration/README.md#locate-your-config-directory),
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+which is typically located under `/etc/netdata`.
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+
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+```bash
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+cd /etc/netdata # Replace this path with your Netdata config directory
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+sudo ./edit-config otel-signal-viewer.yaml
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+```
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+
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+### Journal
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+
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+The `journal` section specifies the directories containing journal files to
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+watch and index. By default, it points to the same directory the `otel`
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+plugin uses to store OpenTelemetry logs. At least one path must be specified:
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+
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+```yaml
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+journal:
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+ paths:
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+ - "/var/log/netdata/otel/v1"
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+```
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+
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+### Cache
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+
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+The `cache` section configures the hybrid memory and disk cache used for
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+indexed journal data.
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+
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+| Option | Default | Description |
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+|--------------------|-----------------------------------|------------------------------------------------------|
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+| `directory` | `/var/cache/netdata/otel-signal-viewer` | Directory to store the disk-backed cache |
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+| `memory_capacity` | `1000` | Number of indexed journal files to keep in memory |
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+| `disk_capacity` | `32MB` | Maximum size of the disk-backed cache |
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+| `block_size` | `4MB` | Size of individual cache blocks |
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+| `workers` | number of CPU cores | Number of background workers for indexing |
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+| `queue_capacity` | `100` | Queue capacity for pending indexing requests |
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+
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+```yaml
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+cache:
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+ directory: "/var/cache/netdata/otel-signal-viewer"
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+ memory_capacity: 1000
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+ disk_capacity: "32MB"
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+ block_size: "4MB"
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+ # workers: <number-of-CPU-cores>
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+ queue_capacity: 100
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+```
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+
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+### Indexing
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+
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+The `indexing` section controls how journal fields are indexed, with limits to
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+prevent unbounded memory growth from high-cardinality fields.
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+
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+| Option | Default | Description |
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+|--------------------------------|---------|--------------------------------------------------------------|
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+| `max_unique_values_per_field` | `500` | Maximum unique values to index per field |
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+| `max_field_payload_size` | `100` | Maximum payload size (in bytes) for field values to index |
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+
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+```yaml
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+indexing:
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+ max_unique_values_per_field: 500
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+ max_field_payload_size: 100
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+```