3.6. Scanner — Apache CouchDB® 3.5 Documentation

# 3.6. Scanner

Configure background scanning plugins.

Added in version 3.4.

## 3.6.1. Scanner Options

[couch_scanner]
  interval_sec

    How often to check for configuration changes and start/stop plugins. The default is 5 seconds.

        [couch_scanner]
        interval_sec = 5

  min_penalty_sec

    Minimum time to force a plugin to wait before running again after a crash. Defaults to 30 seconds.

        [couch_scanner]
        min_penalty_sec = 30

  max_penalty_sec

    Maximum time to force a plugin to wait after repeated crashes. The default is 8 hours (in seconds).

        [couch_scanner]
        min_penalty_sec = 28800

  heal_threshold_sec

    If plugin runs successfully without crashing for this long, reset its repeated error count. Defaults to 5 minutes (in seconds).

        [couch_scanner]
        heal_threshold_sec = 300

  db_rate_limit

    Database processing rate limit. This will also be the rate at which design documents are fetched. The rate is shared across all running plugins.

        [couch_scanner]
        db_rate_limit = 25

  shard_rate_limit

    Limits the rate at which plugins may open db shard files on a node. The rate is shared across all running plugins.

        [couch_scanner]
        db_shard_limit = 50

  doc_rate_limit

    Limit the rate at which plugins open documents. The rate is shared across all running plugins.

        [couch_scanner]
        doc_rate_limit = 1000

  doc_write_rate_limit

    Limit the rate at which plugins update documents. This rate limit applies to plugins which explicitly use the `couch_scanner_rate_limiter` module for rate limiting

        [couch_scanner]
        doc_write_rate_limit = 500

  ddoc_batch_size

    Batch size to use when fetching design documents. For lots of small design documents this value could be increased to 500 or 1000. If design documents are large (100KB+) it could make sense to decrease it a bit to 25 or 10.

        [couch_scanner]
        ddoc_batch_size = 100

[couch_scanner_plugins]
  {plugin}

    Which plugins are enabled. By default plugins are disabled.

        [couch_scanner_plugins]
        couch_scanner_plugin_ddoc_features = false
        couch_scanner_plugin_find = false
        couch_quickjs_scanner_plugin = false

[{plugin}]

These settings apply to all the plugins. Some plugins may also have individual settings in their `[{plugin}]` section.

> after

>   Run plugin on or after this time. The default is to run once after the node starts. Possible time formats are: unix seconds (ex. `1712338014`) or date/time: `YYYY-MM-DD`, `YYYY-MM-DDTHH`, `YYYY-MM-DDTHH:MM`. Times are in UTC.

>       [{plugin}]
>       after = restart

> repeat

>   Run the plugin periodically. By default it will run once after node starts. Possible period formats are: `{num}_{timeunit}` (ex.: `1000_sec`, `30_min`, `8_hours`, `24_hour`, `2_days`, `3_weeks`, `1_month`) or `{weekday}` (ex.: `mon`, `monday`, `Thu`, etc.)

>       [{plugin}]
>       repeat = restart

> jitter

>   How much jitter to apply to the period. The default is 10% of the period value. Jitter can spread the load on the cluster by adding some randomness to when the plugins start. Possible formats are `{num}_percent` (ex.: `25_percent`) or `{num}_{timeunit}` (ex.: `1000_sec`, `30_min`, `8_hours`, `24_hour`, `2_days`). The default is `10_percent`, which means 10% of the period value

>       [{plugin}]
>       jitter = 10_percent

[{plugin}.skip_dbs]
  {tag}

    Skip over databases if their names match any of these regexes.

        [{plugin}.skip_dbs]
        regex1 = a|b
        regex2 = bar(.*)baz

[{plugin}.skip_ddocs]
  {tag}

    Skip over design documents if their DocIDs match any of these regexes.

        [{plugin}.skip_ddocs]
        regex1 = x|y|z
        regex2 = c(d|e)f

[{plugin}.skip_docs]
  {tag}

    Skip over documents if their DocIds match any of the regexes.

        [{plugin}.skip_docs]
        regex1 = k|l
        regex2 = mno$

[couch_scanner_plugin_find.regexes]
  {tag}

    Configure regular expressions to find. The format is {tag} = {regex} Reports will be emitted to the log as warnings mentioning only their tag. By default, no regular expressions are defined and the plugin will run but won’t report anything.

        [couch_scanner_plugin_find.regexes]
        regex1 = s3cret(1|2|3)
        regex2 = n33dl3

[couch_scanner_plugin_ddoc_features]
  updates

    Report if design documents have update handlers. Enabled by default.

        [couch_scanner_plugin_ddoc_features]
        updates = true

  shows

    Report if design documents have shows. Enabled by default.

        [couch_scanner_plugin_ddoc_features]
        shows = true

  rewrites

    Report if design documents have rewrites. Enabled by default.

        [couch_scanner_plugin_ddoc_features]
        rewrites = true

  filters

    Report if design documents have Javascript filters. Disabled by default.

        [couch_scanner_plugin_ddoc_features]
        filters = false

  reduce

    Report if design documents have Javascript reduce functions. Disabled by default.

        [couch_scanner_plugin_ddoc_features]
        reduce = false

  validate_doc_update

    Report if design documents have validate document update functions. Disabled by default.

        [couch_scanner_plugin_ddoc_features]
        validate_doc_update = false

  run_on_first_node

    Run plugin on the first node or all the nodes. The default is to run only on the first node of the cluster. If the value is “false” each node of the cluster will process a consistent subset of the databases so scanning will go faster but might consume more resources. Report if design documents have validate document update functions.

        [couch_scanner_plugin_ddoc_features]
        run_on_first_node = true

  ddoc_report

    Emit reports for each design doc or aggregate them per database. Emitting them per design doc will indicate the design document name, however if there are too many design documents, that may generate a lot of logs. The default is to aggregate reports per database.

        [couch_scanner_plugin_ddoc_features]
        ddoc_report = false