---
title: assembler bloom-filter create cli command
description: Build a bloom filter binary from a local legacy-docs repository. The bloom filter is a compact data structure that records which legacy URLs existed before...
url: https://docs-v3-preview.elastic.dev/elastic/docs-builder/pull/2927/cli/assembler/bloom-filter/create
products:
  - Elastic Docs Builder
---

# assembler bloom-filter create cli command
```bash
docs-builder assembler bloom-filter create --built-docs-dir <dir>
```

Build a bloom filter binary from a local legacy-docs repository.

## Options

<definitions>
  <definition term="--built-docs-dir string required">
    Path to the local legacy-docs repository checkout.
    **Constraints:** symbolic links not allowed, must exist, supports `~` home expansion
  </definition>
  <definition term="-l --log-level enum">
    Minimum log level.
    **Values:** trace, debug, information, warning, error, critical, none
    **Default:** `information`
  </definition>
  <definition term="-c --config-source enum">
    Override the configuration source: local, remote
    **Values:** local, remote, embedded
  </definition>
  <definition term="--[no-]skip-private-repositories">
    Skip cloning private repositories
  </definition>
</definitions>


## Notes

The bloom filter is a compact data structure that records which legacy URLs existed before migration.
It is used to verify redirect coverage: if a legacy URL is absent from the filter, any redirect
pointing to it cannot be validated. Run once after cloning the legacy-docs repository.