Expose configuration option for server_names_hash_bucket_size in LemonLDAP-ng Docker image

[Zorin95670]

Description

Problem

When running LemonLDAP-ng inside Docker with multiple or long domain names, the embedded NGINX instance may fail to start with the following error:

[emerg] could not build server_names_hash,
you should increase server_names_hash_bucket_size: 64

This happens because the default NGINX configuration uses a fixed server_names_hash_bucket_size, which is too small for environments with long fully qualified domain names.

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Impact

• LemonLDAP-ng container fails to start
• Authentication service becomes unavailable
• OpenID Connect endpoints are unreachable
• Cascading failures in dependent applications (OIDC login loops, 302 redirects, UI errors)

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Current limitation

At the moment, there is no supported way to configure this NGINX parameter through:

• LemonLDAP-ng configuration JSON
• Environment variables in Docker
• Helm / deployment parameters

The only workaround is to manually override the NGINX configuration inside the container.

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Proposed improvement

Expose an environment variable (or equivalent configuration mechanism) in the Docker image to allow setting:

server_names_hash_bucket_size

Optionally also:

server_names_hash_max_size

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Example desired usage

docker run \
  -e NGINX_SERVER_NAMES_HASH_BUCKET_SIZE=128 \
  -e NGINX_SERVER_NAMES_HASH_MAX_SIZE=512 \
  lemonldap-ng

or in docker-compose:

environment:
  NGINX_SERVER_NAMES_HASH_BUCKET_SIZE: 128
  NGINX_SERVER_NAMES_HASH_MAX_SIZE: 512

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Suggested benefit

• Makes LemonLDAP-ng more robust in multi-domain deployments
• Avoids container startup failures in production
• Reduces need for custom image overrides
• Improves cloud/Kubernetes compatibility

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Additional context

This issue typically occurs in environments with:

• Long FQDNs (e.g. *.env.region.company.tld)
• Multiple virtual hosts in NGINX
• Multi-tenant authentication setups
• Reverse proxy architectures