Experimental DNS server to act as a proxy_pass resolver for nginx to bounce your requests to depending on SQLite lookup data

Experimental Python based DNS server that lets you use SQLite as a nginx proxy_pass resolver that performs an SQLite query to decide where to resolve/pass proxy_pass the request to.

( Asks a SQLite DB what the real IP for a lookup should be and returns that so proxy_pass can use it )

Based on https://github.com/paulc/dnslib/blob/master/dnslib/fixedresolver.py

docker-compose up

Then

• http://127.0.0.1/google Lookup "google" in the SQLite then resolve to an IP that hopefully still works and proxy_pass you there
• http://127.0.0.1/test-container Fallback example, key doesnt exist so we fallback to using the existing defined docker hosts/containers

Configuration

All settings are environment variables:

Variable	Default	Description
DATABASE_URL	sqlite:////data.db	SQLAlchemy connection URL. Supports SQLite, MySQL, PostgreSQL.
SQL_QUERY	SELECT dest_addr FROM lookup WHERE name IS NOT NULL AND name LIKE :name	Query to resolve a name. Must use :name as the named parameter.
DNS_TTL	60	TTL (seconds) for DNS responses and cache entries.
CACHE_SIZE	512	Max number of cached entries (LRU eviction).
UPSTREAM_DNS	127.0.0.11	Fallback DNS server for names not found in the DB (Docker embedded DNS).
UPSTREAM_PORT	53	Port for the upstream DNS server.
LOOKUP_TIMEOUT	3.0	Timeout in seconds for upstream DNS queries.

Backend examples

# SQLite (default)
DATABASE_URL=sqlite+aiosqlite:////data.db

# MySQL
DATABASE_URL=mysql+asyncmy://user:pass@mysql-host/dbname

# PostgreSQL
DATABASE_URL=postgresql+asyncpg://user:pass@pg-host/dbname

Install the matching async driver via requirements.txt (see comments in that file).

See

• http://nginx.org/en/docs/http/ngx_http_core_module.html#resolver
• https://docs.sqlalchemy.org/en/20/core/engines.html#database-urls

Note

Use at own risk, may or may not scale, may or may not rename your dog and set your house on fire.