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Configuration

DoubleDino is configured with environment variables. No configuration file is required.

Core​

These settings define the DoubleDino instance.

DD_MODE​

Operating mode.

Required: Yes

Values: proxy, clone

export DD_MODE=proxy

DD_SOURCE_URL​

Connection string for the source data.

Required: Yes

export DD_SOURCE_URL='postgres://postgres:password@localhost:5432/database'

The format depends on the data source.

Supported sources:

  • PostgreSQL
  • MySQL
  • MariaDB
  • MongoDB
  • Redis
  • Log files

See the documentation for the individual data sources.

DD_SECRET_KEY​

Secret key used for deterministic transformation.

Required: Yes

export DD_SECRET_KEY='your-secret-key'

The same input produces the same transformed output when the same key is used. This allows relationships and repeated values to remain consistent.

Changing the key produces different transformed values.

DD_AUTH_KEY​

API authentication key.

Required: Proxy mode

export DD_AUTH_KEY='your-api-key'

Clients must provide the key in the x-api-key header.

Keep both DD_SECRET_KEY and DD_AUTH_KEY private.

Clone mode​

These settings apply only when DD_MODE=clone.

DD_DEST_URL​

Connection string for the destination.

Required: Yes in Clone mode

export DD_DEST_URL='postgres://postgres:password@localhost:5432/development'

The source and destination must use the same data source type.

PostgreSQL → PostgreSQL
MySQL      → MySQL
MariaDB    → MariaDB
MongoDB    → MongoDB

Proxy mode​

These settings apply only when DD_MODE=proxy.

DD_HTTP_PORT​

HTTP port used by the API.

Default: 8080

export DD_HTTP_PORT=9000

DD_MAX_REQUEST​

Maximum requests allowed per IP address.

Default: 10

export DD_MAX_REQUEST=100

This limits excessive requests to the Proxy API.

Transformation​

These settings control how values are transformed.

DD_SUPPORTED_CHARSETS​

Character sets available to the transformation engine.

Default: english,latin

export DD_SUPPORTED_CHARSETS=english,latin

DD_PRESERVED_EXPRESSIONS​

Expressions that should remain unchanged during transformation.

export DD_PRESERVED_EXPRESSIONS="shipping updates,refund,billing desk"

For example:

Order delayed due to shipping updates

can become:

Ehfwfzjx shipping updates niglwzp

Use preserved expressions carefully because they remain visible.

DD_EXCLUDE_KEYS​

Keys whose values should not be transformed.

export DD_EXCLUDE_KEYS=id,user_id,customer_id

For example:

{
  "id": 123,
  "email": "[email protected]"
}

becomes:

{
  "id": 123,
  "email": "[email protected]"
}

DD_ALLOW_DYNAMIC_EXPRESSIONS​

Allows clients to provide additional preserved expressions per request.

Default: false

export DD_ALLOW_DYNAMIC_EXPRESSIONS=true

When enabled, clients can use the x-preserve-expressions header:

-H "x-preserve-expressions: tracking metadata"

Only enable this when clients are trusted. Dynamically preserved expressions can expose values that would otherwise be transformed.

Logging​

DoubleDino writes logs to standard output and standard error.

DD_LOG_FORMAT​

Log output format.

Default: json

Values: json, text

export DD_LOG_FORMAT=json

DD_LOG_LEVEL​

Controls the amount of information written to the logs.

Values: info, audit, DPI

export DD_LOG_LEVEL=audit
  • info - operational information.
  • audit - operational and security-related events.
  • DPI - detailed request-level inspection.

DPI logging can contain detailed request information. Enable it only when required.

Environment example​

A minimal Proxy configuration:

export DD_MODE=proxy
export DD_SOURCE_URL='postgres://postgres:password@localhost:5432/production'
export DD_SECRET_KEY='your-secret-key'
export DD_AUTH_KEY='your-api-key'

./doubledino

A minimal Clone configuration:

export DD_MODE=clone
export DD_SOURCE_URL='postgres://postgres:password@localhost:5432/production'
export DD_DEST_URL='postgres://postgres:password@localhost:5432/development'
export DD_SECRET_KEY='your-secret-key'

./doubledino