.env variables

Brume reads configuration from a .env file in the current working directory (or from the process environment if .env is absent). Two categories: secrets (mandatory) and connections (one source, one target).

Secrets

These two values are the “additional information” of GDPR Art. 4.5 — protect them at the same level as the source data.

Variable	Required	Description
BRUME_HMAC_SECRET	yes	Seeds FAKE, HASH, linked_columns. Any high-entropy string ≥ 32 chars.
BRUME_FPE_KEY	yes	Keys the FF1 cipher used by FPE_ID / FPE_UUID. Must be at least 16 characters.

Rotate carefully

Rotating these secrets breaks determinism: future runs produce different fakes for the same source values. If you have downstream systems that join on HASH-ed or FPE_*-encrypted columns, plan a coordinated cutover.

Source connection

The database Brume reads from. Use a read-only account.

Variable	Required	Description
BRUME_SOURCE_HOST	yes	Hostname or IP
BRUME_SOURCE_PORT	no	Port. Default 5432.
BRUME_SOURCE_DB	yes	Database name
BRUME_SOURCE_USER	yes	Username (read-only recommended)
BRUME_SOURCE_PASSWORD	yes	Password
BRUME_SOURCE_SSLMODE	no	disable · prefer · require · verify-full. Default prefer.

Target connection

Either a Postgres connection or a directory for .sql output. Set one block, not both.

Target = PostgreSQL database

Variable	Required	Description
BRUME_TARGET_HOST	yes	Hostname or IP
BRUME_TARGET_PORT	no	Port. Default 5432.
BRUME_TARGET_DB	yes	Database name
BRUME_TARGET_USER	yes	Username (must be able to CREATE and INSERT)
BRUME_TARGET_PASSWORD	yes	Password
BRUME_TARGET_SSLMODE	no	Same values as source.

Target = SQL file

Variable	Required	Description
BRUME_TARGET_FILE	yes	Path to the .sql file Brume will write
BRUME_TARGET_FILE_COMPRESS	no	gzip to compress on the fly. Default: uncompressed.

When BRUME_TARGET_FILE is set, the Postgres target variables are ignored.

Runtime options

Variable	Required	Default	Description
BRUME_FK_DEPTH_OVERRIDE	no	—	Overrides extraction.fk_depth from brume.yml. Useful in CI for quick smoke runs.
BRUME_PARALLELISM	no	4	Number of worker threads for transformation.
BRUME_LOG_FORMAT	no	pretty	pretty or json. --json flag overrides this.
BRUME_LOCALE	no	system	Locale for Datafaker (e.g. fr_FR, en_US, de_DE).

Example .env

# --- Secrets (protect at the level of the source data) ---
BRUME_HMAC_SECRET=8aZb4...kpR9   # ≥ 32 chars, high entropy
BRUME_FPE_KEY=AnotherSecret16ch  # ≥ 16 chars

# --- Source (read-only) ---
BRUME_SOURCE_HOST=db.prod.internal
BRUME_SOURCE_DB=app_production
BRUME_SOURCE_USER=brume_reader
BRUME_SOURCE_PASSWORD=...
BRUME_SOURCE_SSLMODE=require

# --- Target = local Postgres ---
BRUME_TARGET_HOST=localhost
BRUME_TARGET_DB=app_dev
BRUME_TARGET_USER=app
BRUME_TARGET_PASSWORD=...

# --- Options ---
BRUME_PARALLELISM=8
BRUME_LOCALE=fr_FR

Creating a read-only account on the source

Suggested minimal grants:

CREATE ROLE brume_reader WITH LOGIN PASSWORD '...';
GRANT CONNECT ON DATABASE app_production TO brume_reader;
GRANT USAGE ON SCHEMA public TO brume_reader;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO brume_reader;
ALTER DEFAULT PRIVILEGES IN SCHEMA public
  GRANT SELECT ON TABLES TO brume_reader;

Adjust the schema name if your tables live outside public.

Next

• CLI commands — how to drive Brume from the command line.
• Operations & troubleshooting — secret management, performance, common errors.