Environment variables

This page lists every environment variable MicroB2B reads. They hold what MicroB2B needs before it can open its database. Everything else is stored in the database and changed in the web UI or the REST API.

Some settings are not environment variables:

Where message contents are stored, and other global settings, are in System > Settings. See settings.
Ports, directories and retry settings of receivers, senders and other parts are in their own configuration in the web UI.

Variables take effect when MicroB2B starts. After a change, restart MicroB2B.

For a key, you can give the value itself or, with the _FILE variant, the path of a file that holds it. Give one of the two, never both.

Required

Variable	What it does	Default
`PUBLIC_URL`	The address users reach MicroB2B at, such as `https://b2b.example.com`. HTTPS, no path. `http` only for `localhost`, `127.0.0.1` and `::1`	none, required
`SESSION_KEY`, `SESSION_KEY_FILE`	Key of the sign-in cookies. Base64 or hex of at least 32 random bytes	none, required
`SECRETS_KEY`, `SECRETS_KEY_FILE`	Master key of stored secrets and private keys. Base64 or hex of exactly 32 random bytes	none, required

See required settings for how to generate them.

Sign-in

Variable	What it does	Default
`SESSION_TTL`	How long a sign-in lasts, from `5m` to `72h`	`8h`

Database

Variable	What it does	Default
`DB_TYPE`	`sqlite3` or `postgres`	`sqlite3`
`DB_URL`	Where the database is	`file:microb2b.db`
`DB_MAX_OPEN_CONNS`	PostgreSQL only: most open connections. `0` means no limit	`25`
`DB_MAX_IDLE_CONNS`	PostgreSQL only: idle connections kept. At most `DB_MAX_OPEN_CONNS`	`10`
`DB_CONN_MAX_LIFETIME`	PostgreSQL only: close a connection after this age. `0` means never	`30m`
`DB_CONN_MAX_IDLE_TIME`	PostgreSQL only: close a connection idle this long. `0` means never	`5m`
`BUNDEBUG`	`1` or `2` logs every SQL statement. Needs `LOG_LEVEL=debug`. Failed statements are always logged	not set

See database.

Web server

Variable	What it does	Default
`HTTP_PORT`	Port of the web UI and REST API, on every interface	`8080`
`ALLOWED_ORIGINS`	Other websites whose pages may call the REST API from a browser. Comma-separated, or `*` for all	empty: none

See reverse proxy.

Secrets and audit log

Variable	What it does	Default
`SECRETS_PREVIOUS_KEYS`, `SECRETS_PREVIOUS_KEYS_FILE`	Earlier master keys while you replace `SECRETS_KEY`. Separated by commas, spaces or new lines	not set
`AUDIT_KEY`, `AUDIT_KEY_FILE`	Makes the audit log tamper-evident. Base64 or hex of at least 32 random bytes	not set: no hashes

MicroB2B refuses to start with an unknown variable that starts with SECRETS_ or AUDIT_. That catches typing errors. See secrets and audit log.

S3 payload storage

Variable	What it does	Default
`AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY`	Credentials for S3 payload storage	not set

MicroB2B finds S3 credentials the way every AWS tool does. Instead of these variables, you can use the AWS credentials file or a role of the server. The bucket itself is a setting in System > Settings. See payload storage.

Logging

Variable	What it does	Default
`LOG_LEVEL`	`debug`, `info`, `warn` or `error`. Anything else means `info`	`info`
`LOG_STREAM_LEVEL`	Lowest level on the Logs page and in the OpenTelemetry export. Cannot be below `LOG_LEVEL`	`info`

OpenTelemetry

Variable	What it does	Default
`OTEL_ENABLED`	`true` sends traces, metrics and logs	`false`
`OTEL_EXPORTER_OTLP_ENDPOINT`	Where to send them, `host:port`, over gRPC with TLS	`localhost:4317`
`OTEL_EXPORTER_OTLP_INSECURE`	`true` sends without TLS	`false`
`OTEL_EXPORTER_OTLP_HEADERS`	Headers for every export, `key=value,key2=value2`. For Uptrace: `uptrace-dsn=<DSN>`	not set
`OTEL_SERVICE_NAME`	Name MicroB2B reports itself as	`microb2b`
`OTEL_SERVICE_VERSION`	Version it reports	the program’s version

See monitoring.

Which commands read what

microb2b standalone reads all of the above.
microb2b users and microb2b service-accounts read the database variables. microb2b users also reads PUBLIC_URL, to print whole setup links.
microb2b secrets reads the database variables and the SECRETS_* variables.
microb2b audit reads the database variables and the AUDIT_* variables.

See the command line.

Command line