Add-on Environment Variables

When you attach an add-on, Watasu injects connection details into your app as config vars. This page lists them per add-on. Read these like any other config var (watasu config --app my-app), but don’t overwrite them — the add-on resets them on its next reconcile.

PostgreSQL

Variable	Purpose
`DATABASE_URL`	Full Postgres connection string
`PGHOST`	Hostname
`PGPORT`	Port
`PGDATABASE`	Database name
`PGUSER`	Username
`PGPASSWORD`	Password

DATABASE_URL is what most ORMs and frameworks read. The discrete PG* variables are for tools (psql, pg_dump) and code that builds connections programmatically.

Valkey

Variable	Purpose
`REDIS_URL`	Redis-protocol connection URL

The REDIS_URL name is intentional — Valkey speaks the Redis protocol, and existing libraries that look for REDIS_URL work unchanged.

Object Storage

Object storage exports a wide set of S3-compatible variables so that whichever name your SDK looks for, it finds:

Variable	Purpose
`S3_BUCKET`	Bucket name (legacy/short form)
`AWS_S3_BUCKET`	Bucket name (AWS-style)
`AWS_ACCESS_KEY_ID`	Credential ID
`AWS_SECRET_ACCESS_KEY`	Credential secret
`AWS_ENDPOINT_URL`	Endpoint (this isn’t AWS — it’s the Watasu-managed S3-compatible endpoint)
`AWS_ENDPOINT_URL_S3`	Same as above, S3-specific override
`AWS_REGION`	Region label expected by AWS SDKs
`AWS_DEFAULT_REGION`	Same value, alternate name some SDKs read
`AWS_S3_REGION`	Same value, S3-specific override
`AWS_S3_URL`	Convenience URL combining bucket + endpoint

Most SDKs (boto3, aws-sdk-*, rclone, minio, etc.) pick these up automatically.

ClickHouse

ClickHouse exports a connection URL plus discrete connection components. Use a standard ClickHouse client library; it’ll find what it needs.

Redpanda

Redpanda exports broker addresses and SASL credentials. Use any Kafka-compatible client library.

Aliases

When you attach an add-on with --as <ALIAS>, every variable that add-on would normally export gets prefixed with ALIAS_:

watasu addons:attach reporting-db --app my-app --as REPORTING

Now your app sees both:

DATABASE_URL — the original primary
REPORTING_DATABASE_URL — the new alias

This is how you give one app multiple databases of the same kind, and it’s how PostgreSQL CLI commands target a specific database (watasu pg:psql REPORTING_DATABASE_URL).