Storage block

Cerbos supports multiple backends for storing policies. Which storage driver to use is defined by the driver setting.

Disk driver

The disk driver is a way to serve the policies from a directory on the filesystem. Any .yaml, .yml or .json files in the directory tree rooted at the given path will be read and parsed as policies.

Static fileset with no change detection

storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies

Dynamic fileset with change detection

storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies
    watchForChanges: true

Archive Files

Alternatively, you can opt to archive and/or compress your policies directory into a Zip (.zip), Tar (.tar) or Gzip file (.tgz or .tar.gz). The archive is assumed to be laid out like a standard policy directory. It must contain no non-policy YAML files.

You specify the file in your config like so:

Archived fileset using a Zip file

storage:
  driver: disk
  disk:
    directory: /etc/cerbos/policies.zip

Blob driver

Cerbos policies can be stored in AWS S3, Google Cloud Storage, or any other S3-compatible storage systems such as Minio.

Configuration keys

• bucket: Required. A URL specifying the service (e.g. S3, GCS), the storage bucket and any other configuration parameters required by the provider.

• AWS S3: s3://my-bucket?region=us-west-1. Must specify region in the URL.

  • Google Cloud Storage: gs://my-bucket
  • S3-compatible (e.g. Minio): s3://my-bucket?endpoint=my.minio.local:8080&disableSSL=true&s3ForcePathStyle=true&region=local. Must specify region in the URL.

• prefix: Optional. Look for policies only under this key prefix.

• workDir: Optional. Path to the local directory to download the policies to. Defaults to the system cache directory if not specified.

• updatePollInterval: Optional. How frequently the blob store should be checked to discover new or updated policies. Defaults to 0 — which disables polling.

• requestTimeout: Optional. HTTP request timeout. It takes an HTTP request to download a policy file. Defaults to 5s.

• downloadTimeout: Optional. Timeout to download all policies from the storage provider. Must be greater than the requestTimeout. Defaults to 60s.

...

Git driver

Git is the preferred method of storing Cerbos policies. The server is smart enough to detect when new commits are made to the git repository and refresh its state based on the changes.

Local git repository

storage:
  driver: "git"
  git:
    protocol: file
    url: file://${HOME}/tmp/cerbos/policies
    checkoutDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 10s

Remote git repository accessed over HTTPS

storage:
  driver: "git"
  git:
    protocol: https
    url: https://github.com/cerbos/policy-test.git
    branch: main
    subDir: policies
    checkoutDir: ${HOME}/tmp/work/policies
    updatePollInterval: 60s
    operationTimeout: 30s
    https:
      username: cerbos
      password: ${GITHUB_TOKEN}

SQLite3 Driver

The SQLite3 storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the Admin API.

In-memory ephemeral database

storage:
  driver: "sqlite3"
  sqlite3:
    dsn: ":memory:"

On-disk persistent database

storage:
  driver: "sqlite3"
  sqlite3:
    dsn: "file:/tmp/cerbos.sqlite?mode=rwc&cache=shared&_fk=true"

Postgres Driver

The Postgres storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the Admin API.

Using Postgres as a storage backend for Cerbos

storage:
  driver: "postgres"
  postgres:
    url: "postgres://${PG_USER}:${PG_PASSWORD}@localhost:5432/postgres?sslmode=disable&search_path=cerbos"

...

Microsoft SQL Server Driver

The SQL Server storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the Admin API.

Using SQL Server as a storage backend for Cerbos

storage:
  driver: "sqlserver"
  sqlserver:
    url: "sqlserver://${SQL_SERVER_USERNAME}:${SQL_SERVER_PASSWORD}@host/instance?database=cerbos&param1=value&param2=value"

Connection pool

Cerbos uses a connection pool when connecting to a database. You can configure the connection pool settings by adding a connPool section to the driver configuration.

Available options are:

• maxLifeTime
• maxIdleTime
• maxOpen
• maxIdle

storage:
  driver: "sqlserver"
  sqlserver:
    url: "sqlserver://${SQL_SERVER_USERNAME}:${SQL_SERVER_PASSWORD}@host/instance?database=cerbos&param1=value&param2=value"
    connPool:
      maxLifeTime: 5m
      maxIdleTime: 3m
      maxOpen: 10
      maxIdle: 5

Redundancy

You can provide redundancy by configuring an overlay driver, which wraps a base and a fallback driver. Under normal operation, the base driver will be targeted as usual. However, if the driver consistently errors, the PDP will start targeting the fallback driver instead.