# Storage block

This documentation is for
a previous
version of Cerbos. Choose 0.53.0 from the version picker at the top right or navigate to [https://docs.cerbos.dev](https://docs.cerbos.dev/) for the latest version.

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

## Blob driver

Cerbos policies can be stored in AWS S3, Google Cloud Storage, or any other S3-compatible storage systems such as [Minio](https://www.minio.io/).

### 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&hostname_immutable=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.

Credentials for accessing the storage buckets are retrieved from the environment. The method of specifying credentials in the environment vary by cloud provider and security configuration. Usually, it involves defining environment variables such as `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY` for S3 and `GOOGLE_APPLICATION_CREDENTIALS` for GCS. Refer to the relevant cloud provider documentation for more details.

- AWS: [https://docs.aws.amazon.com/sdk-for-go/api/aws/session/](https://docs.aws.amazon.com/sdk-for-go/api/aws/session/)

- Google: [https://cloud.google.com/docs/authentication/provide-credentials-adc](https://cloud.google.com/docs/authentication/provide-credentials-adc)

### AWS S3 example

```yaml
storage:
  driver: "blob"
  blob:
    bucket: "s3://my-bucket-name?region=us-east-2"
    prefix: policies
    workDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 15s
    downloadTimeout: 30s
    requestTimeout: 10s
```

### Google Cloud Storage example

```yaml
storage:
  driver: "blob"
  blob:
    bucket: "gs://my-bucket-name"
    workDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 10s
```

### Minio local container example

```yaml
storage:
  driver: "blob"
  blob:
    bucket: "s3://my-bucket-name?endpoint=localhost:9000&disableSSL=true&hostname_immutable=true&region=local"
    workDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 10s
```

## 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

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

### Dynamic fileset with change detection

```yaml
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.

Archived fileset using a Zip file

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

## 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 example

```yaml
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 example

```yaml
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}
```

### Remote git repository accessed over SSH example

```yaml
storage:
  driver: "git"
  git:
    protocol: ssh
    url: github.com:cerbos/policy-test.git
    branch: main
    subDir: policies
    checkoutDir: ${HOME}/tmp/cerbos/work
    updatePollInterval: 60s
    ssh:
      user: git
      privateKeyFile: ${HOME}/.ssh/id_rsa
```

## Hub driver

Connects the PDP to a Cerbos Hub deployment label. Whenever a policy change is detected, the Cerbos Hub CI/CD pipeline compiles, tests and pushes an optimized policy bundle to the PDP.

If you are new to Cerbos Hub, follow the [getting started guide](https://docs.cerbos.dev/cerbos-hub/getting-started).

## MySQL driver

The MySQL storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.45.1/configuration/server#admin-api).

### Using MySQL as a storage backend for Cerbos

```yaml
storage:
  driver: "mysql"
  mysql:
    dsn: "${MYSQL_USER}:${MYSQL_PASSWORD}@tcp(localhost:3306)/cerbos"
```

### Secure connections

```yaml
storage:
  driver: "mysql"
  mysql:
    dsn: "${MYSQL_USER}:${MYSQL_PASSWORD}@tcp(localhost:3306)/cerbos?tls=mysecuretls"
    tls:
      mysecuretls:
        caCert: /path/to/ca_certificate.crt
        cert: /path/to/certificate.crt
        key: /path/to/private.key
```

### Connection pool

```yaml
storage:
  driver: "mysql"
  mysql:
    dsn: "${MYSQL_USER}:${MYSQL_PASSWORD}@tcp(localhost:3306)/cerbos"
    connPool:
      maxLifeTime: 5m
      maxIdleTime: 3m
      maxOpen: 10
      maxIdle: 5
```

### Connection retries

```yaml
storage:
  driver: "mysql"
  mysql:
    dsn: "${MYSQL_USER}:${MYSQL_PASSWORD}@tcp(localhost:3306)/cerbos"
    connRetry:
      maxAttempts: 3
      initialInterval: 1s
      maxInterval: 5s
```

### Database object definitions

```sql
CREATE DATABASE IF NOT EXISTS cerbos CHARACTER SET utf8mb4;

USE cerbos;

CREATE TABLE IF NOT EXISTS policy (
    id BIGINT PRIMARY KEY,
    kind VARCHAR(128) NOT NULL,
    name VARCHAR(1024) NOT NULL,
    version VARCHAR(128) NOT NULL,
    scope VARCHAR(512),
    description TEXT,
    disabled BOOLEAN default false,
    definition BLOB);
```

## Overlay driver

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.

```yaml
storage:
  driver: "overlay"
  overlay:
    baseDriver: postgres
    fallbackDriver: disk
    fallbackErrorThreshold: 5 # number of errors that occur within the fallbackErrorWindow to trigger failover
    fallbackErrorWindow: 5s # the rolling window in which errors are aggregated
  disk:
    directory: policies
    watchForChanges: true
  postgres:
    url: "postgres://${PG_USER}:${PG_PASSWORD}@localhost:5432/postgres?sslmode=disable&search_path=cerbos"
```

## Postgres driver

The Postgres storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.45.1/configuration/server#admin-api).

### Using Postgres as a storage backend for Cerbos

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

### Connection pool

```yaml
storage:
  driver: "postgres"
  postgres:
    url: "postgres://${PG_USER}:${PG_PASSWORD}@localhost:5432/postgres?sslmode=disable&search_path=cerbos"
    connPool:
      maxLifeTime: 5m
      maxIdleTime: 3m
      maxOpen: 10
      maxIdle: 5
```

### Connection retries

```yaml
storage:
  driver: "postgres"
  postgres:
    url: "postgres://${PG_USER}:${PG_PASSWORD}@localhost:5432/postgres?sslmode=disable&search_path=cerbos"
    connRetry:
      maxAttempts: 3
      initialInterval: 1s
      maxInterval: 5s
```

## SQLite3 driver

The SQLite3 storage backend is one of the dynamic stores that supports adding or updating policies at runtime through the [Admin API](https://docs.cerbos.dev/cerbos/0.45.1/configuration/server#admin-api).

### In-memory ephemeral database example

```yaml
storage:
  driver: "sqlite3"
  sqlite3:
    dsn: "file::memory:?cache=shared"
```

### On-disk persistent database example

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