Configuration

This documentation is for a previous version of Cerbos. Choose 0.37.0 from the version picker at the top right or navigate to https://docs.cerbos.dev for the latest version.

The Cerbos server is configured with a YAML file, conventionally named .cerbos.yaml. Start the server by passing the configuration file using the --config flag. The values defined in the file can be overridden from the command-line by using the --set flag. The --set flag can be used multiple times. For example, to override server.httpListenAddr and engine.defaultPolicyVersion, the --set flag can be used as follows:

./cerbos server --config=/path/to/.cerbos.yaml --set=server.httpListenAddr=:3592 --set=engine.defaultPolicyVersion=staging
Config values can reference environment variables by enclosing them between ${}, for example ${HOME}. Defaults can be set using ${VAR:default}.

Minimal Configuration

At a minimum, Cerbos requires a storage driver to be configured. If no explicit configuration is provided using the --config flag, Cerbos defaults to a disk driver configured to look for policies in a directory named policies in the current working directory.

Default configuration
---
server:
  httpListenAddr: ":3592"
  grpcListenAddr: ":3593"

engine:
  defaultPolicyVersion: "default"

auxData:
  jwt:
    disableVerification: true

storage:
  driver: "disk"
  disk:
    directory: "${PWD}/policies"
    watchForChanges: true

Full Configuration

Cerbos has many configuration options that are either optional or has reasonable defaults built-in. The following section describes all user-configurable options and their defaults.

Cerbos configuration file
---
audit:
  accessLogsEnabled: false # AccessLogsEnabled defines whether access logging is enabled.
  backend: local # Backend states which backend to use for Audits.
  decisionLogFilters: # DecisionLogFilters define the filters to apply while producing decision logs.
    checkResources: # CheckResources defines the filters that apply to CheckResources calls.
      ignoreAllowAll: false # IgnoreAllowAll ignores responses that don't contain an EFFECT_DENY.
    planResources: # PlanResources defines the filters that apply to PlanResources calls.
      ignoreAll: false # IgnoreAll prevents any plan responses from being logged. Takes precedence over other filters.
      ignoreAlwaysAllow: false # IgnoreAlwaysAllow ignores ALWAYS_ALLOWED plans.
  decisionLogsEnabled: false # DecisionLogsEnabled defines whether logging of policy decisions is enabled.
  enabled: false # Enabled defines whether audit logging is enabled.
  excludeMetadataKeys: ['authorization'] # ExcludeMetadataKeys defines which gRPC request metadata keys should be excluded from the audit logs. Takes precedence over includeMetadataKeys.
  includeMetadataKeys: ['content-type'] # IncludeMetadataKeys defines which gRPC request metadata keys should be included in the audit logs.
  file:
    additionalPaths: [stdout] # AdditionalPaths to mirror the log output. Has performance implications. Use with caution.
    logRotation: # LogRotation settings (optional).
      maxFileAgeDays: 10 # MaxFileAgeDays sets the maximum age in days of old log files before they are deleted.
      maxFileCount: 10 # MaxFileCount sets the maximum number of files to retain.
      maxFileSizeMB: 100 # MaxFileSizeMB sets the maximum size of individual log files in megabytes.
    path: /path/to/file.log # Required. Path to the log file to use as output. The special values stdout and stderr can be used to write to stdout or stderr respectively.
  hub:
    advanced:
      bufferSize: 256
      flushInterval: 1s
      gcInterval: 60s
      maxBatchSize: 32
    retentionPeriod: 168h # How long to keep records for
    storagePath: /path/to/dir # Path to store the data
  kafka:
    ack: all # Ack mode for producing messages. Valid values are "none", "leader" or "all" (default). Idempotency is disabled when mode is not "all".
    authentication: # Authentication
      tls:
        caPath: /path/to/ca.crt # Required. CAPath is the path to the CA certificate.
        certPath: /path/to/tls.cert # CertPath is the path to the client certificate.
        insecureSkipVerify: true # InsecureSkipVerify controls whether the server's certificate chain and host name are verified. Default is false.
        keyPath: /path/to/tls.key # KeyPath is the path to the client key.
        reloadInterval: 5m # ReloadInterval is the interval at which the TLS certificates are reloaded. The default is 0 (no reload).
    brokers: ['localhost:9092'] # Required. Brokers list to seed the Kafka client.
    clientID: cerbos # ClientID reported in Kafka connections.
    closeTimeout: 30s # CloseTimeout sets how long when closing the client to wait for any remaining messages to be flushed.
    compression: ['snappy'] # Compression sets the compression algorithm to use in order of priority. Valid values are "none", "gzip", "snappy","lz4", "zstd". Default is ["snappy", "none"].
    encoding: json # Encoding format. Valid values are "json" (default) or "protobuf".
    maxBufferedRecords: 1000 # MaxBufferedRecords sets the maximum number of records the client should buffer in memory in async mode.
    produceSync: false # ProduceSync forces the client to produce messages to Kafka synchronously. This can have a significant impact on performance.
    topic: cerbos.audit.log # Required. Topic to write audit entries to.
  local:
    advanced:
      bufferSize: 256
      flushInterval: 1s
      gcInterval: 60s
      maxBatchSize: 32
    retentionPeriod: 168h # How long to keep records for
    storagePath: /path/to/dir # Path to store the data
auxData:
  jwt: # JWT holds the configuration for JWTs used as an auxiliary data source for the engine.
    acceptableTimeSkew: 2s # AcceptableTimeSkew sets the acceptable skew when checking exp and nbf claims.
    cacheSize: 256 # CacheSize sets the number of verified tokens cached in memory. Set to negative value to disable caching.
    disableVerification: false # DisableVerification disables JWT verification.
    keySets: # KeySets is the list of keysets to be used to verify tokens.
      -
        id: ks1 # Required. ID is the unique reference to this keyset.
        insecure: # Insecure options for relaxing security. Not recommended for production use. Use with caution.
          optionalAlg: false # OptionalAlg configures Cerbos to not require the alg field to be set in the key set.
          optionalKid: false # OptionalKid configures Cerbos to not require the kid field to be set in the key set.
        local: # Local defines a local keyset. Mutually exclusive with Remote.
          data: base64encodedJWK # Data is the encoded JWK data for this keyset. Mutually exclusive with File.
          file: /path/to/keys.jwk # File is the path to file containing JWK data. Mutually exclusive with Data.
          pem: true # PEM indicates that the data is PEM encoded.
        remote: # Remote defines a remote keyset. Mutually exclusive with Local.
          refreshInterval: 1h # RefreshInterval is the refresh interval for the keyset.
          url: https://domain.tld/.well-known/keys.jwks # Required. URL is the JWKS URL to fetch the keyset from.
compile:
  cacheDuration: 60s # CacheDuration is the duration to cache an entry.
  cacheSize: 1024 # CacheSize is the number of compiled policies to cache in memory.
engine:
  defaultPolicyVersion: "default" # DefaultPolicyVersion defines what version to assume if the request does not specify one.
  globals: {"environment": "staging"} # Globals are environment-specific variables to be made available to policy conditions.
  lenientScopeSearch: false # LenientScopeSearch configures the engine to ignore missing scopes and search upwards through the scope tree until it finds a usable policy.
hub:
  credentials: # Credentials holds Cerbos Hub client credentials.
    clientID: 92B0K05B6HOF # ClientID of the Cerbos Hub credential. Defaults to the value of the CERBOS_HUB_CLIENT_ID environment variable.
    clientSecret: ${CERBOS_HUB_CLIENT_SECRET} # ClientSecret of the Cerbos Hub credential. Defaults to the value of the CERBOS_HUB_CLIENT_SECRET environment variable.
    pdpID: crb-004 # PDPID is the unique identifier for this Cerbos instance. Defaults to the value of the CERBOS_HUB_PDP_ID environment variable.
    workspaceSecret: ${CERBOS_HUB_WORKSPACE_SECRET} # WorkspaceSecret used to decrypt the bundles. Defaults to the value of the CERBOS_HUB_WORKSPACE_SECRET environment variable.
schema:
  cacheSize: 1024 # CacheSize defines the number of schemas to cache in memory.
  enforcement: reject # Enforcement defines level of the validations. Possible values are none, warn, reject.
server:
  apiExplorerEnabled: true # APIExplorerEnabled defines whether the API explorer UI is enabled.
  adminAPI: # AdminAPI defines the admin API configuration.
    adminCredentials: # AdminCredentials defines the admin user credentials.
      passwordHash: JDJ5JDEwJEdEOVFzZDE2VVhoVkR0N2VkUFBVM09nalc0QnNZaC9xc2E4bS9mcUJJcEZXenp5OUpjMi91Cgo= # PasswordHash is the base64-encoded bcrypt hash of the password to use for authentication.
      username: cerbos # Username is the hardcoded username to use for authentication.
    enabled: true # Enabled defines whether the admin API is enabled.
  advanced: # Advanced server settings.
    grpc: # GRPC server settings.
      connectionTimeout: 60s # ConnectionTimeout sets the timeout for establishing a new connection.
      maxConcurrentStreams: 1024 # MaxConcurrentStreams sets the maximum concurrent streams per connection. Defaults to 1024. Set to 0 to allow the maximum possible number of streams.
      maxConnectionAge: 600s # MaxConnectionAge sets the maximum age of a connection.
      maxRecvMsgSizeBytes: 4194304 # MaxRecvMsgSizeBytes sets the maximum size of a single request message. Defaults to 4MiB. Affects performance and resource utilisation.
    http: # HTTP server settings.
      idleTimeout: 120s # IdleTimeout sets the keepalive timeout.
      readHeaderTimeout: 15s # ReadHeaderTimeout sets the timeout for reading request headers.
      readTimeout: 30s # ReadTimeout sets the timeout for reading a request.
      writeTimeout: 30s # WriteTimeout sets the timeout for writing a response.
  cors: # CORS defines the CORS configuration for the server.
    allowedHeaders: ['content-type'] # AllowedHeaders is the contents of the allowed-headers header.
    allowedOrigins: ['*'] # AllowedOrigins is the contents of the allowed-origins header.
    disabled: false # Disabled sets whether CORS is disabled.
    maxAge: 10s # MaxAge is the max age of the CORS preflight check.
  grpcListenAddr: ":3593" # Required. GRPCListenAddr is the dedicated GRPC address.
  httpListenAddr: ":3592" # Required. HTTPListenAddr is the dedicated HTTP address.
  logRequestPayloads: false # LogRequestPayloads defines whether the request payloads should be logged.
  metricsEnabled: true # MetricsEnabled defines whether the metrics endpoint is enabled.
  requestLimits: # RequestLimits defines the limits for requests.
    maxActionsPerResource: 50 # MaxActionsPerResource sets the maximum number of actions that could be checked for a resource in a single request.
    maxResourcesPerRequest: 50 # MaxResourcesPerBatch sets the maximum number of resources that could be sent in a single request.
  tls: # TLS defines the TLS configuration for the server.
    caCert: /path/to/CA_certificate # CACert is the path to the optional CA certificate for verifying client requests.
    cert: /path/to/certificate # Cert is the path to the TLS certificate file.
    key: /path/to/private_key # Key is the path to the TLS private key file.
  udsFileMode: 0o766 # UDSFileMode sets the file mode of the unix domain sockets created by the server.
storage:
  # This section is required. The field driver must be set to indicate which driver to use.
  driver: "disk" # Required. Driver defines which storage driver to use.
  blob:
    # This section is required only if storage.driver is blob.
    bucket: "s3://my-bucket-name?region=us-east-2" # Required. Bucket URL (Examples: s3://my-bucket?region=us-west-1 gs://my-bucket azblob://my-container).
    downloadTimeout: 30s # DownloadTimeout specifies the timeout for downloading from cloud storage.
    prefix: policies # Prefix specifies a subdirectory to download.
    requestTimeout: 10s # RequestTimeout specifies the timeout for an HTTP request.
    updatePollInterval: 15s # UpdatePollInterval specifies the interval to poll the cloud storage. Set to 0 to disable.
    workDir: ${HOME}/tmp/cerbos/work # WorkDir is the local path to check out policies to.
  bundle:
    # This section is required only if storage.driver is bundle.
    cacheSize: 1024 # CacheSize defines the number of policies to cache in memory.
    local: # Local holds configuration for local bundle source.
      bundlePath: /path/to/bundle.crbp # Required. BundlePath is the full path to the local bundle file.
      tempDir: ${TEMP} # TempDir is the directory to use for temporary files.
    remote: # Remote holds configuration for remote bundle source. Takes precedence over local if both are defined.
      bundleLabel: latest # Required. BundleLabel to fetch from the server.
      cacheDir: ${XDG_CACHE_DIR} # CacheDir is the directory to use for caching downloaded bundles.
      disableAutoUpdate: <DEFAULT_VALUE_NOT_SET> # DisableAutoUpdate sets whether new bundles should be automatically downloaded and applied.
      tempDir: ${TEMP} # TempDir is the directory to use for temporary files.
  disk:
    # This section is required only if storage.driver is disk.
    directory: pkg/test/testdata/store # Required. Directory is the path on disk where policies are stored.
    watchForChanges: false # Required. WatchForChanges enables watching the directory for changes.
  git:
    # This section is required only if storage.driver is git.
    branch: policies # Branch is the branch to checkout.
    checkoutDir: ${HOME}/tmp/cerbos/work # CheckoutDir is the local path to checkout the Git repo to.
    https: # HTTPS holds auth details for the HTTPS protocol.
      password: ${GITHUB_TOKEN} # The password (or token) to use for authentication.
      username: cerbos # The username to use for authentication.
    operationTimeout: 60s # OperationTimeout specifies the timeout for git operations.
    protocol: file # Required. Protocol is the Git protocol to use. Valid values are https, ssh, and file.
    ssh: # SSH holds auth details for the SSH protocol.
      password: pw # The password to the SSH private key.
      privateKeyFile: ${HOME}/.ssh/id_rsa # The path to the SSH private key file.
      user: git # The git user. Defaults to git.
    subDir: policies # SubDir is the path under the checked-out Git repo where the policies are stored.
    url: file://${HOME}/tmp/cerbos/policies # Required. URL is the URL to the Git repo.
    updatePollInterval: 60s # UpdatePollInterval specifies the interval to poll the Git repository for changes. Set to 0 to disable.
  mysql:
    # This section is required only if storage.driver is mysql.
    connPool:
      maxLifeTime: 60m
      maxIdleTime: 45s
      maxOpen: 4
      maxIdle: 1
    connRetry:
      maxAttempts: 3
      initialInterval: 0.5s
      maxInterval: 60s
    dsn: "user:password@tcp(localhost:3306)/db?interpolateParams=true" # Required. DSN is the data source connection string.
    serverPubKey:
      mykey: testdata/server_public_key.pem
    skipSchemaCheck: false # SkipSchemaCheck skips checking for required database tables on startup.
    tls:
      mytls:
        cert: /path/to/certificate
        key: /path/to/private_key
        caCert: /path/to/CA_certificate
  overlay:
    # This section is required only if storage.driver is overlay.
    baseDriver: blob # Required. BaseDriver is the default storage driver
    fallbackDriver: disk # Required. FallbackDriver is the secondary or fallback storage driver
    fallbackErrorThreshold: 5 # FallbackErrorThreshold is the max number of errors we allow within the fallbackErrorWindow period
    fallbackErrorWindow: 5m # FallbackErrorWindow is the cyclic period within which we aggregate failures
  postgres:
    # This section is required only if storage.driver is postgres.
    connPool:
      maxLifeTime: 60m
      maxIdleTime: 45s
      maxOpen: 4
      maxIdle: 1
    connRetry:
      maxAttempts: 3
      initialInterval: 0.5s
      maxInterval: 60s
    skipSchemaCheck: false # SkipSchemaCheck skips checking for required database tables on startup.
    url: "postgres://user:password@localhost:port/db" # Required. URL is the Postgres connection URL. See https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING
  sqlite3:
    # This section is required only if storage.driver is sqlite3.
    dsn: ":memory:?_fk=true" # Required. Data source name
  sqlserver:
    # This section is required only if storage.driver is sqlserver.
    connPool:
      maxLifeTime: 60m
      maxIdleTime: 45s
      maxOpen: 4
      maxIdle: 1
    connRetry:
      maxAttempts: 3
      initialInterval: 0.5s
      maxInterval: 60s
    skipSchemaCheck: false # SkipSchemaCheck skips checking for required database tables on startup.
    url: "sqlserver://username:password@host/instance?param1=value&param2=value" # Required. URL is the SQL Server connection URL. See https://github.com/microsoft/go-mssqldb#connection-parameters-and-dsn.
telemetry:
  disabled: false # Disabled sets whether telemetry collection is disabled or not.
  reportInterval: 1h # ReportInterval is the interval between telemetry pings.
  stateDir: ${HOME}/.config/cerbos # StateDir is used to persist state to avoid repeatedly sending the data over and over again.