Configuration

This page defines the format of OPA configuration files. Fields marked as required must be specified if the parent is defined. For example, when the configuration contains a status key, the status.service field must be defined.

The configuration file path is specified with the -c or --config-file command line argument:

opa run -s -c config.yaml

The file can be either JSON or YAML format.

Example

services:
  acmecorp:
    url: https://example.com/control-plane-api/v1
    response_header_timeout_seconds: 5
    credentials:
      bearer:
        token: "bGFza2RqZmxha3NkamZsa2Fqc2Rsa2ZqYWtsc2RqZmtramRmYWxkc2tm"

labels:
  app: myapp
  region: west
  environment: production

bundles:
  authz:
    service: acmecorp
    resource: bundles/http/example/authz.tar.gz
    persist: true
    polling:
      min_delay_seconds: 60
      max_delay_seconds: 120
    signing:
      keyid: global_key
      scope: write

decision_logs:
  service: acmecorp
  reporting:
    min_delay_seconds: 300
    max_delay_seconds: 600

status:
  service: acmecorp

default_decision: /http/example/authz/allow

keys:
  global_key:
    algorithm: RS256
    key: <PEM_encoded_public_key>
    scope: read

caching:
  inter_query_builtin_cache:
    max_size_bytes: 10000000

Environment Variable Substitution

Only supported with the OPA runtime (opa run).

Environment variables referenced with the ${...} notation within the configuration will be replaced with the value of the environment variable.

Example using BASE_URL and BEARER_TOKEN environment variables:

services:
  acmecorp:
    url: ${BASE_URL}
    credentials:
      bearer:
        token: "${BEARER_TOKEN}"

discovery:
  name: example
  resource: /configuration/example/discovery

The environment variables BASE_URL and BEARER_TOKEN will be substituted in when the config file is loaded by the OPA runtime.

If the variable is undefined then an empty string ("") is substituted. It will not raise an error.

CLI Runtime Overrides

Only supported with the OPA runtime (opa run).

Using opa run there are CLI options to explicitly set config values. These will override any values set in the config file.

There are two options to use: --set and --set-file

Both options take in a key=value format where the key is a selector for the yaml config structure, for example: decision_logs.reporting.min_delay_seconds=300 is equivalent to JSON {"decision_logs": {"reporting": {"min_delay_seconds": 300}}}. Multiple values can be specified with comma separators (key1=value,key2=value2,..). Or with additional --set parameters.

Example using several different options:

opa run \
  --set "default_decision=/http/example/authz/allow" \
  --set "services.acmecorp.url=https://test-env/control-plane-api/v1" \
  --set "services.acmecorp.credentials.bearer.token=\${TOKEN}"
  --set "labels.app=myapp,labels.region=west"

This is equivalent to a YAML config file that looks like:

services:
  acmecorp:
    url: https://test-env/control-plane-api/v1
    credentials:
      bearer:
        token: ${TOKEN}

labels:
  app: myapp
  region: west

default_decision: /http/example/authz/allow

The --set-file option is expecting a file path for the value. This allows keeping secrets in files and loading them into the config at run time. For Example:

With a file /var/run/secrets/bearer_token.txt that has contents:

bGFza2RqZmxha3NkamZsa2Fqc2Rsa2ZqYWtsc2RqZmtramRmYWxkc2tm

Then using the --set-file flag for OPA

opa run --set-file "services.acmecorp.credentials.bearer.token=/var/run/secrets/bearer_token.txt"

It will read the contents of the file and set the config value with the token.

Override Limitations
Lists

If using arrays/lists in the configuration the --set and --set-file overrides will not be able to patch sub-objects of the list. They will overwrite the entire index with the new object.

For example, a config.yaml file with contents:

services:
  - name: acmecorp
    url: https://test-env/control-plane-api/v1
    credentials:
      bearer:
        token: ""

Used with overrides:

opa run \
  --config-file config.yaml
  --set-file "services[0].credentials.bearer.token=/var/run/secrets/bearer_token.txt"

Will result in configuration like:

services:
  - credentials:
      bearer:
        token: bGFza2RqZmxha3NkamZsa2Fqc2Rsa2ZqYWtsc2RqZmtramRmYWxkc2tm

Because the entire 0 index was overwritten.

It is highly recommended to use objects/maps instead of lists for configuration for this reason.

Empty objects

If you need to set an empty object with the CLI overrides, for example with plugin configuration like:

decision_logs:
  plugin: my_plugin

plugins:
  my_plugin:
    # empty

You can do this by setting the value with null. For example:

opa run --set "decision_logs.plugin=my_plugin" --set "plugins.my_plugin=null"
Keys with Special Characters

If you have a key which contains a special character (., =, etc), like opa.example.com, and want to use the --set or --set-file options you will need to escape the character with a backslash (\).

For example a config section like:

services:
  opa.example.com:
    url: https://opa.example.com

Could be specified with something like:

--set services.opa\.example\.com.url=https://opa.example.com

Note that when using it in a shell you may need to put it in quotes or escape the \ character too. For example:

--set services."opa\.example\.com".url=https://opa.example.com

or

--set services.opa\\.example\\.com.url=https://opa.example.com

Where the end result passed into OPA still has the \. preserved.

Services

Services represent endpoints that implement one or more control plane APIs such as the Bundle or Status APIs. OPA configuration files may contain multiple services.

FieldTypeRequiredDescription
services[_].namestringYesUnique name for the service. Referred to by plugins.
services[_].urlstringYesBase URL to contact the service with.
services[_].response_header_timeout_secondsint64No (default: 10)Amount of time to wait for a server’s response headers after fully writing the request. This time does not include the time to read the response body.
services[_].headersobjectNoHTTP headers to include in requests to the service.
services[_].allow_insecure_tlsboolNoAllow insecure TLS.

Each service may optionally specify a credential mechanism by which OPA will authenticate itself to the service.

Bearer Token

OPA will authenticate using the specified bearer token and schema; to enable bearer token authentication, either the token or the path to the token must be specified. If the latter is provided, on each request OPA will re-read the token from the file and use that token for authentication.

The schema is optional and will default to Bearer if unspecified.

FieldTypeRequiredDescription
services[_].credentials.bearer.tokenstringYesEnables token-based authentication and supplies the bearer token to authenticate with.
services[_].credentials.bearer.token_pathstringYesEnables token-based authentication and supplies the path to the bearer token to authenticate with.
services[_].credentials.bearer.schemestringNoBearer token scheme to specify.

Client TLS Certificate

OPA will present the specified TLS certificate to authenticate. The paths to the client certificate and the private key are required; the passphrase for the private key is only required if the private key is encrypted.

FieldTypeRequiredDescription
services[_].credentials.client_tls.certstringYesThe path to the client certificate to authenticate with.
services[_].credentials.client_tls.private_keystringYesThe path to the private key of the client certificate.
services[_].credentials.client_tls.private_key_passphrasestringNoThe passphrase to use for the private key.

OAuth2 Client Credentials

OPA will authenticate using a bearer token obtained through the OAuth2 client credentials flow. Following successful authentication at the token endpoint the returned token will be cached for subsequent requests for the duration of its lifetime. Note that as per the OAuth2 standard, only the HTTPS scheme is supported for the token endpoint URL.

FieldTypeRequiredDescription
services[_].credentials.oauth2.token_urlstringYesURL pointing to the token endpoint at the OAuth2 authorization server.
services[_].credentials.oauth2.client_idstringYesThe client ID to use for authentication.
services[_].credentials.oauth2.client_secretstringYesThe client secret to use for authentication.
services[_].credentials.oauth2.scopes[]stringNoOptional list of scopes to request for the token.

OAuth2 Client Credentials JWT authentication

OPA will authenticate using a bearer token obtained through the OAuth2 client credentials flow. Rather than providing a client secret along with the request for an access token, the client asserts its identity in the form of a signed JWT. Following successful authentication at the token endpoint the returned token will be cached for subsequent requests for the duration of its lifetime. Note that as per the OAuth2 standard, only the HTTPS scheme is supported for the token endpoint URL.

FieldTypeRequiredDescription
services[_].credentials.oauth2.token_urlstringYesURL pointing to the token endpoint at the OAuth2 authorization server.
services[_].credentials.oauth2.grant_typestringNoDefaults to client_credentials.
services[_].credentials.oauth2.client_idstringNoThe client ID to use for authentication.
services[_].credentials.oauth2.signing_keystringYesReference to private key used for signing the JWT.
services[_].credentials.oauth2.additional_claimsmapNoMap of claims to include in the JWT (see notes below)
services[_].credentials.oauth2.include_jti_claimboolNoInclude a uniquely generated jti claim in any issued JWT
services[_].credentials.oauth2.scopes[]stringNoOptional list of scopes to request for the token.

Two claims will always be included in the issued JWT: iat and exp. Any other claims will be populated from the additional_claims map.

Example

Using the client credentials grant type with JWT client authentication replacing client secret as the credential used at the token endpoint.

services:
  remote:
    url: ${BUNDLE_SERVICE_URL}
    credentials:
      oauth2:
        grant_type: client_credentials
        client_id: opa-client
        signing_key: jwt_signing_key # references the key in `keys` below
        include_jti_claim: true
        scopes:
        - read
        - write
        additional_claims:
          sub: opa-client
          iss: opa-${POD_NAME}

bundles:
  authz:
    service: remote
    resource: bundles/http/example/authz.tar.gz

keys:
  jwt_signing_key:
    algorithm: ES512
    private_key: ${BUNDLE_SERVICE_SIGNING_KEY}

OAuth2 JWT Bearer Grant Type

OPA will authenticate using a bearer token obtained through the OAuth2 JWT authorization grant flow. Rather than providing a client secret along with the request for an access token, the client asserts its identity in the form of a signed JWT. Following successful authentication at the token endpoint the returned token will be cached for subsequent requests for the duration of its lifetime. Note that as per the OAuth2 standard, only the HTTPS scheme is supported for the token endpoint URL.

FieldTypeRequiredDescription
services[_].credentials.oauth2.token_urlstringYesURL pointing to the token endpoint at the OAuth2 authorization server.
services[_].credentials.oauth2.grant_typestringNoMust be set to jwt_bearer for JWT bearer grant type. Defaults to client_credentials.
services[_].credentials.oauth2.signing_keystringYesReference to private key used for signing the JWT.
services[_].credentials.oauth2.additional_claimsmapNoMap of claims to include in the JWT (see notes below)
services[_].credentials.oauth2.include_jti_claimboolNoInclude a uniquely generated jti claim in any issued JWT
services[_].credentials.oauth2.scopes[]stringNoOptional list of scopes to request for the token.

Two claims will always be included in the issued JWT: iat and exp. Any other claims will be populated from the additional_claims map.

Example

Using a Google Cloud Storage bucket as a bundle service backend from outside the cloud account (for access from inside the account, see the GCP Metadata Token section).

services:
  gcp:
    url: ${BUNDLE_SERVICE_URL}
    credentials:
      oauth2:
        grant_type: jwt_bearer
        signing_key: jwt_signing_key # references the key in `keys` below
        scopes:
        - https://www.googleapis.com/auth/devstorage.read_only
        additional_claims:
          aud: https://oauth2.googleapis.com/token
          iss: opa-client@my-account.iam.gserviceaccount.com

bundles:
  authz:
    service: gcp
    resource: bundles/http/example/authz.tar.gz

keys:
  jwt_signing_key:
    algorithm: RS256
    private_key: ${BUNDLE_SERVICE_SIGNING_KEY}

AWS Signature

OPA will authenticate with an AWS4 HMAC signature. Two methods of obtaining the necessary credentials are available; exactly one must be specified to use the AWS signature authentication method.

Using Static Environment Credentials

If specifying environment_credentials, OPA will expect to find environment variables for AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_REGION, in accordance with the convention used by the AWS CLI.

Please note that if you are using temporary IAM credentials (e.g. assumed IAM role credentials) you have to provide additional AWS_SESSION_TOKEN or AWS_SECURITY_TOKEN environment variable.

FieldTypeRequiredDescription
services[_].credentials.s3_signing.environment_credentials{}YesEnables AWS signing using environment variables to source the configuration and credentials
Using EC2 Metadata Credentials

If specifying metadata_credentials, OPA will use the AWS metadata services for EC2 or ECS to obtain the necessary credentials when running within a supported virtual machine/container.

To use the EC2 metadata service, the IAM role to use and the AWS region for the resource must both be specified as iam_role and aws_region respectively.

To use the ECS metadata service, specify only the AWS region for the resource as aws_region. ECS containers have at most one associated IAM role.

N.B. Providing a value for iam_role will cause OPA to use the EC2 metadata service even if running inside an ECS container. This may result in unexpected problems if, for example, there is no route to the EC2 metadata service from inside the container or if the IAM role is only available within the container and not from the hosting EC2 instance.

FieldTypeRequiredDescription
services[_].credentials.s3_signing.metadata_credentials.aws_regionstringNoThe AWS region to use for the AWS signing service credential method. If unset, the AWS_REGION environment variable must be set
services[_].credentials.s3_signing.metadata_credentials.iam_rolestringNoThe IAM role to use for the AWS signing service credential method
Using EKS IAM Roles for Service Account (Web Identity) Credentials

If specifying web_identity_credentials, OPA will expect to find environment variables for AWS_ROLE_ARN and AWS_WEB_IDENTITY_TOKEN_FILE, in accordance with the convention used by the AWS EKS IAM Roles for Service Accounts.

FieldTypeRequiredDescription
services[_].credentials.s3_signing.web_identity_credentials.aws_regionstringYesThe AWS region to use for the sts regional endpoint. Uses the global endpoint by default
services[_].credentials.s3_signing.web_identity_credentials.session_namestringNoThe session name used to identify the assumed role session. Default: open-policy-agent

Services can be defined as an array or object. When defined as an object, the object keys override the services[_].name fields. For example:

services:
  s1:
    url: https://s1/example/
  s2:
    url: https://s2/

Is equivalent to

services:
  - name: s1
    url: https://s1/example/
  - name: s2
    url: https://s2/

GCP Metadata Token

OPA will authenticate with a GCP access token or identity token fetched from the Compute Metadata Server. When one or more scopes is provided an access token is fetched. When a non-empty audience is provided an identity token is fetched. An audience or scopes array is required.

When authenticating to native GCP services such as Google Cloud Storage an access token should be used with the appropriate set of scopes required by the target resource. When authenticating to a third party application such as an application hosted on Google Cloud Run an identity token should be used.

FieldTypeRequiredDescription
services[_].credentials.gcp_metadata.audiencestringNoThe audience to use when fetching identity tokens.
services[_].credentials.gcp_metadata.endpointstringNoThe metadata endpoint to use.
services[_].credentials.gcp_metadata.scopesarrayNoThe set of scopes to use when fetching access token.
services[_].credentials.gcp_metadata.access_token_pathstringNoThe access token metadata path to use.
services[_].credentials.gcp_metadata.id_token_pathstringNoThe identity token metadata path to use.
Example

Using a Cloud Run service as a bundle service backend.

services:
  cloudrun:
    url: ${BUNDLE_SERVICE_URL}
    response_header_timeout_seconds: 5
    credentials:
      gcp_metadata:
        audience: ${BUNDLE_SERVICE_URL}

bundles:
  authz:
    service: cloudrun
    resource: bundles/http/example/authz.tar.gz
    persist: true
    polling:
      min_delay_seconds: 60
      max_delay_seconds: 120

Using Google Cloud Storage as a bundle service backend.

services:
  gcs:
    url: https://storage.googleapis.com/storage/v1/b/${BUCKET_NAME}/o
    response_header_timeout_seconds: 5
    credentials:
      gcp_metadata:
        scopes:
          - "https://www.googleapis.com/auth/devstorage.read_only"

bundles:
  authz:
    service: gcs
    resource: 'bundle.tar.gz?alt=media'
    persist: true
    polling:
      min_delay_seconds: 60
      max_delay_seconds: 120

Custom Plugin

If none of the existing credential options work for a service, OPA can authenticate using a custom plugin, enabling support for any authentication scheme.

FieldTypeRequiredDescription
services[_].credentials.pluginstringNoThe name of the plugin to use for authentication
Example

Using a custom plugin for service credentials:

services:
  my_service:
    url: https://example.com/v1
    credentials:
      plugin: my_custom_auth
plugins:
  my_custom_auth:
    foo: bar
package plugins

import (
	"github.com/open-policy-agent/opa/plugins"
	"github.com/open-policy-agent/opa/plugins/rest"
	"github.com/open-policy-agent/opa/runtime"
	"github.com/open-policy-agent/opa/util"
)

type Config struct {
	Foo string `json:"foo"`
}

type PluginFactory struct{}

type Plugin struct {
	manager  *plugins.Manager
	config   Config
	stop     chan chan struct{}
	reconfig chan interface{}
}

func (p *PluginFactory) Validate(manager *plugins.Manager, config []byte) (interface{}, error) {
	var parsedConfig Config
	if err := util.Unmarshal(config, &parsedConfig); err != nil {
		return nil, err
	}
	return &parsedConfig, nil
}

func (p *PluginFactory) New(manager *plugins.Manager, config interface{}) plugins.Plugin {
	return &Plugin{
		config:   *config.(*Config),
		manager:  manager,
		stop:     make(chan chan struct{}),
		reconfig: make(chan interface{}),
	}
}

func (p *Plugin) Start(ctx context.Context) error {
	p.manager.UpdatePluginStatus(Name, &plugins.Status{State: plugins.StateOK})
	return nil
}

func (p *Plugin) Stop(ctx context.Context) {
	done := make(chan struct{})
	p.stop <- done
	_ = <-done
	p.manager.UpdatePluginStatus(Name, &plugins.Status{State: plugins.StateNotReady})
	return
}

func (p *Plugin) Reconfigure(ctx context.Context, config interface{}) {
	p.reconfig <- config
	return
}

func (p *Plugin) NewClient(c rest.Config) (*http.Client, error) {
	t, err := rest.DefaultTLSConfig(c)
	if err != nil {
		return nil, err
	}
	return rest.DefaultRoundTripperClient(t, *c.ResponseHeaderTimeoutSeconds), nil
}

func (p *Plugin) Prepare(req *http.Request) error {
	req.Header.Add("X-Custom-Auth-Protocol", "knock knock")
	return nil
}

func init() {
	runtime.RegisterPlugin("my_custom_auth", &PluginFactory{})
}

Miscellaneous

FieldTypeRequiredDescription
labelsobjectYesSet of key-value pairs that uniquely identify the OPA instance. Labels are included when OPA uploads decision logs and status information.
default_decisionstringNo (default: /system/main)Set path of default policy decision used to serve queries against OPA’s base URL.
default_authorization_decisionstringNo (default: /system/authz/allow)Set path of default authorization decision for OPA’s API.
pluginsobjectNo (default: {})Location for custom plugin configuration. See Plugins for details.

Keys

Keys is a dictionary mapping the key name to the actual key and optionally the algorithm and scope.

FieldTypeRequiredDescription
keys[_].keystringYes (unless private_key provided)PEM encoded public key to use for signature verification.
keys[_].private_keystringYes (unless key provided`)PEM encoded private key to use for signing.
keys[_].algorithmstringNo (default: RS256)Name of the signing algorithm.
keys[_].scopestringNoScope to use for bundle signature verification.

Note: If the scope is provided in a bundle’s signing configuration (ie. bundles[_].signing.scope), it takes precedence over keys[_].scope.

The following signing algorithms are supported:

NameDescription
ES256ECDSA using P-256 and SHA-256
ES384ECDSA using P-384 and SHA-384
ES512ECDSA using P-521 and SHA-512
HS256HMAC using SHA-256
HS384HMAC using SHA-384
HS512HMAC using SHA-512
PS256RSASSA-PSS using SHA256 and MGF1-SHA256
PS384RSASSA-PSS using SHA384 and MGF1-SHA384
PS512RSASSA-PSS using SHA512 and MGF1-SHA512
RS256RSASSA-PKCS-v1.5 using SHA-256
RS384RSASSA-PKCS-v1.5 using SHA-384
RS512RSASSA-PKCS-v1.5 using SHA-512

Caching

Caching represents the configuration of the inter-query cache that built-in functions can utilize.

FieldTypeRequiredDescription
caching.inter_query_builtin_cache.max_size_bytesint64NoInter-query cache size limit in bytes. OPA will drop old items from the cache if this limit is exceeded. By default, no limit is set.

Bundles

Bundles are defined with a key that is the name of the bundle. This name is used in the status API, decision logs, server provenance, etc.

Each bundle can be configured to verify a bundle signature using the keyid and scope fields. The keyid is the name of one of the keys listed under the keys entry.

Signature verification fails if the bundles[_].signing field is configured on a bundle but no .signatures.json file is included in the actual bundle gzipped tarball.

FieldTypeRequiredDescription
bundles[_].resourcestringNo (default: bundles/<name>)Resource path to use to download bundle from configured service.
bundles[_].servicestringYesName of service to use to contact remote server.
bundles[_].polling.min_delay_secondsint64No (default: 60)Minimum amount of time to wait between bundle downloads.
bundles[_].polling.max_delay_secondsint64No (default: 120)Maximum amount of time to wait between bundle downloads.
bundles[_].persistboolNoPersist activated bundles to disk.
bundles[_].signing.keyidstringNoName of the key to use for bundle signature verification.
bundles[_].signing.scopestringNoScope to use for bundle signature verification.
bundles[_].signing.exclude_filesarrayNoFiles in the bundle to exclude during verification.
bundles[_].size_limit_bytesint64No (default: 1073741824)Size limit for individual files contained in the bundle.

Status

FieldTypeRequiredDescription
status.servicestringYesName of service to use to contact remote server.
status.partition_namestringNoPath segment to include in status updates.
status.consolebooleanNo (default: false)Log the status updates locally at info level to the console. When enabled alongside a remote status update API the service must be configured, the default service selection will be disabled.

Decision Logs

FieldTypeRequiredDescription
decision_logs.servicestringNoName of the service to use to contact remote server. If no plugin is specified, and console logging is disabled, this will default to the first service name defined in the Services configuration.
decision_logs.partition_namestringNoPath segment to include in status updates.
decision_logs.reporting.buffer_size_limit_bytesint64NoDecision log buffer size limit in bytes. OPA will drop old events from the log if this limit is exceeded. By default, no limit is set.
decision_logs.reporting.upload_size_limit_bytesint64No (default: 32768)Decision log upload size limit in bytes. OPA will chunk uploads to cap message body to this limit.
decision_logs.reporting.min_delay_secondsint64No (default: 300)Minimum amount of time to wait between uploads.
decision_logs.reporting.max_delay_secondsint64No (default: 600)Maximum amount of time to wait between uploads.
decision_logs.mask_decisionstringNo (default: system/log/mask)Set path of masking decision.
decision_logs.pluginstringNoUse the named plugin for decision logging. If this field exists, the other configuration fields are not required.
decision_logs.consolebooleanNo (default: false)Log the decisions locally at info level to the console. When enabled alongside a remote decision logging API the service must be configured, the default service selection will be disabled.

Discovery

FieldTypeRequiredDescription
discovery.namestringYesName of the discovery configuration to download.
discovery.resourcestringNo (default: /bundles/<name>)Resource path to use to download bundle from configured service.
discovery.prefixstringNo (default: bundles)Deprecated: Use resource instead. Path prefix to use to download configuration from remote server.
discovery.decisionstringNo (default: value of discovery.name configuration field)Name of the OPA query that will be used to calculate the configuration
discovery.polling.min_delay_secondsint64No (default: 60)Minimum amount of time to wait between configuration downloads.
discovery.polling.max_delay_secondsint64No (default: 120)Maximum amount of time to wait between configuration downloads.
discovery.signing.keyidstringNoName of the key to use for bundle signature verification.
discovery.signing.scopestringNoScope to use for bundle signature verification.
discovery.signing.exclude_filesarrayNoFiles in the bundle to exclude during verification.