Safelisting with persisted queries

With GraphOS Enterprise, you can enhance your supergraph's security by maintaining a persisted query list (PQL) for your supergraph's self-hosted router. To create and update the PQL, first-party apps register trusted operations to the PQL at build time.

At runtime, the Apollo Router checks incoming requests against the PQL, which can act as operation safelist, depending on your router configuration.

Your router can use its persisted query list (PQL) to both protect your supergraph and speed up your clients' operations:

• When you enable safelisting, your router rejects any incoming operations not registered in its PQL.

• Client apps can execute an operation by providing its PQL-specified ID instead of the entire operation string.

  • Requesting by ID can significantly reduce latency and bandwidth usage for large operation strings.
  • Your router can require that clients provide operations by ID and reject full operation strings—even operation strings present in the PQL.

Differences from automatic persisted queries

The Apollo Router also supports a related feature called automatic persisted queries (APQ). With APQ, clients can execute a GraphQL operation by sending the SHA256 hash of its operation string instead of the entire string. APQ doesn't support safelisting because the router updates its APQ cache over time with any operations it receives.

For more details on differences between APQ and this feature, see the GraphOS persisted queries documentation.

Implementation

Enabling operation safelisting has a few steps:

1. PQL creation and linking
2. Router configuration
3. Operation registration
4. Client updates

This article details the router configuration step. For more information on other configuration aspects, see the GraphOS persisted queries documentation.

Router configuration

As soon as a graph variant has a linked PQL, you can configure router instances to fetch and use the PQL by following these steps:

1. Ensure your router instances are ready to work with PQLs:

   • Make sure you're using version 1.32.0 or later of the Apollo Router. (The feature was released in preview in version 1.25.0 and made generally available in 1.32.0.)
   • Make sure your router instances are connected to your GraphOS Enterprise organization and that they're associated with a variant that your PQL is linked to.

2. Set your desired security level in your router's YAML config file. For supported options, see router security levels. When first implementing persisted queries, it's best to start with audit—or "dry run"—mode.

3. Deploy your updated router instances to begin using your PQL.

Once your organization's PQL has registered all your clients' operations and you've ensured your client apps are only sending registered operations, you can update your router configuration to the safelisting security level.

Router security levels

The Apollo Router supports the following security levels, in increasing order of restrictiveness:

• Allow operation IDs: Clients can optionally execute an operation by providing the operation's PQL-specified ID.
  • All other levels also provide this core capability.
  • This level doesn't provide safelisting.
• Audit mode: Executing operations by providing a PQL-specified ID is still optional, but the router also logs any unregistered operations.
  • The level serves as a dry run and helps you identify operations you may still need to register before turning on safelisting.
• Safelisting: The router rejects any incoming operations not present in its PQL. Requests can use either ID or operation string.
  • Before moving to this security level, ensure all your client operations are present in your PQL.
• Safelisting with IDs only: The router rejects any freeform GraphQL operations. Clients can only execute operations by providing their PQL-specified IDs.
  • Before moving to this security level, ensure all your clients execute operations by providing their PQL-specified ID.

When adopting persisted queries, you should start with a less restrictive security such as audit mode. You can then enable increasingly restrictive levels after your teams have updated all clients.

See below for sample YAML configurations for each level. Refer to the router configuration options for option details.

Allow operation IDs

To use persisted queries only to reduce network bandwidth and latency (not for safelisting), add the following minimal configuration:

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persisted_queries:
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  enabled: true

This mode lets clients execute operations by providing their PQL-specified ID instead of the full operation string. Your router also continues to accept full operation strings, even for operations that don't appear in its PQL.

Audit mode (dry run)

Turning on logging is crucial for gauging your client apps' readiness for safelisting. The logs identify which operations you need to either add to your PQL or stop your client apps from making.

To enable logging for unregistered queries, enable the log_unknown property:

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persisted_queries:
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  enabled: true
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  log_unknown: true

Unregistered operations appear in your router's logs.

For example:

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2023-08-02T11:51:59.833534Z  WARN [trace_id=5006cef73e985810eb086e5900945807] unknown operation operation_body="query ExampleQuery {\n  me {\n    id\n  }\n}\n"

If your router receives an operation registered in the PQL, no log message will be output.

You can use these router logs to audit operations sent to your router and ask client teams to add new ones to your PQL if necessary.

Safelisting

With the following configuration, your router allows only GraphQL operations that are present in its PQL while rejecting all other operations:

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persisted_queries:
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  enabled: true
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  log_unknown: true
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  safelist:
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    enabled: true
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    require_id: false
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apq:
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  enabled: false # APQ must be turned off

To execute an operation, clients can provide its PQL-specified ID or full operation string. The router rejects unregistered operations, and if log_unknown is true, those operations appear in your router's logs.

Safelisting with IDs only

With the following configuration, your router rejects all operation strings and only accepts registered operation IDs:

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persisted_queries:
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  enabled: true
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  log_unknown: true
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  safelist:
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    enabled: true
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    require_id: true 
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apq:
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  enabled: false # APQ must be turned off

If you want to use this security level, you should always first set up safelisting with operation strings allowed. ID-only safelisting requires all your clients to execute operations via PQL-specified ID instead of an operation string. While making those necessary changes, you can use the less restrictive safelisting mode in your router.

With log_unknown set to true, the router logs all rejected operations, including those registered to your PQL but that used the full operation string rather than the PQL-specified ID.

Configuration options

The router provides four configuration options that you can combine to create the recommended security levels. This section details each configuration option. Refer to the security levels section for recommended combinations.

persisted_queries

This base configuration enables the feature. All other configuration options build off this one.

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persisted_queries:
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  enabled: true

log_unknown

Adding log_unknown: true to persisted_queries configures the router to log any incoming operations not registered to the PQL.

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persisted_queries:
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  enabled: true
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  log_unknown: true

If used with the safelist option, the router logs unregistered and rejected operations. With safelist.required_id off, the only rejected operations are unregistered ones. If safelist.required_id is turned on, operations can be rejected even when registered because they use operation IDs rather than operation strings.

safelist

Adding safelist: true to persisted_queries causes the router to reject any operations that haven't been registered to your PQL.

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persisted_queries:
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  enabled: true
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  safelist:
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    enabled: true
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apq:
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  enabled: false

By default, the require_id suboption is false, meaning the router accepts both operation IDs and operation strings as long as the operation is registered.

require_id

Adding require_id: true to the safelist option causes the router to reject any operations that either:

• haven't been registered to your PQL
• use a full operation string rather than the operation ID

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persisted_queries:
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  enabled: true
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  safelist:
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    enabled: true
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    require_id: true
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apq:
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  enabled: false

Limitations

• Unsupported with offline license. An Apollo Router using an offline Enterprise license cannot use safelisting with persisted queries. The feature relies on Apollo Uplink to fetch persisted query manifests, so it doesn't work as designed when the router is disconnected from Uplink.