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Request permissions

To access certain powerful JavaScript globals or API methods, a snap must ask the user for permission. Snaps follow the EIP-2255 wallet permissions specification, and you must specify a snap's required permissions in the initialPermissions field of the manifest file.

RPC API permissions​

You must request permission to use any restricted JSON-RPC API methods.

For example, to request to use snap_confirm, add the following to the manifest file:

...
"initialPermissions": {
  "snap_confirm": {}
},
...

Endowments​

You can specify the following endowments in the manifest file.

endowment:long-running​

A snap that is computationally heavy and can't finish execution within the snap lifecycle requirements can request the endowment:long-running permission. This permission allows the snap to run indefinitely while processing RPC requests.

...
"initialPermissions": {
  "endowment:long-running": {}
},
...

endowment:network-access​

A snap that must access the internet must request the endowment:network-access permission. This permission exposes the global networking APIs fetch and WebSocket to the Snaps execution environment.

caution

XMLHttpRequest is never available in Snaps, and you should replace it with fetch. If your dependencies are using XMLHttpRequest, you can patch it away.

...
"initialPermissions": {
  "endowment:network-access": {}
},
...

endowment:transaction-insight​

For snaps that provide transaction insights, the snap can request the endowment:transaction-insight permission. This permission grants a snap read-only access to raw transaction payloads, before they're accepted for signing by the user, by exporting the onTransaction method.

...
"initialPermissions": {
  "endowment:transaction-insight": {}
},
...

endowment:cronjob​

For snaps that wants to run periodic actions for the user, the snap can request the endowment:cronjob permission. This permission allows a snap to specify periodic requests that trigger the exported onCronjob method.

Cronjobs are specified as follows:

{
  "initialPermissions": {
    "endowment:cronjob": {
      "jobs": [
        {
          "expression": {
            "minute": "*",
            "hour": "*",
            "dayOfMonth": "*",
            "month": "*",
            "dayOfWeek": "*"
          },
          "request": {
            "method": "exampleMethodOne",
            "params": {
              "param1": "foo"
            }
          }
        },
        {
          "expression": "* * * * *",
          "request": {
            "method": "exampleMethodTwo",
            "params": {
              "param1": "bar"
            }
          }
        }
      ]
    }
  }
}