--- title: Multipart upload metadata description: Define Workers configuration in JSON metadata for multipart form-data script uploads. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) # Multipart upload metadata Note There is a new API for uploading Workers. Refer to [these docs](https://developers.cloudflare.com/workers/platform/infrastructure-as-code#cloudflare-rest-api) for more information. If you're using the [Workers Script Upload API](https://developers.cloudflare.com/api/resources/workers/subresources/scripts/methods/update/) or [Version Upload API](https://developers.cloudflare.com/api/resources/workers/subresources/scripts/subresources/versions/methods/create/) directly, `multipart/form-data` uploads require you to specify a `metadata` part. This metadata defines the Worker's configuration in JSON format, analogue to the [wrangler.toml file](https://developers.cloudflare.com/workers/wrangler/configuration/). ## Sample `metadata` ``` { "main_module": "main.js", "bindings": [ { "type": "plain_text", "name": "MESSAGE", "text": "Hello, world!" } ], "compatibility_date": "2021-09-14" } ``` Note See examples of metadata being used with the Workers Script Upload API [here](https://developers.cloudflare.com/workers/platform/infrastructure-as-code#cloudflare-rest-api). ## Attributes The following attributes are configurable at the top-level. Note At a minimum, the `main_module` key is required to upload a Worker. * `main_module` ` string ` required * The part name that contains the module entry point of the Worker that will be executed. For example, `main.js`. * `assets` ` object ` optional * [Asset](https://developers.cloudflare.com/workers/static-assets/) configuration for a Worker. * `config` ` object ` optional * [html\_handling](https://developers.cloudflare.com/workers/static-assets/routing/advanced/html-handling/) determines the redirects and rewrites of requests for HTML content. * [not\_found\_handling](https://developers.cloudflare.com/workers/static-assets/#routing-behavior) determines the response when a request does not match a static asset. * `jwt` field provides a token authorizing assets to be attached to a Worker. * `keep_assets` ` boolean ` optional * Specifies whether assets should be retained from a previously uploaded Worker version; used in lieu of providing a completion token. * `bindings` array\[object\] optional * [Bindings](#bindings) to expose in the Worker. * `placement` ` object ` optional * [Smart placement](https://developers.cloudflare.com/workers/configuration/placement/) object for the Worker. * `mode` field only supports `smart` for automatic placement. * `compatibility_date` ` string ` optional * [Compatibility Date](https://developers.cloudflare.com/workers/configuration/compatibility-dates/#setting-compatibility-date) indicating targeted support in the Workers runtime. Backwards incompatible fixes to the runtime following this date will not affect this Worker. Highly recommended to set a `compatibility_date`, otherwise if on upload via the API, it defaults to the oldest compatibility date before any flags took effect (2021-11-02). * `compatibility_flags` array\[string\] optional * [Compatibility Flags](https://developers.cloudflare.com/workers/configuration/compatibility-flags/#setting-compatibility-flags) that enable or disable certain features in the Workers runtime. Used to enable upcoming features or opt in or out of specific changes not included in a `compatibility_date`. ## Additional attributes: [Workers Script Upload API](https://developers.cloudflare.com/api/resources/workers/subresources/scripts/methods/update/) For [immediately deployed uploads](https://developers.cloudflare.com/workers/configuration/versions-and-deployments/#upload-a-new-version-and-deploy-it-immediately), the following **additional** attributes are configurable at the top-level. Note Except for `annotations`, these attributes are **not available** for version uploads. * `migrations` array\[object\] optional * [Durable Objects migrations](https://developers.cloudflare.com/durable-objects/reference/durable-objects-migrations/) to apply. * `logpush` ` boolean ` optional * Whether [Logpush](https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/hostname-analytics/#logpush) is turned on for the Worker. * `tail_consumers` array\[object\] optional * [Tail Workers](https://developers.cloudflare.com/workers/observability/logs/tail-workers/) that will consume logs from the attached Worker. * `tags` array\[string\] optional * List of strings to use as tags for this Worker. * `annotations` ` object ` optional * Annotations object for the Worker version created by this upload. Also available on the [Version Upload API](#additional-attributes-version-upload-api). * `workers/message` specifies a custom message for the version. * `workers/tag` specifies a custom identifier for the version. ## Additional attributes: [Version Upload API](https://developers.cloudflare.com/api/resources/workers/subresources/scripts/subresources/versions/methods/create/) For [version uploads](https://developers.cloudflare.com/workers/configuration/versions-and-deployments/#upload-a-new-version-to-be-gradually-deployed-or-deployed-at-a-later-time), the following **additional** attributes are configurable at the top-level. * `annotations` ` object ` optional * Annotations object specific to the Worker version. * `workers/message` specifies a custom message for the version. * `workers/tag` specifies a custom identifier for the version. * `workers/alias` specifies a custom alias for this version. ## Bindings Workers can interact with resources on the Cloudflare Developer Platform using [bindings](https://developers.cloudflare.com/workers/runtime-apis/bindings/). Refer to the JSON example below that shows how to add bindings in the `metadata` part. ``` { "bindings": [ { "type": "ai", "name": "" }, { "type": "analytics_engine", "name": "", "dataset": "" }, { "type": "assets", "name": "" }, { "type": "browser_rendering", "name": "" }, { "type": "d1", "name": "", "id": "" }, { "type": "durable_object_namespace", "name": "", "class_name": "" }, { "type": "hyperdrive", "name": "", "id": "" }, { "type": "kv_namespace", "name": "", "namespace_id": "" }, { "type": "mtls_certificate", "name": "", "certificate_id": "" }, { "type": "plain_text", "name": "", "text": "" }, { "type": "queue", "name": "", "queue_name": "" }, { "type": "r2_bucket", "name": "", "bucket_name": "" }, { "type": "secret_text", "name": "", "text": "" }, { "type": "service", "name": "", "service": "", "environment": "production" }, { "type": "vectorize", "name": "", "index_name": "" }, { "type": "version_metadata", "name": "" } ] } ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/configuration/","name":"Configuration"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/configuration/multipart-upload-metadata/","name":"Multipart upload metadata"}}]} ```