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Before configuring your field to get its options from the API, you need to create a data source by providing the endpoint url, the response type (JSON / XML) and the authorization type. Depending on the authorization type, you may need to provide some credentials. Additionally, you need to provide a name for your data source.
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The app sends request to your external APIs over Atlassian servers. If your external APIs are protected, you need to follow the instructions in https://support.atlassian.com/organization-administration/docs/ip-addresses-and-domains-for-atlassian-cloud-products/ to provide access to the requests coming from the IP ranges of Atlassian servers.
Configuring the field
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From the "Configurations" tab, you can configure options of select, multi select and checkbox typed custom fields to be fed from your external APIs. For each context of the custom field, you can have at most one configuration. Click to the “Configure” button next to the field that you would like to configure.
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