Fetch Resolvers

Fetch resolvers are functions to fetch resources from the source (a cloud provider for example).

TableResolver

This is the main type of fetch resolver:

type TableResolver func(ctx context.Context, meta ClientMeta, parent *Resource, res chan interface{}) error

TableResolver allows you to access the cloud resource using the given passed *Client and fetch all resources of that type. Finally, you send the fetch items into the passed res channel argument. The TableResolver is flexible allowing you to define your own pagination logic or any other logic for that matter, and pass the results to the channel.

tip

The collector in the SDK is slice-aware, so if you have a slice of resources, you can just push the slice as a whole, without iterating.

Here's an example from the provider template:

func fetchDemoResources(ctx context.Context, meta schema.ClientMeta, parent *schema.Resource, res chan interface{}) error {
    c := meta.(*client.Client)
    _ = c
    // Fetch using the third party client and put the result in res
    // res <- c.ThirdPartyClient.getData()
    return nil
}

PostResourceResolver (RowResolver)

This optional resolver is called after all columns have been resolved, and before resource is inserted to database. PostResourceResolver is the name in the schema.Table struct.

type RowResolver func(ctx context.Context, meta ClientMeta, resource *Resource) error

Here's an example from the AWS Provider's SNS Topics resource, getting SNS topic attributes in one go and setting various fields:

func resolveTopicAttributes(ctx context.Context, meta schema.ClientMeta, resource *schema.Resource) error {
    topic, ok := resource.Item.(types.Topic)
    
    // ...

    output, err := svc.GetTopicAttributes(ctx, &params, func(o *sns.Options) {
        o.Region = c.Region
    })

    // ...

    // Set all attributes
    if err := resource.Set("subscriptions_confirmed", cast.ToInt(output.Attributes["SubscriptionsConfirmed"])); err != nil {
        return err
    }
    if err := resource.Set("subscriptions_deleted", cast.ToInt(output.Attributes["SubscriptionsDeleted"])); err != nil {
        return err
    }
    // ... More attributes are set here ...

    return nil
}