Automatically unmarshal complex configuration types

[blampe]

Non-primitive config fields are automatically JSON.Stringify-d when sent to the server:

https://github.com/pulumi/pulumi/blob/f500bef2fa732aab23c644dc07ed9b101a9cfaaf/pkg/codegen/nodejs/gen.go#L794-L797

				// provider properties must be marshaled as JSON strings.
				if r.IsProvider && !isStringType(prop.Type) {
					arg = fmt.Sprintf("pulumi.output(%s).apply(JSON.stringify)", arg)
				}

However we aren't unmarshaling them on the receiving end. A type like this results in an error:

package foo

type Config struct {
   Foo []string `pulumi:"foo"`
}

error: ... provider returned an unexpected error from Configure: unknown mapper error: Field 'foo' on 'foo.Config' must be a '[]string'; got 'string' instead

The bridge seems to handle this here:

https://github.com/pulumi/pulumi-terraform-bridge/blob/0f7ccfdef31d3fddd4eb46c9770d460bbfbe81e3/pkg/tfbridge/config_encoding.go#L150C11-L174

    var jsonString string
    var jsonStringDetected, jsonStringSecret bool


    if pv.IsString() {
        jsonString = pv.StringValue()
        jsonStringDetected = true
    }


    if opts.KeepSecrets && pv.IsSecret() && pv.SecretValue().Element.IsString() {
        jsonString = pv.SecretValue().Element.StringValue()
        jsonStringDetected = true
        jsonStringSecret = true
    }


    if jsonStringDetected {
        v, err := enc.convertStringToPropertyValue(jsonString, shimType)
        if err != nil {
            return nil, fmt.Errorf("error unmarshalling property %q: %w", key, err)
        }
        if jsonStringSecret {
            s := resource.MakeSecret(v)
            return &s, nil
        }
        return &v, nil
    }

I think this is essentially the issue:

pulumi-go-provider/provider.go

Lines 710 to 711 in 2b02372

	func (p *provider) Configure(ctx context.Context, req *rpc.ConfigureRequest) (*rpc.ConfigureResponse, error) {
	argMap, err := p.getMap(req.GetArgs())

We unmarshal the provider's config the same way we unmarshal properties, but this JSON behavior is unique to config.