Easily create serverless workflows directly in Go with the power of Fn Flow.

Simply import this library into your go function, build and deploy onto Fn. Flows use the fdk-go to handle interacting with Fn, below is an example flow:

package main import ( "fmt" "strings" "time"	fdk "github.com/fnproject/fdk-go"	flows "github.com/fnproject/flow-lib-go" ) func init() { flows.RegisterAction(strings.ToUpper) flows.RegisterAction(strings.ToLower) } func main() {	fdk.Handle(flows.WithFlow( fdk.HandlerFunc(func(ctx context.Context, r io.Reader, w io.Writer) { cf := flows.CurrentFlow().CompletedValue("foo") valueCh, errorCh := cf.ThenApply(strings.ToUpper).ThenApply(strings.ToLower).Get() select { case value := <-valueCh: fmt.Fprintf(w, "Flow succeeded with value %v", value) case err := <-errorCh: fmt.Fprintf(w, "Flow failed with error %v", err) case <-time.After(time.Minute * 1): fmt.Fprintf(w, "Timed out!")	}	}),	) }

A variety of example use-cases is provided here.

Go's gob serialization mechanism is used to encode/decode values for communication with the completer.

Booleans, string, structs, arrays and slices are supported. Functions, closures and channels are not.

Since Go does not support serializing closures/functions due to its statically compiled nature, they are in fact not serialized at all. Go functions implementing a continuation need to be explicitly registered by calling flows.RegisterAction(actionFunction) typically inside the handler's init function. Registering actions assigns a unique and stable key that can be serialized and used to look up a pointer to the function during a continuation invocation.

See above.

No. Only continuation actions implemented with functions are supported, since they are stateless. No state will be serialized with a continuation. Although possible, invoking a method receiver is not currently supported inside continuations.

Go allows functions to return error types in addition to a result via its support for multiple return values. If a continuation function returns a (non-nil) error as its second return value, its error message will be serialized and form the failed value of that stage.

If a panic occurs while invoking the continuation function, the panic value will be captured and the stage failed with the same value.

Yes. flows.CurrentFlow().InvokeFunction("your_function_id", req), where the function ID is a value like 01CQV4NEGMNG8G00GZJ0000002 and can be resolved with the following command:

fn inspect function your_app your_function | grep fnproject.io/fn/invokeEndpoint 

See here for a full example.