Inter-function Communication Feature Asking

[DanielLee343]

Hi, Alex. Thanks for the clear guide on faasd!

I'm wondering if there's a feature for payload/data be transferred between functions, similar to OpenWhisk’s Action Sequence, Fn flow, or AWS Step Functions?

Say I have a stack.yml as follows

provider:
  name: openfaas
  gateway: http://127.0.0.1:8080

functions:
  fn1:
    lang: go
    handler: ./fn1
    image: fn1:latest
  fn2:
    lang: go
    handler: ./fn2
    image: fn2:latest

And each function is invoked by curl. I would like to feed fn2 with fn1's response body, or even send http request during function runtime (although not a best practice). I haven't found such feature in OpenFaaS documents. If any, is it relative to the architecture (Kubernetes/faasd)? Could you suggest any general best practices for multi-function communication in OpenFaaS? I appreciate that!

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• Versions:

go version

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faasd version

[alexellis]

Hi @DanielLee343 thanks for your interest.

Unfortunately, you've deleted the issue template which has some important questions.

For sending data between functions, we recommend calling via the gateway and/or using async.

This is covered in detail in the docs and the eBook - https://gumroad.com/l/serverless-for-everyone-else

You don't say whether you have a copy, but you should find everything you need there.

Alex

[DanielLee343]

Hi @alexellis
I read the eBook and tried to setup an async call within a function. There is some "vendor" problem whenever I want to re-build the image.

To reproduce

faas-cli template store pull golang-http
faas-cli new --lang golang-http fn1 --prefix lyuze
mv f1.yml stack.yml
faas-cli new --lang golang-http fn2 --prefix lyuze --append stack.yml 
faas-cli up -f stack.yml

Everything is fine here, then I change the function code to

package function

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"

	handler "github.com/openfaas/templates-sdk/go-http"
)

func Handle(req handler.Request) (handler.Response, error) {
    reqBody := url.Values{
        "name":       {"John Doe"},
        "occupation": {"gardener"},
    }
    resp, err := http.PostForm("http://gateway.openfaas.svc.cluster.local:8080/function/fn2", reqBody)
    if err != nil {
        log.Fatal(err)
        return handler.Response{}, err
    }
    defer resp.Body.Close()
    bodyByte, err := ioutil.ReadAll(resp.Body)
    fmt.Print("Body: %s", bodyByte)

    // message := fmt.Sprintf("Body: %s", string(req.Body))

    return handler.Response{
        Body:       bodyByte,
        StatusCode: http.StatusOK,
    }, err
}

I tried to re-build the image but it shows (no matter what changes I made to the code):

$ faas-cli up -f fn1.yml 
...
Step 18/37 : RUN test -z "$(gofmt -l $(find . -type f -name '*.go' -not -path "./vendor/*" -not -path "./function/vendor/*"))" || { echo "Run \"gofmt -s -w\" on your Golang code"; exit 1; }
 ---> Running in e14ea422864c
Run "gofmt -s -w" on your Golang code
The command '/bin/sh -c test -z "$(gofmt -l $(find . -type f -name '*.go' -not -path "./vendor/*" -not -path "./function/vendor/*"))" || { echo "Run \"gofmt -s -w\" on your Golang code"; exit 1; }' returned a non-zero code: 1
[0] < Building fn1 done in 8.82s.
[0] Worker done.

Total build time: 8.82s
Errors received during build:
- [fn1] received non-zero exit code from build, error: The command '/bin/sh -c test -z "$(gofmt -l $(find . -type f -name '*.go' -not -path "./vendor/*" -not -path "./function/vendor/*"))" || { echo "Run \"gofmt -s -w\" on your Golang code"; exit 1; }' returned a non-zero code: 1

Attempts I Tried

I tried to build with faas-cli build --build-arg GO111MODULE=on, or go mod tidy before build, neither worked.
I also saw this merge but didn't get anything from it.
I also changed to use template golang-middleware, didn't work either.

[alexellis]

Hi, this example is not part of Serverless For Everyone Else, this is a Go example.

Where did you get it from?

[DanielLee343]

This is not from the eBook, but another issue with golang-middleware/golang-http template.
I simply changed the original template code of golang-middleware to the following, which is from your youtube video (or the go-http-template example):

package function

import (
	"net/http"
)

//handles a request
func Handle(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodGet {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("Access granted!"))
		return
	}
	w.WriteHeader(http.StatusMethodNotAllowed)
	w.Write([]byte("Access not allowed!"))

}

And faas-cli build -f fn1.yml throws the above error.
A temp fix is commenting out the following line in the template Dockerfile:

RUN test -z "$(gofmt -l $(find . -type f -name '*.go' -not -path "./vendor/*" -not -path "./function/vendor/*"))" || { echo "Run \"gofmt -s -w\" on your Golang code"; exit 1; }

[alexellis]

The example repo should be working out of the box. If not can you create a separate issue in the template's repo?

We will get this closed since the two are not connected.

Thanks