Function as a service with OpenFaaS on Banzai Cloud Pipeline · Banzai Cloud

At Banzai Cloud we provision different frameworks and tools like Spark, Zeppelin, Kafka, Tensorflow, etc to our Pipeline PaaS (built on Kubernetes). Last week we have added serverless capabilities to Pipeline, using OpenFaas.

This blog post explains how to deploy OpenFaaS to Kubernetes using Pipeline and invoke an example function running on it. We shall separate the provisioning of the serverless frameworks we support (this post is about OpenFaaS but Pipeline equally supports Kubeless as well) and the invocation of functions through the Pipeline API or CI/CD workflow dispatched to any of the supported serverless frameworks we deploy to Kubernetes.

Create a Kubernetes cluster

First thing we need is a Kubernetes cluster. Kubernetes clusters can be easily provisioned with Pipeline with a simple REST API call on any of the major cloud providers or managed Kubernetes offerings (AWS, Azure, Google). In order to deploy Pipeline please follow these instructions. Once Pipeline is up and running, Kubernetes clusters can be created using REST API calls – see the Postman collection we have created for the REST API exposed by the Pipeline.

Deploy OpenFaaS to a Kubernetes cluster

OpenFaas can be deployed into a Kubernetes cluster with a RESTful API call to Pipeline. Look for the Deployment Create API call in the Postman collection. To invoke Deployment Create API we need to provide two parameters:

Once the cluster is created and deployed to Pipeline it will look like this.

Deploy a Function to OpenFaaS

OpenFaas provides a UI for deploying functions. Execute the Cluster Public Endpoints REST API call against the Pipeline to get the URL through which OpenFaaS Portal is exposed. Look for the endpoint named pipeline-traefik. The host field of this endpoint is the URL through which the OpenFaaS Portal is exposed under the ui/ path (http://{{public_endppoint_host}}/ui/).

For deploying a function we need to specify the Docker image (pullable from DockerHub) that contains the binary of our function.

I took the N-queens problem written in GoLang and adapted for OpenFaaS.

main.go
package main import ( "bytes" "fmt" "math/rand" "strings" "github.com/MaxHalford/gago" "io/ioutil" "os" "strconv" ) // N_QUEENS is the size of each genome. var nqueens = 15 // Positions is a slice of ints. type Positions []int // String prints a chess board and marks with an x the queen positions. func (P Positions) String() string { var board bytes.Buffer for _, p := range P { board.WriteString(strings.Repeat(" .", p)) board.WriteString(" \u2655") board.WriteString(strings.Repeat(" .", nqueens-p-1)) board.WriteString("\n") } return board.String() } func absInt(n int) int { if n < 0 { return -n } return n } // Evaluate a slice of Positions by counting the number of diagonal collisions. // Queens are on the same diagonal if there row distance is equal to their // column distance. func (P Positions) Evaluate() float64 { var collisions float64 for i := 0; i < len(P); i++ { for j := i + 1; j < len(P); j++ { if j-i == absInt(P[i]-P[j]) { collisions++ } } } return collisions } // Mutate a slice of Positions by permuting it's values. func (P Positions) Mutate(rng *rand.Rand) { gago.MutPermuteInt(P, 3, rng) } // Crossover a slice of Positions with another by applying partially mapped // crossover. func (P Positions) Crossover(Y gago.Genome, rng *rand.Rand) { gago.CrossPMXInt(P, Y.(Positions), rng) } // Clone a slice of Positions. func (P Positions) Clone() gago.Genome { var PP = make(Positions, len(P)) copy(PP, P) return PP } // MakeBoard creates a random slices of positions by generating random number // permutations in [0, N_QUEENS). func MakeBoard(rng *rand.Rand) gago.Genome { var positions = make(Positions, nqueens) for i, position := range rng.Perm(nqueens) { positions[i] = position } return gago.Genome(positions) } func main() { // read function input input, err := ioutil.ReadAll(os.Stdin) if err != nil { fmt.Println(err) return } nqueens, err = strconv.Atoi(strings.TrimSpace(string(input))) if err != nil { fmt.Println(err) return } var ga = gago.Generational(MakeBoard) ga.Initialize() for ga.HallOfFame[0].Fitness > 0 { ga.Evolve() } // print function output fmt.Println(ga.HallOfFame[0].Genome) fmt.Printf("Optimal solution obtained after %d generations in %s\n", ga.Generations, ga.Age) } 

The Dockerfile to build the above function into a Docker image for OpenFaaS:

Dockerfile
FROM golang:1.9.2-alpine as builder RUN apk --no-cache add make curl git glide \ && curl -sL https://github.com/openfaas/faas/releases/download/0.7.0/fwatchdog > /usr/bin/fwatchdog \ && chmod +x /usr/bin/fwatchdog WORKDIR /go/src/n_queens # add n_queens sources COPY main.go . # download n_queens dependencies RUN glide init -non-interactive RUN sed -i '/- package: github.com\/MaxHalford\/gago/a \ \ version: ~0.4.1' glide.yaml RUN glide update # build n_queens binary RUN go install FROM alpine:3.6 # Needed to reach the hub RUN apk --no-cache add ca-certificates COPY --from=builder /usr/bin/fwatchdog /usr/bin/fwatchdog COPY --from=builder /go/bin/n_queens /usr/bin/n_queens ENV fprocess "/usr/bin/n_queens" CMD ["/usr/bin/fwatchdog"] 

This Docker file is a multistage Docker file. It has a build stage that:

  1. adds the OpenFaaS fwatchdog component
  2. copies the sources of our n_queens function and builds a binary from it

The second section of the docker file actually creates the final docker image. It copies fwatchdog and n_queens binaries from the build stage.

Now build the Docker image and push it to DockerHub.

$ ll total 16 drwxr-xr-x 4 sebastian staff 128 Feb 15 18:40 . drwxr-xr-x 3 sebastian staff 96 Feb 15 18:29 .. -rw-r--r-- 1 sebastian staff 568 Feb 15 18:40 Dockerfile -rw-r--r-- 1 sebastian staff 2321 Feb 15 18:29 main.go $ docker build -t banzaicloud/nqueens:1.0-dev . $ docker push banzaicloud/nqueens:1.0-dev 

Deploy a Function to OpenFaaS using the UI

Open the OpenFaaS Portal -> Deploy a New Function -> Manual

Docker image: banzaicloud/nqueens:1.0-dev

Function name: nqueens

Click Deploy.

Once our nqueens function is deployed it can be invoked from the OpenFaaS Portal or using curl. (e.g. curl -X POST -d “15” http://{{public_endpoint_host}}/function/nqueens)

Deploy a Function to OpenFaaS using the faas-cli command line tool

Functions can be deployed not only through the OpenFaaS portal but also using the faas-cli command line tool (which has a rich set of options compared to the UI). Let’s see through an example how faas-cli can be used.

We built a aws-cli docker image banzaicloud/openfaas-aws-cli:1.0 based on this blogpost.

To deploy the aws-cli function run:

faas-cli deploy --name aws-cli --image banzaicloud/openfaas-aws-cli:1.0 --env AWS_ACCESS_KEY_ID={{replace_your-access-key}} --env AWS_SECRET_ACCESS_KEY={{replace_your-secret-key}} --gateway http://{{public_endpoint_host}}/ 

The deployed function can be invoked either from the OpenFaaS Portal or curl or faas-cli command: e.g.:

curl -d "ec2 describe-instances --region eu-west-1" http://{{public_endpoint_host}}/function/aws-cli 
faas-cli invoke aws-cli --gateway http://{{public_endpoint_host}}/ 

The next post in the series will be about Kubeless and how that compares to OpenFaaS and also we will talk about the interface of invoking functions – and an automated way of adding function invocations to Pipeline’s CI/CD workflow.

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