openfaas-http-echo

• openfaas-http-echo
• Introduction
• Prerequisites
  • Install OpenFaaS
  • OpenFaaS Installation on Kubernetes
  • Access the OpenFaaS Infra
  • Deploy Grafana for Function Metrics
• Deploy Sample Functions to OpenFaaS
• Deploy the GoLang based HTTP Echo Function
• References
• Maintainer

Introduction

Sample OpenFaaS App on K8s which Reflects/Echo's the HTTP Data based on GoLang for Testing

Prerequisites

• Working Kubernetes 1.11+ Cluster

Install OpenFaaS

Install OpenFaaS CLI on the host

curl -sL https://cli.openfaas.com | sudo sh

I have used Arkade to install OpenFaaS on local Kubernetes Cluster, to install Arkade CLI

curl -SLsf https://dl.get-arkade.dev/ | sudo sh

OpenFaaS Installation on Kubernetes

Make sure that the host on which you are going to run the following Arkade command has the correct AuthN/AuthZ setup with the Kubernetes Cluster.

arkade install openfaas
<output snipped>

To validate the components on K8s Cluster

kubectl get pods -n openfaas
NAMESPACE     NAME                                       READY   STATUS    RESTARTS   AGE
openfaas      alertmanager-57bd4559d7-59nxz              1/1     Running   0          3m33s
openfaas      basic-auth-plugin-7d4956689b-68wh6         1/1     Running   0          3m33s
openfaas      faas-idler-b85f98fb7-lcx7r                 1/1     Running   2          3m33s
openfaas      gateway-59b667b794-crncr                   2/2     Running   0          3m33s
openfaas      nats-5cd4dff7c8-8gkl9                      1/1     Running   0          3m33s
openfaas      prometheus-bcc84d4d5-btxrc                 1/1     Running   0          3m33s
openfaas      queue-worker-6cb888d49c-2qh6q              1/1     Running   3          3m33s

Login to OpenFaaS CLI

PASSWORD=$(kubectl get secret -n openfaas basic-auth -o jsonpath="{.data.basic-auth-password}" | base64 --decode; echo)
echo -n $PASSWORD | faas-cli login --username admin --password-stdin

Access the OpenFaaS Infra

To deploy the gateway

kubectl rollout status -n openfaas deploy/gateway

To portforward to access OpenFaaS UI

kubectl port-forward -n openfaas svc/gateway 8080:8080

The service can also be exposed over NodePort or LoadBalancer depending upon the infrastructure.

OpenFaaS UI can be accessed at http://127.0.0.1:8080/ui/ on localhost

Change the prometheus to be exported over NodePort/LoadBalancer service types to access it outside.

kubectl get svc -n openfaas
NAME                TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
alertmanager        ClusterIP   10.105.14.181    <none>        9093/TCP         19m
basic-auth-plugin   ClusterIP   10.108.176.255   <none>        8080/TCP         19m
gateway             ClusterIP   10.98.25.123     <none>        8080/TCP         19m
gateway-external    NodePort    10.104.83.141    <none>        8080:31112/TCP   19m
nats                ClusterIP   10.102.252.133   <none>        4222/TCP         19m
prometheus          NodePort    10.102.39.112    <none>        9090:32333/TCP   19m

Deploy Grafana for Function Metrics

Deploy Grafana to connect to Prometheus to display the function metrics.

kubectl create deployment grafana --image=docker.io/grafana/grafana -n openfaas

Expose the Grafana service over NodePort/LoadBalancer depending upon your infrastructure, since I am using Single Node K8s cluster, I will use NodePort to expose Grafana.

kubectl expose deployment grafana --type=NodePort --port=80 --target-port=3000 --protocol=TCP -n openfaas

Validate the Grafana and Prometheus Pods and Services

kubectl get pods -n openfaas | grep -E 'grafana|prometheus'; kubectl get svc -n openfaas | grep -E 'grafana|prometheus'
grafana-7d6646ffc-xn9bs              1/1     Running   0          12m
prometheus-bcc84d4d5-btxrc           1/1     Running   0          9h
grafana             NodePort    10.102.28.74     <none>        80:31035/TCP     87s
prometheus          NodePort    10.102.39.112    <none>        9090:32333/TCP   9h

Note the NodePort ports for access, to keep them constant one can create yaml's definitions to apply.

Access the dashboard and set the password. Default user/pass is admin/admin.

Configure the Grafana to point to Prometheus Data Source in the namespace.

Import the OpenFaaS Dashboard - https://grafana.com/grafana/dashboards/3526 & https://grafana.com/grafana/dashboards/3434

Grafana Dashboard -

Deploy Sample Functions to OpenFaaS

For CLI, set the URL

export OPENFAAS_URL=http://127.0.0.1:31112

Pickup the port from NodePort service type. Login to the CLI first.

Deploy the sample NodeInfo app from OpenFaaS Store

faas-cli store deploy NodeInfo
WARNING! Communication is not secure, please consider using HTTPS. Letsencrypt.org offers free SSL/TLS certificates.

Deployed. 202 Accepted.
URL: http://127.0.0.1:8080/function/nodeinfo

This app can be seen in the UI & App Response can be observed on the call.

Deploy the GoLang based HTTP Echo Function

Inside the functions directory, initialize the function with pulling the template

faas template store pull golang-http
faas new --lang golang-http go-http-echo

Build the Docker Image Locally. Since I am running a single node cluster, the docker image built will be locally present, for multi-node cluster or proper deployments make sure to push the image to Registry or DockerHub with proper prerequisites of login creds. You can use "faas-cli push" to push to remote repo.

cd functions
faas-cli build -f go-http-echo.yml

docker images
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
subodhp/go-http-echo                         latest              0de669751925        2 minutes ago       25.1MB
<output snipped>

Login to Registry, in my case I am using public DockerHub Repo.

docker login
<perform successful login>

faas-cli push -f go-http-echo.yml 
[0] > Pushing go-http-echo [subodhp/go-http-echo:latest].
The push refers to repository [docker.io/subodhp/go-http-echo]
<output snipped>

Deploy the function.

faas-cli deploy -f go-http-echo.yml 
Deploying: go-http-echo.
WARNING! Communication is not secure, please consider using HTTPS. Letsencrypt.org offers free SSL/TLS certificates.

Deployed. 202 Accepted.
URL: http://127.0.0.1:8080/function/go-http-echo.openfaas-fn

Invoke the function via CLI.

echo -n "test" | faas-cli invoke go-http-echo

To remove the deployed function.

faas-cli remove -f go-http-echo.yml

Output of the function which includes headers from the requestor. It can be seen that for various clients, the fields are detected and responded by the function.

Using OpenFaaS CLI -

echo -n "test" | faas-cli invoke go-http-echo
Handling connection for 8080
Hello world, input was: test
Headers Received from Caller: 
Accept-Encoding: gzip
Content-Type: text/plain
X-Forwarded-For: 127.0.0.1:55340
X-Forwarded-Host: 127.0.0.1:8080
User-Agent: Go-http-client/1.1

Access the OpenFaaS Gateway over NodePort for External Access

echo -n "test" | faas-cli invoke --gateway http://127.0.0.1:31112 go-http-echo

The port 31112 may vary depending upon your gateway-external service port.

Using CURL -

curl -d test -X POST -H "test-header: subodh" http://127.0.0.1:8080/function/go-http-echo
Handling connection for 8080
Hello world, input was: test
Headers Received from Caller: 
User-Agent: curl/7.68.0
Accept: */*
Accept-Encoding: gzip
Content-Type: application/x-www-form-urlencoded
Test-Header: subodh
X-Forwarded-For: 127.0.0.1:59804
X-Forwarded-Host: 127.0.0.1:8080

Invocation via UI -

Success!

References

• https://docs.openfaas.com/deployment/kubernetes/
• https://hub.docker.com/repository/docker/subodhp/go-http-echo
• https://blog.alexellis.io/serverless-golang-with-openfaas/
• https://github.com/openfaas-incubator/golang-http-template

Maintainer

Subodh at subodhpachghare@gmail.com