# knative (serverless)

knative examples

https://github.com/kontainapp/guide-examples/tree/master/examples/knative/basics

This section shows how we can use Kontain in a serverless or funtions as a service environment to secure Functions using hardware virtualization based workload isolation.

We can use the same guide-examples gihub repo to see the files associated with this example as linked to above.

# Description

This describes how to use Kontain with KNative. It shows you how to:

install KNative in a kind cluster
and install Kontain
deploy and run a KNative service that uses a secure Kontain Container to run the function

# Azure AKS with knative and kontain

Here are instructions to install knative and kontain on an AKS cluster.

# Starting a knative kind cluster with Kontain

# Installing knative kind quickstart plugins on your local desktop

Note that this has to be done only once. This also assumes that you have the pre-requisites, Docker and kind kubernetes utility along with kubectl already installed.

Also, please note that this has to be done on an OS that satisfies the pre-requisites for Kontain as shown earlier.

# you will need to clone the examples repo
$ git clone https://github.com/kontainapp/guide-examples.git
$ cd examples/knative/basics

# install the knative plugins for kind
$ make knativecluster-plugins-install

# Starting the kind cluster with knative and kontain installed

$ make knativekindcluster-up

# Working with KNative Kontain-enabled services

# Deploy the service

The service manifest file: hello-kontain-svc.yml

# install the Kontain-enabled function as a service
$ kubectl apply -f hello-kontain-svc.yml 

# check the service
$ kn service list
NAME            URL                                               LATEST                AGE   CONDITIONS   READY   REASON
hello-kontain   http://hello-kontain.default.127.0.0.1.sslip.io   hello-kontain-00001   27s   3 OK / 3     True

# Invoke the service

$ curl $(kn service describe hello-kontain -o url)
Hello World!

# Deploy an update to the service with a revision

The revised service manifest file:

hello-kontain-svc-revised.yml

$ kubectl apply -f hello-kontain-svc-revised.yml

$ curl $(kn service describe hello-kontain -o url)
Hello knative!

# Check for traffic being routed to current revision

$ kn revisions list
NAME                  SERVICE         TRAFFIC   TAGS   GENERATION   AGE     CONDITIONS   READY   REASON
hello-kontain-00002   hello-kontain   100%             2            5m16s   3 OK / 4     True    
hello-kontain-00001   hello-kontain                    1            34m     3 OK / 4     True

# Canary service deployment: 50% to revision

The service manifest wwith the traffic split direct for revisions:

hello-kontain-svc-traffic-split.yml

$ kubectl apply -f hello-kontain-svc-traffic-split.yml

# check the traffic split
$ kn revisions list
NAME                  SERVICE         TRAFFIC   TAGS   GENERATION   AGE   CONDITIONS   READY   REASON
hello-kontain-00002   hello-kontain   50%              2            20m   4 OK / 4     True    
hello-kontain-00001   hello-kontain   50%              1            49m   4 OK / 4     True

$ echo checking the traffic split implementation by invoking service 20 times...
$ for i in {1..20}; do curl $(kn service describe hello-kontain -o url); done76s
Hello World!
Hello Kontain!
Hello World!
Hello Kontain!
...
...

# Working with KNative Kontain-enabled Spring Boot service

# From scale to zero state to starting up to respond to a request

At first, we will show the regular spring boot knative service running, and replying to a request from scale to zero state.

# deploy the knative spring boot hello service
$ kubectl apply -f springboothello-kontain.yml

# watch it getting deployed
$ kubectl get po -w

# see list of kontain-enabled services
$ kn service list
NAME                             URL                                                                LATEST                                 AGE     CONDITIONS   READY   REASON
hello-kontain                    http://hello-kontain.default.127.0.0.1.sslip.io                    hello-kontain-00001                    42m     3 OK / 3     True
hello-kontain-spring-boot        http://hello-kontain-spring-boot.default.127.0.0.1.sslip.io        hello-kontain-spring-boot-00001        19m     3 OK / 3     True

# sleep for a few seconds for the pod to be terminated to test scale to zero and up
$ sleep 10

# invoke the spring boot service
$ curl $(kn service describe hello-kontain-spring-boot -o url)
Hello from Kontain!

# Note that it takes about 8 seconds for it to respond

# From scale to zero state to response, using a Snapshot of the Spring Boot service

Now, we will show the same spring boot knative service in scale to zero state, and then starting up to reply to a request from scale to zero state.

# deploy the knative spring boot hello service
$ kubectl apply -f springboothello-kontain-snap.yml

# watch it getting deployed
$ kubectl get po -w

# see list of kontain-enabled services
$ kn service list
NAME                             URL                                                                LATEST                                 AGE     CONDITIONS   READY   REASON
hello-kontain                    http://hello-kontain.default.127.0.0.1.sslip.io                    hello-kontain-00001                    42m     3 OK / 3     True
hello-kontain-spring-boot        http://hello-kontain-spring-boot.default.127.0.0.1.sslip.io        hello-kontain-spring-boot-00001        19m     3 OK / 3     True
hello-kontain-spring-boot-snap   http://hello-kontain-spring-boot-snap.default.127.0.0.1.sslip.io   hello-kontain-spring-boot-snap-00001   9m53s   3 OK / 3     True

# sleep for a few seconds for the pod to be terminated to test scale to zero and up
$ sleep 10

# invoke the spring boot service
$ curl $(kn service describe hello-kontain-spring-boot-snap -o url)
Hello from Kontain!

# Note that it takes only about 3 seconds for it to respond
# - most of it is spent in starting up the container, for Kubernetes to get its liveness and readiness probe ready etc.