Connecting an application on Kyma with an on-premise system

[MarcelloUrbani]

The latest version of ActiveControl's UI is distributed as a container.

This allows us to run the same artifact in many containerised environment using a single, like docker, btp cloudfoundry, btp kyma and many others.

When running in BTP we usually need to connect to on-premise systems with cloud connector, which is trivial and well documented in cloudfoundry runtime.

Has been more of a journey in Kyma, partly because I know next to nothing about it or kubernetes, partly because there's much fewer knowledge about it in the wild, and I found parts of the documentation a bit confusing (i.e. referring to menu entries who were renamed or need some configuration to appear)

This is basically a sumbed-down version of this blog from jamie.cawley and related documentation, with additional notes/tips from me.

Will definitely be less accurate, but might help other novices.

Step 1: get the application on Kyma - without cloud connector

This was trivial.

Just download the kubernetes configuration from that link in your btp configuration:

install kubectl and copy the downloaded file to yout kubernetes cpnfiguration:

# for linux/bash

cp ~/Downloads/kubeconfig.yaml ~/.kube/config

Create a deployment for your application, including a namespace for convenience.

This is a YAML file with many resources separated by a single line containing --- , will include a simplified example later.

Looks like this:

and as long as the application only needs to talk with cloud services and other Kubernetes resources we're hunky dory

But I usually need to connect to locked down, on premises systems.

Step 2: Cloud connector

This gets significantly more complex. On my deployment file I only need to add a connectivity proxy service and binding. But I also need:

• api gateway instance on kyma-service namespace (I believe Kyma magically created this for me)


• btp-operator instance on kyma-service namespace


• connectivity service on cloudfoundry (I believe Kyma magically created this for me)


• sap cloud connector instance on my network (running on my laptop)

The full diagram looks like this:

I found the sample code and instructions in the connectivity-proxy folder of the Kyma Runtime Extension Sample repo pretty easy to understand, except the bits on setting up things in kyma

 

Setting up cloud connector

This works as usual as long as you leave the location ID blank. I didn't figure out how to use a non-blank one

Also, I didn't try principal propagation (yet)

Enabling a Kyma module

The documentation explains how to do that in the Kyma console, but refers to menu entries I can't find

Luckily also explains how to do it with the CLI, and this did the trick:

kyma alpha enable module btp-operator -c fast --kyma-name default --wait

Enabling it took longer than expected and I got a timeout error in CLI, but finally found the entry in kyma dashboard and just waited there

Finally I was able to deploy  the application and connect to it

# deploy the application

kubectl apply -f ./activecontrol-cloudconn.yaml



# getthe application url (using the namespace created in the yaml file)

kubectl get virtualservices --namespace activecontrol-cloudconn



# get the application logs as they're created

kubectl logs -l app=activecontrolcc --namespace activecontrol-cloudconn -f

This will create an application in kyma and an instance and binding in btp:

... and I can now log in via my sap cloud connector:

PS: at some point stopped working, had to kill the connectivity pod

kubectl delete pod connectivity-proxy-0 -n kyma-system

Sample configuration

This is my full YAML fine, for reference

kind: Namespace

apiVersion: v1

metadata:

  name: activecontrol-cloudconn

  labels:

    name: activecontrol-cloudconn

    istio-injection: enabled

---

apiVersion: services.cloud.sap.com/v1

kind: ServiceInstance

metadata:

  name: connectivity-proxy

  namespace: activecontrol-cloudconn

spec:

  serviceOfferingName: connectivity

  servicePlanName: connectivity_proxy

  externalName: connectivity-proxy

---

apiVersion: services.cloud.sap.com/v1

kind: ServiceBinding

metadata:

  name: ccbinding

  namespace: activecontrol-cloudconn

spec:

  serviceInstanceName: connectivity-proxy

  externalName: ccbinding

  secretName: ccbinding

---

apiVersion: apps/v1

kind: Deployment

metadata:

  name: activecontrolcc

  namespace: activecontrol-cloudconn

  labels:

    app: activecontrolcc

spec:

  replicas: 1

  selector:

    matchLabels:

      app: activecontrolcc

  template:

    metadata:

      labels:

        app: activecontrolcc

    spec:

      containers:

        - name: activecontrolgui

          image: dockerregistry.basistechnologies.info/activecontrolgui:AC-992-add-proxy-support

          imagePullPolicy: Always

          resources: 

            limits:

              cpu: 1000m

              memory: 1Gi          

          ports:

            - name: http

              containerPort: 9200

          env:

            - name: SAPSYSTEM_URI_ACD

              value: "http://acd:8000"

            - name: BTIWP_PROXY

              value: '{"host": "connectivity-proxy.kyma-system.svc.cluster.local","port": 20003 }'

---

apiVersion: v1

kind: Service

metadata:

  name: activecontrolcc

  namespace: activecontrol-cloudconn

  labels:

    app: activecontrolcc

spec:

  ports:

    - name: http

      port: 9200

  selector:

    app: activecontrolcc

---

apiVersion: gateway.kyma-project.io/v1beta1

kind: APIRule

metadata:

  name: activecontrolcc

  namespace: activecontrol-cloudconn

spec:

  gateway: kyma-gateway.kyma-system.svc.cluster.local

  host: activecontrolcc

  service:

    name: activecontrolcc

    port: 9200

  rules:

    - path: /.*

      accessStrategies:

        - config: {}

          handler: noop

      methods: ["DELETE","HEAD","GET","PATCH","POST","PUT"]