Hyperledger Fabric’s Application Development Practices¶

Certain practices can help the developer create applications which are one click deployable on Zeeve. They are:-

For packaging your product to be automated by Zeeve, you will need to dockerize your project’s services by creating Dockerfiles for them.
```
FROM node:8.9.0

WORKDIR /balance-transfer

COPY . .
ENV PORT=4000
RUN npm install
CMD node app
```
Make use of network-config.yaml (connections profiles) and org.yaml (if required) for all blockchain related configurations. At the time of deployment for a network, Zeeve creates these files and allows the developer to download them along with the other artifacts. You can consider this file to develop your applications. All other application configs should be part of the Docker image itself.
Create a .env file containing an array of domain prefixes corrosponding to Ingress resource definitions. The syntax should be of the form: ("<domain_prefix_1>:<ingress_resource_name_1>" "<domain_prefix_2>:<ingress_resource_name_2> ...")
```
EXT_EXPOSED_SERVICES=("balancetranfer:balance-transfer-ingress")
```
Create a docker-compose-build.yaml file for creating images of all services that your application requires. This will help Zeeve create relevant images, push them to the container-registry and later use them.
- Each service definition whose container image would be created needs to have an image keyword, the associated value needs to same as that of image name (Deployment.contianers.spec.containers.image) in k8_application.yaml.template.
```
version: "2.0"

services:
  balance-transfer:
    build:
      context: .
      dockerfile: Dockerfile
    image: balance-transfer:latest
    container_name: balance-transfer-default
    ports:
      - '4000:4000'
    command: |
      bash -c "PORT=4000 node app"
    restart: always
```

Create a yaml file k8_application.yaml.template and keep it at your project’s root folder. The file needs to keep the following points in account:-

The image name for containers needs to adhere to the guideline outlined in the step above.
Define an imagePullSecrets named container-registry-cred. Creation and updation of this secret is handled by Zeeve, but the definition is developers responsibility.
For mounting relevant crypto data and channel artifacts in a deployment, Zeeve will create secrets and mount them on /crypto-data path. The deployment/s on which this mounting takes place is identified by special character string @@replace_my_crypto_artifacts@@.
Host for each Ingress resource will be an amalgamation of information specified in .env file and domain assigned to your Kubernetes cluster.
Take special care to mount relevant persistent volumes as pods will be recreated whenever there is an application update.

apiVersion: v1
kind: Service
metadata:
  name: balance-transfer-svc
spec:
  type: ClusterIP
  ports:
    - port: 4000
      targetPort: 4000
      protocol: TCP
  selector:
    name: balance-transfer-dep

 ---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: balance-transfer-dep
spec:
  replicas: 1
  selector:
    matchLabels:
      name: balance-transfer
  template:
    metadata:
      labels:
        name: balance-transfer
    spec:
      volumes:
        #- name: balance-transfer-data
        #  persistentVolumeClaim:
        #    claimName: balance-transfer-data-pvc
            @@replace_my_crypto_artifacts@@
      imagePullSecrets:
      - name: container-registry-cred
      containers:
        - name: balance-transfer
          image: balance-transfer:12
          imagePullPolicy: Always
          ports:
            - containerPort: 4000
              protocol: TCP
          #livenessProbe:
          #  httpGet:
          #    path: /
          #    port: 4000
          command:
            - bash
            - -c
            - |
              echo "installing GO" 
              cd /usr/local
              curl -O https://dl.google.com/go/go1.10.3.linux-amd64.tar.gz
              tar -xvf go1.10.3.linux-amd64.tar.gz
              echo "export PATH=$PATH:/usr/local/go/bin" >> /root/.bashrc
              source /root/.bashrc

              echo "configuring application"
              mkdir /application
              cd /application
              cp -r /balance-transfer/* ./
              cp -Lr /crypto-data/* ./artifacts/
              #npm install
              node app
          volumeMounts:
            #- mountPath: /application
            #  name: balance-transfer-data
              @@replace_my_crypto_artifacts@@
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: balance-transfer-data-pvc
spec:
  accessModes:
    - "ReadWriteOnce"
  resources:
    requests:
      storage: "5Gi"

---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: balance-transfer-ingress
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/backend-protocol: "http"
spec:
  rules:
    - host: 
      http:
        paths:
        - backend:
            serviceName: balance-transfer-svc
            servicePort: 4000

While uploading the project attach some supporting documents to explain the organisation names and other details that shall be put while creating networks for the product. These documents will help users to create and deploy networks and products on their own.