K8.Jinja.Templating

cloudbuild.tf

############################################################################################
# A sample Terraform file that creates the cloud build trigger.
############################################################################################
resource "google_cloudbuild_trigger" "develop_trigger" {
  description = "[DEVELOP] Build develop branch"
  filename = "cloudbuild.yaml"
  trigger_template {
    branch_name = "^develop$"
    repo_name = "houston"
  }
  substitutions = {
    _ENVR = "dev" 
    _PROVISION_WEBUI = "true"
    _CLOUDSDK_COMPUTE_REGION = var.region
    _CLOUDSDK_COMPUTE_ZONE = var.zone
    _CLOUDSDK_CONTAINER_CLUSTER = var.gke_name
  }
}

variable "region" {
  type    = "string"
  default = "xxxxx"
}

variable "zone" {
  type = "string"
  default = "xxxxxx"
}

variable "gke_name" {
  default = "houston-launchpad"
}

cloudbuild.yaml

############################################################################################
# A sample Cloud Build YAML file thay shows 
############################################################################################
steps:
# Build Web App container 
- name: 'gcr.io/cloud-builders/docker'
  args: ['build', '-f', 'Dockerfile',
         '--build-arg', '_ENVR=$_ENVR',
         '-t', 'eu.gcr.io/$PROJECT_ID/houston-web-app:$SHORT_SHA',
         '.']
  dir: 'web-app'
  
 # Push container 
- name: 'gcr.io/cloud-builders/docker'
  args: ['push', 'eu.gcr.io/$PROJECT_ID/houston-web-app:$SHORT_SHA']
  
# Run the Jinja Template on all YAML file inside the 'deployment/kubernetes' directory
# Using a public container from docker hub by user: pinterb
- name: 'pinterb/jinja2'
  entrypoint: 'python'
  args: ['../scripts/k8_template_eval.py']
  dir: 'deployment/kubernetes'
  env:
    - '_ENVR=$_ENVR'
    - '_APP_VERSION=$SHORT_SHA'
    - '_PROVISION_WEBUI=$_PROVISION_WEBUI'

# Apply K8 Deployments
- name: 'gcr.io/cloud-builders/kubectl'
  args: ['apply', '-f', 'deployment/kubernetes/deployments']
  env:
    - 'CLOUDSDK_COMPUTE_ZONE=$_CLOUDSDK_COMPUTE_ZONE'
    - 'CLOUDSDK_CONTAINER_CLUSTER=$_CLOUDSDK_CONTAINER_CLUSTER'

k8_jinja_templating.py

#!/usr/local/bin/python3

# Template Parser for YAML files
#
# Reads all of the YAML file in the directory it was run in and parses them with Jinja2
# All variables are taken from the environment


import os
from os.path import join

from jinja2 import Environment, FileSystemLoader


def get_yaml_files(dirName='.'):
    file_list = list()
    for (dirpath, dirnames, filenames) in os.walk(dirName):
        file_list += [join(dirpath, file) for file in filenames if (file.endswith('.yaml') or file.endswith('.yml'))]
    return file_list


def parse_file(file):
    template = jinja_env.get_template(file)
    template.stream(os.environ).dump(file)


def parse_dir(dirName='.'):
    for f in get_yaml_files(dirName=dirName):
        print('Parsing file:  {f}'.format(f=f))
        parse_file(f)


if __name__ == '__main__':
    config_path = '.'
    jinja_env = Environment(loader=FileSystemLoader(config_path))
    parse_dir(dirName=config_path)

web-app-deployment.yaml

############################################################################################
# A sample Kubernetes deployment that shows how the Jinja template is used 
############################################################################################
{% if  _PROVISION_WEBUI == "true" %}
kind: Deployment
apiVersion: apps/v1
metadata:
  name: web-app-deployment
  namespace: {{ _ENVR }}
  labels:
    app: web-app
    appVersion: '{{ _APP_VERSION }}'
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web-app
  template:
    metadata:
      labels:
        app: web-app
    spec:
      containers:
      - name: web-app
        image: 'eu.gcr.io/{{ PROJECT_ID }}/houston-web-app:{{ _APP_VERSION }}'
        imagePullPolicy: Always
        ports:
        - containerPort: 80
        env:
          - name: NODE_ENV
            value: {{ 'production' if _ENVR == 'prod' else 'development'  }}

{% endif %}