Updating Values in Yaml File Dynamically

update.py

#!/usr/bin/env python3
# This is a simple way to edit/add values to a k8s configuration yaml file. 
# This can be handy to test a change or to create a changes based on a policy outside the k8s stack.

import yaml

# I used yaml file available here https://raw.githubusercontent.com/kubernetes/website/main/content/en/examples/controllers/nginx-deployment.yaml
with open(f"deployment.yaml", "r") as stream:
    try:
        yaml_file = yaml.safe_load(stream)
    except yaml.YAMLError as exc:
        print(exc)

# You can do multiple types of updates.
# Change a value directly
yaml_file["spec"]["replicas"] = 5 # You can use any source for this input

# Change value inside a list
for container in yaml_file["spec"]["template"]["spec"]["containers"]:
    if container["name"] == "nginx":    
        container["image"] = "nginx:latest"

# Add Values specific to this trial
yaml_file["spec"]["template"]["spec"]["containers"][0]["env"] = [{"name":"PASSWORD", "value": 'ADMIN'}]

print(yaml.dump(yaml_file))

# To run
# python3 gist.py | kubectl apply -f -

# To remove deployment
# python3 gist.py | kubectl delete -f -