Make tiers "mergeable" when providing multiple value.yaml at helm install

[micgoe]

Problems / Request

My client runs multiple pega plattform installations in multiple environments. In order to maintain a clean deployment configuration for each plattform installation and environments we install the pega-helm-chart/pega by providing the helm install with multiple values.yaml. At least one dev-common.yaml and an pega-plattform specific yaml dev-pega-1.yaml. The one provided latest overwrites properties of the previous. The frustration lies in the nature on how lists are overwritten/merged. In this specific matter it applies to the tier list. When providing a common configuration for the web tier (common.yaml) which is refined by additional pega-plattform specific web tier configuration (dev-pega-1.yaml) the entire web node tier item is overwritten and not merged.

Example:

Input:

dev-common.yaml

...
tier:
- name: "web"
  nodeType: "WebUser"
  service:
    annotation:
      something: "some-common-annotation-for-all-web-nodes-in-dev"
    httpEnabled: false
    port: 80
    targetPort: 8080
...

dev-pega-1.yaml

...
tier:
- name: "web"
    ingress:
      domain: "dev-pega-1.example.com" # specific for each plattform
...

Output:

tier:
  name: "web"
    nodeType: "WebUser"
  
    requestor:
      passivationTimeSec: 900
  
    service:
      # annotation is missing
      httpEnabled: true
      port: 80
      targetPort: 8080
      ... # other defaults defined in charts values.yaml
    ingress:
      domain: "dev-pega-1.example.com" # specific for each plattform

Example for configuration which might be the same across pega-plattforms in the same environment:

• custom proxy configuration (tier[web].custom.env)
• custom logging configuration (tier[web].custom.XY.xml)
• web nodes port (tier[web].service.port, tier[web].service.targetPort)

Solution:

Switch from using a list for tier to using key-value. This would allow helm to clearly identify objects and would result in merging them together.

Ex:

tier:
  web:
    nodeType: "WebUser"
  
    requestor:
      passivationTimeSec: 900
  
    service:
      annotation:
        something: "some-common-annotation-for-all-web-nodes-in-dev"
      httpEnabled: true
      port: 80
      targetPort: 8080
      ... # other defaults defined in charts values.yaml
    ingress:
      domain: "dev-pega-1.example.com" # specific for each plattform

Alternatives Not following a clean common/specific value file separation model. Right now we define all the tiers in the pega plattform specific yaml (dev-pega-1.yaml) which is not a clean and error prone solution

Additional context Add any other context or screenshots about the feature request here.

Debugging of the resulting values applied can be done by