use data from ConfigMap with some hardcoded modifications

[edmondsw]

We have a ConfigMap with some data in it, and I want to pull that data into another ConfigMap but with a few changes to add or override some things.

I think we should be able to use overrideStrategy for this, but it currently seems to expect the override data to come from another ConfigMap, whereas I want to be able to hardcode the data I want to add/override into the mtp. To do this we would need to be able to specify a block of json or yaml instead of a configMapKeyRef

Here's an example of one of the things I tried that did not work:

apiVersion: deploy.razee.io/v1alpha2
kind: MustacheTemplate
metadata:
  name: test-mtp-template
  namespace: mynamespace
spec:
  templateEngine: handlebars
  env:
  - name: foo
    valueFrom:
      configMapKeyRef:
        name: common-config
        key: foo
        type: jsonString
  - name: foo
    overrideStrategy: merge
    value: '{"bar": "something"}'
  strTemplates:
  - |
    apiVersion: v1
    kind: ConfigMap
    metadata:
      name: foo-cm
      namespace: mynamespace
    data:
      foo: "{{{ foo }}}"

[alewitt2]

with the latest version of MTP https://github.com/razee-io/MustacheTemplate/releases/tag/2.1.0, i think we have a workaround for you.

instead of using value, use valueFrom, but point at some non-existant configmap. You will also need to define a default value. The only side effect from this work around, is there will be a warning message that says "couldnt find your value, we are using the default instead"

ex:

apiVersion: deploy.razee.io/v1alpha2
kind: MustacheTemplate
metadata:
  name: test-mtp-template
  namespace: mynamespace
spec:
  templateEngine: handlebars
  env:
  - name: foo
    valueFrom:
      configMapKeyRef:
        name: common-config
        key: foo
        type: json
  - name: foo
    overrideStrategy: merge
    default: '{"bar": "something"}'
    valueFrom:
      configMapKeyRef:
        name: this-config-doesnt-exist
        key: you-cant-find-me
        type: json
  strTemplates:
  - |
    apiVersion: v1
    kind: ConfigMap
    metadata:
      name: foo-cm
      namespace: mynamespace
    data:
      foo: "{{{ foo }}}"

i'll leave this issue open, as it probably makes sense to support typecasting a plain value at some point.

[alewitt2]

for future reference..
i think this will involve adding a type field at the same level as value in the schema, and then calling typeCast on env.value with said type, before doing the short circuit return of value

  #processEnv(envs) {
    return Promise.all(envs.map(async (env) => {
      if (env.value) {
        if (env.type) env.value = typeCast(env.value, env.type);
        return env;
      }
      ...
    }
  }