Add first class support for `/etc/pip.conf` in the values.yaml for Workbench and Connect

[SamEdwardes]

It is a common task for admins to customize pip settings, particularly the index-url.

Option 1 - first-class support

For example:

Workbench

# values.yaml
config:
  session:
    repos.conf:
      RSPM: https://packagemanager.rstudio.com/cran/__linux__/jammy/latest
      CRAN: https://packagemanager.rstudio.com/cran/__linux__/jammy/latest
    # pip.conf should be written to /etc/pip.conf
    pip.conf: |
        [global]
        index-url = https://pypi.org/simple

Connect

I am less sure on what the correct approach for Connect should be, since current config key in the values.yaml maps directly to Connect config file.

Option 2 - document examples

Workbench

# values.yaml
extraObjects:
  - apiVersion: v1
    kind: ConfigMap
    metadata:
      name: pip-config-workbench
    data:
      pip.conf: |
        [global]
        index-url = https://pypi.org/simple

launcher:
  enabled: true
  useTemplates: true
  templateValues:
    pod:
      volumes:
        - name: pip-config-volume
          configMap:
            name: pip-config-workbench
      volumeMounts:
        - mountPath: /etc/pip.conf
          name: pip-config-volume
          subPath: pip.conf

Connect

# values.yaml
extraObjects:
  - apiVersion: v1
    kind: ConfigMap
    metadata:
      name: pip-config-connect
    data:
      pip.conf: |
        [global]
        index-url = https://pypi.org/simple

launcher:
  enabled: true
  useTemplates: true
  templateValues:
    pod:
      volumes:
        - name: pip-config-volume
          configMap:
            name: pip-config-connect
      volumeMounts:
        - mountPath: /etc/pip.conf
          name: pip-config-volume
          subPath: pip.conf

[colearendt]

This is done for Workbench in #407 (but it requires not using job-json-overrides / using templates)

[dbkegley]

This is on our radar for Connect but we are unlikely to solve it in the helm chart. More likely this will be a configuration option in Connect eventually.