Add ResolvePodSpec to podspec.go and move the related utilities to podspec_helper

[daisy-ycguo]

Description

It's a refactor PR. The goal is to add a method

func (p *PodSpecFlags) ResolvePodSpec(podSpec *corev1.PodSpec, cmd *cobra.Command) error

in flags/podspec.go so that the logic to resolve a PodSpec from flags can be used by both service commands group and ContainerSource commands group.

This PR demonstrates how PodSpecFlags.ResolvePodSpec is used in service commands. PR #1016 demonstrates how PodSpecFlags and PodSpecFlags.ResolvePodSpec is used in container source commands.

Changes

• Add a method ResolvePodSpec in flags/podspec.go
• Move podspec related utilities from serving/config_changes.go to flags/podspec_helper.go
• Move two common functions from serving/config_changes.go to utils/corev1_helper.go
• Refactor service commands to adopt the changes

Reference

Refer to PR #1016 and see how PodSpecFlags.ResolvePodSpec is used in container source commands group.

[maximilien]

Thanks for doing this.
/test pull-knative-client-integration-tests

[daisy-ycguo]

/test pull-knative-client-integration-tests-latest-release

[navidshaikh]

/retest

[daisy-ycguo]

I will rebase it when #1068 gets merged. Let's see if the lint test could pass.

[daisy-ycguo]

@maximilien @rhuss @navidshaikh @dsimansk I think this one is ready for review. Will you take a look ? Thank you.

[maximilien]

As per meeting yesterday, this is good to go, right @navidshaikh ?

LGTM

[navidshaikh]

lgtm, please remove the commented code and add a CHANGELOG entry, we should be good to merge then.

[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-knative-client-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/kn/commands/service/configuration_edit_flags.go	83.5%	87.5%	4.0
pkg/kn/flags/podspec.go	97.6%	78.4%	-19.2
pkg/kn/flags/podspec_helper.go	Do not exist	77.9%
pkg/serving/config_changes.go	76.2%	85.0%	8.8
pkg/util/corev1_helper.go	Do not exist	70.8%

[navidshaikh]

/lgtm
/approve

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: daisy-ycguo, maximilien, navidshaikh

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