Fix cronjob sample bug

[whynowy]

Use real message_dumper image instead of ko image path.

Fixes #813

Used ko image path in the spec however the installation command in README.rd was "kubectl apply ..."

Proposed Changes

• Use a real message_dumper image instead of ko image path, so that user can try out the samples without ko.

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[gyliu513]

lgtm, thanks @whynowy

[samodell]

/lgtm
/approve

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[ahmetb]

I see you just used a message_dumper image without any tags here @whynowy.

Looks like in gcp-pubsub-source/subscriber.yaml we have this image's tag automatically provided:

docs/eventing/samples/gcp-pubsub-source/subscriber.yaml

Lines 11 to 15 in 9689f68

	spec:
	container:
	# This corresponds to
	# https://github.com/knative/eventing-sources/blob/release-0.3/cmd/message_dumper/dumper.go
	image: gcr.io/knative-releases/github.com/knative/eventing-sources/cmd/message_dumper@sha256:8423232db7a7b4010c0cfbfaef95745efe962631af9b7456903825801a7893f7

Does anyone know the cronjob sample doesn't have this comment and the sha256 tag of the same image? Is there an automation at play here? If so, both YAMLs should use the same mechanism?

/cc @FuriKuri
(last person to edit that line from "git blame")

[knative-prow-robot]

@ahmetb: GitHub didn't allow me to request PR reviews from the following users: FuriKuri.

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In response to this:

I see you just used a message_dumper image without any tags here @whynowy.

Looks like in gcp-pubsub-source/subscriber.yaml we have this image's tag automatically provided:

docs/eventing/samples/gcp-pubsub-source/subscriber.yaml

Lines 11 to 15 in 9689f68

	spec:
	container:
	# This corresponds to
	# https://github.com/knative/eventing-sources/blob/release-0.3/cmd/message_dumper/dumper.go
	image: gcr.io/knative-releases/github.com/knative/eventing-sources/cmd/message_dumper@sha256:8423232db7a7b4010c0cfbfaef95745efe962631af9b7456903825801a7893f7

Does anyone know the cronjob sample doesn't have this comment and the sha256 tag of the same image? Is there an automation at play here? If so, both YAMLs should use the same mechanism?

/cc @FuriKuri
(last person to edit that line from "git blame")

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[whynowy]

@ahmetb Not sure if they explicitly added the sha256 tag or did it with an automation. Currently CronJob is doing the way as github (https://github.com/knative/docs/blob/master/eventing/samples/github-source/service.yaml#L12), uses the lastest tag.

[ahmetb]

I opened #830 which explains the situation better.