crictl inspecti does not print valid JSON when multiple image IDs provided

[honnix]

What happened:

I ran crictl inspecti -o json <id1> <id2>, and this output two JSON chunks instead of valid JSON array. The result makes using other tools to process output very hard.

What you expected to happen:

A valid JSON array containing two dictionaries.

How to reproduce it (as minimally and precisely as possible):

Run crictl inspecti -o json <id1> <id2> and examine the output.

Anything else we need to know?:

I guess the reason is that printing is done per image https://github.com/kubernetes-sigs/cri-tools/blob/master/cmd/crictl/image.go#L267, instead of composing a full JSON.

The same goes to YAML output as well.

So I think we can either output a complete JSON or have an option to output a single line json without pretty print. As for YAML, the only optional I think is to output multiple YAML doc separated by ---

Environment:

• Container runtime or hardware configuration: Intel(R) Xeon(R) CPU @ 2.30GHz GenuineIntel
• OS (e.g: cat /etc/os-release): GKE containerd image
• Kernel (e.g. uname -a): Linux 4.19.112+ Add e2e test framework and basic test cases. #1 SMP Fri Sep 4 12:00:04 PDT 2020 x86_64 Intel(R) Xeon(R) CPU @ 2.30GHz GenuineIntel GNU/Linux
• Others:

[honnix]

A possible workaround could be replacing the output using regex \}\s*\{ with },{ and then padding []. Still feels flaky though.

[saschagrunert]

Yeah, the same issue exists for inspecti and inspectp. The for loops are not taking the output type into account.

[fejta-bot]

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[fejta-bot]

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Mark the issue as fresh with /remove-lifecycle rotten.
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/lifecycle rotten

[honnix]

I feel this will hardly be prioritized. /close

[xiongtx]

I'm running into this issue as well. When querying 100's of images on a host it's more efficient to do one shell command than 100's. Hopefully we can get an option to turn pretty-print off.

[saschagrunert]

Approaching a fix in #1493