[3.4] Install shellcheck if it is not present

[thedtripp]

Backporting shellcheck installation method to 3.4 as described here: #18216 (review)

This is based on commit 4f23883 and pull request #14872.

Related issue: #17472

Fixed outstanding shellcheck errors [SC2086] by adding double quotes to variables where needed.

[k8s-ci-robot]

Hi @thedtripp. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

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-sigs/prow repository.

[thedtripp]

@jmhbnz @ivanvc, It looks like the CI for 3.4 isn't testing on ARM. Does this mean I should omit the code that will install the ARM version of shellcheck if needed?

if [ "$GOARCH" == "amd64" ]; then
    URL="https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION}/shellcheck-${SHELLCHECK_VERSION}.linux.x86_64.tar.xz"
elif [[ "$GOARCH" == "arm" || "$GOARCH" == "arm64" ]]; then
    URL="https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION}/shellcheck-${SHELLCHECK_VERSION}.linux.aarch64.tar.xz"

[jmhbnz]

/retitle [3.4] Install shellcheck if it is not present

[jmhbnz]

@jmhbnz @ivanvc, It looks like the CI for 3.4 isn't testing on ARM. Does this mean I should omit the code that will install the ARM version of shellcheck if needed?

if [ "$GOARCH" == "amd64" ]; then
    URL="https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION}/shellcheck-${SHELLCHECK_VERSION}.linux.x86_64.tar.xz"
elif [[ "$GOARCH" == "arm" || "$GOARCH" == "arm64" ]]; then
    URL="https://github.com/koalaman/shellcheck/releases/download/${SHELLCHECK_VERSION}/shellcheck-${SHELLCHECK_VERSION}.linux.aarch64.tar.xz"

arm64 was only added as tier1 support for release-3.5 onwards. I would leave the code in so the commit backport is the same across both branches. If that code path is not used it's not a big deal I don't think.

[ivanvc]

Hi @thedtripp, thanks for the pull request! By looking at the changes, it seems like you're doing two things in a single commit:

1. The backport
2. Addressing shellcheck violations, by adding quotes to the environment variables.

I suggest splitting your commit into two commits.

/ok-to-test

[thedtripp]

Hi @thedtripp, thanks for the pull request! By looking at the changes, it seems like you're doing two things in a single commit:

1. The backport

2. Addressing shellcheck violations, by adding quotes to the environment variables.

I suggest splitting your commit into two commits.

/ok-to-test

Ok! I'll split it up.

[jmhbnz]

LGTM - Thanks @thedtripp

[ivanvc]

LGTM. Thanks, @thedtripp :)