new(docker): allow passing options to falco-driver-loader from the cointainer image

[LucaGuerra]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind feature
/area build

What this PR does / why we need it:

Sometimes we may want to specify options for the driver loader script, for example when we may decide to only download or compile the eBPF probe rather than the kmod. This is not strictly required, more like something that is nice to have.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

new(docker): allow passing options to falco-driver-loader from the driver loader cointainer

[Andreagit97]

/approve

I would document it somewhere!

[poiana]

LGTM label has been added.

Git tree hash: 3938e247ce188b768023e9c7d070fca35fb83e39

[leogr]

Suggested change

	/usr/bin/falco-driver-loader "${falco_driver_loader_option_arr[@]}"
	/usr/bin/falco-driver-loader ${falco_driver_loader_option_arr[@]}

why do we need " here? 🤔
what will happen if $FALCO_DRIVER_LOADER_OPTIONS contains "? 🤔

/hold

[LucaGuerra]

It's not a good PR review if nobody mentions either mystifying Bash rules or the C standard.

The " is there to prevent variable globbing and expansion, meaning that if you pass a * in the array it will not expand to all files in this directory. Then I tried and I noticed that there is a mistake in the line above, which should be read -a args_arr <<< $FALCO_DRIVER_LOADER_OPTIONS because otherwise ... variable expansion will happen anyways. So I'm going to fix that.

To answer the second part of the question, arguments are simply space-delimited (technically, $IFS delimited).

You can verify by copying these two scripts:

print-args.sh

#!/bin/bash

for arg
do
    printf '%s\n' "$arg"
done

args-from-env.sh

#!/bin/bash

read -a args_arr <<< $MY_ARGS

echo "--- with quotes ---"
./print-args.sh "${args_arr[@]}"

echo "--- without quotes ---"
./print-args.sh ${args_arr[@]}

echo "--- without quotes and array conversion ---"
./print-args.sh ${MY_ARGS}

and running MY_ARGS='hello bash * old not friend' ./args-from-env.sh

[leogr]

🤯

[leogr]

/hold cancel

[Andreagit97]

/approve

[poiana]

LGTM label has been added.

Git tree hash: b438a74e81397f2103ed78c7e8c9aa51cbbc8169

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, FedeDP, LucaGuerra

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• docker/OWNERS [Andreagit97,FedeDP,LucaGuerra]

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