bash 3.x compatibility; avoid mapfile

[pda]

Use of mapfile was introduced in da2472f (to fix a shellcheck) and 509678c (to support awscli v2). mapfile was introduced in bash 4.x, but there are many systems that ship with bash 3.x (perhaps just macOS, but there's a lot of macOS systems 😅).

This patch takes advice from shellcheck at https://github.com/koalaman/shellcheck/wiki/SC2207 to use bash 3.x compatible read -a to remove the dependency on mapfile while also avoiding the previous shellcheck warnings.

Fixes #46, closes #47.

Ping: @pdbreen @ryansdwilson @kkolk

[jayco]

This looks good! Would be awesome to get @toolmantim 👀 on this also.

[toolmantim]

@pda bash is always beyond my bash!

I think we might have to remove the integration test for now, on our new untrusted VM world

[pda]

Removing that acceptance test in #49

[brett-anderson]

Thanks for jumping on this fix Paul, I tried running this this morning with your patch and got:

 line 134: account_ids[*]: unbound variable

this is what my pipeline config looks like:

- ecr#5b8f36f57f756f65b1b4fbe265e99e91844996d0:
          login: true
          no-include-email: true

Any idea why account_ids is unbound?

Edit:

I added my account ID and it ran successfully.

[pdbreen]

Thanks @pda - and very timely. Turned out much of my day was working on pipelines and this helped speed up the change/test cycle time by an amazing amount by testing local. Other than needing to set account_ids like Brett mentioned, worked great.

[pda]

Interesting… it appears bash 3.x treats ${array[*]} as unbound if the array exists but is empty, while newer bash works as expected.

for ver in 3.2 4.4 5.0; do
    docker run --rm bash:$ver bash -u -c 'echo $BASH_VERSION; a=(); echo ${a[*]} ok';
done

# 3.2.57(1)-release
# bash: a[*]: unbound variable

# 4.4.23(1)-release
# ok

# 5.0.17(1)-release
# ok

I've pushed a change to check for emptiness in a different way:

-  if [[ -z ${account_ids[*]} ]]; then
+  if [[ ${#account_ids[@]} -eq 0 ]]; then

The semantics are slightly different if the array contains a single empty string:

set -u
a=("")
echo "count: ${#a[@]}"
if [[ -z "${a[*]}" ]]; then echo "empty"; else echo "non-empty"; fi

# count: 1
# empty

But I don't think that's a problem for us 🤞🏼

[pda]

Actually I ended up using a combination of the two approaches, to keep the old behaviour but avoid the bash 3.x error:

-  if [[ -z ${account_ids[*]} ]]; then                                  # before this PR
-  if [[ ${#account_ids[@]} -eq 0 ]]; then                              # earlier in this PR
+  if [[ ${#account_ids[@]} -eq 0 || -z "${account_ids[*]}" ]]; then    # combo

It only reaches the -z "${account_ids[*]}" part if the array is not empty, so that avoids the bash 3.x weirdness.

[pda]

(also, rebased onto #49 to get rid of the already-failing acceptance test; should give us a ✅ on this PR)