Add global tool wrapper

[viceice]

What to do
To have better compability with other workflows we should add global wrapper for installed tools.
Those wrapper should source BASH_ENV and then call normal tool, so we have our prepared env loaded.

Sample Jenkins

• Container is started like docker run ... -d --rm renovatebot/node cat
• creating a /path/to/run.sh shell script with commands at shared dir.
• Executing commands by docker exec <container-id> sh /path/to/run.sh

The exec is calling default sh command in env, which will be linked to dash on our ubuntu image.
Overwriting it to bash won't help, as it won't source BASH_ENV.
exec is also not calling entrypoint, so again no BASH_ENV sourcing.

Solution

creating shell wrapper like we did for node < 15

docker-buildpack/src/node/buildpack/tools/node.sh

Lines 39 to 42 in 7fe5151

	if [[ ${MAJOR} < 15 ]]; then
	# backward compatibillity
	shell_wrapper node
	fi

docker-buildpack/src/base/buildpack/util.sh

Lines 56 to 76 in 97680db

	# use this if custom env is required, creates a shell wrapper to /usr/local/bin
	function shell_wrapper () {
	local FILE="/usr/local/bin/${1}"
	check_command $1
	cat > $FILE <<- EOM
	#!/bin/bash
	if [[ -f "\$BASH_ENV" && -z "${BUILDPACK+x}" ]]; then
	. \$BASH_ENV
	fi
	if [[ "\$(command -v ${1})" == "$FILE" ]]; then
	echo Could not forward ${1}, probably wrong PATH variable. >&2
	echo PATH=\$PATH
	exit 1
	fi
	${1} \${@}
	EOM
	chmod +x $FILE
	}

[viceice]

This would also allow doing docker exec <container> go --version and other commands, which currently fail because of not loading our env

[rarkins]

So for each tool x, it would actually call a wrapper of ours, which would do env export and then call the real x?

Would the wrapper locate the real x using $PATH somehow (e.g. finding the second x in the path after itself) or would it simply "know" which path for x to use because we installed it?

[viceice]

the wrapper sources our env, after it the wrapper will be later in path so it simply calls the real x then. thats how it currently works for node.

[viceice]

Missing parts:

• add shell wrapper for install-pip
• add shell wrapper for install-gem
• java
• erlang
• docker
• php
• composer

[viceice]

Duplicate of containerbase/base#21