Pushing applications with cflinuxfs4

[acrmp]

The tile generator is currently hard-coded to push applications specifying the cflinuxfs3 stack if it is available.

tile-generator/tile_generator/templates/jobs/deploy-all.sh.erb

Lines 220 to 227 in 8cbcfb2

	function get_stack() {
	if $CF stacks 2>&1 | grep "cflinuxfs3" > /dev/null; then
	echo >&2 "Using cflinuxfs3 stack"
	echo "-s cflinuxfs3"
	else
	echo >&2 "Using default stack"
	fi
	}

It would be nice to be able to use cflinuxfs4 when it is available.

Prefer cflinuxfs4

One option would be to do something similar to what currently exists and use cflinuxfs4 if it is available, falling back to
cflinuxfs3. For example:

function get_stack() {
	latest_stack="$($CF stacks | grep 'cflinuxfs' | sort -Vr | head -n1 | awk '{print $1}')"
	if [ -z "$latest_stack" ]; then
		echo >&2 "Using default stack"
	else
		echo >&2 "Using $latest_stack stack"
		echo "-s $latest_stack"
	fi
}

This has some potential to break tiles that don't work on cflinuxfs4, though that could be a good thing if it encourages adoption of cflinuxfs4.

It might also not work if operators were on a version of TAS 3.0 that has cflinuxfs4 but does not have a buildpack with support for cflinuxfs4 that is used when pushing the app.
https://docs.vmware.com/en/VMware-Tanzu-Application-Service/3.0/tas-for-vms/runtime-rn.html#jammy-jellyfish-stack-support-beta-17

Default stack

Another option is to use the configured default stack. This means that the operator would control the stack used, though teams that are shipping tiles may prefer to have their applications use the latest stack that is available.

With the release of TAS 4.0 operators can choose to set cflinuxfs4 as the default stack:
https://docs.vmware.com/en/VMware-Tanzu-Application-Service/4.0/tas-for-vms/runtime-rn.html

Specified by tile developers

Another option would be to allow tile developers to specify the stack that should be used at build time.

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. Unfortunately, the Pivotal Tracker project is private so you may be unable to view the contents of the story.

The labels on this github issue will be updated when the story is started.

[peterhaochen47]

+1 on this (on behalf of credhub service broker tile).
Meanwhile, we'll override it just like https://github.com/vmware-tanzu/nozzle-for-microsoft-azure-log-analytics/pull/26/files