fix(image): install psmisc and net-tools to provide fuser and netstat

[fffonion]

fuser as added as a depenndecy in 3.0.0.0 to test opentelemetry plugin,
but as that's a CE plugin, it wasn't using pongo to test before. In 3.2.x.x, a
new EE plugin starts to use the same helper function that calls fuser
(and also netstat) and result in a command not found in pongo test.

[Tieske]

This cannot be right. The Pongo image is created from an official Kong image. So if those tools are not in the Pongo image, then they are also not in the official image. So I guess the official image needs to be fixed here?

[fffonion]

@Tieske yes they are not in the official image at the beginning:

docker run --user=0 -it --rm kong/kong-gateway:3.0.0.0 bash
root@0af25f0c3b3d:/# netstat
bash: netstat: command not found
root@0af25f0c3b3d:/# fuser
bash: fuser: command not found
root@0af25f0c3b3d:/#

It's not an issue before because on CI we are not running core tests in a container, and host system have those tools installed; and plus no EE plugins were using the two spec.helper functions that requires the tool utils before.

And we don't want to install a tool that's not a run-time dependency into kong official docker image, for both run-time security and vulnerability scanning reasons.

[Tieske]

ok, so I was misunderstanding it seems.

The dependencies on those tools;

• is it a runtime dependency for the plugin? (eg. the plugin won't work unless they are installed?) --> the tools should be in the base Kong image
• or is it a test dependency only used by the test helpers to test the plugin functionality? and if that is the case;
  • is it specific for this plugin, --> then the Pongo setup script for the plugin can be used to install it when the plugin tests run (no need to put in in every Pongo image)
  • is it a generic tool for testing and reusable for other tests? --> This PR is right, we add it to the Pongo generated image

So which one is it then?

[fffonion]

@Tieske It's from generic helper functions in spec.helpers.
fuser is for https://github.com/Kong/kong-pongo/blob/master/kong-versions/3.1.1.3/kong/spec/helpers.lua#L1414
and netstat for https://github.com/Kong/kong-pongo/blob/master/kong-versions/3.1.1.3/kong/spec/helpers.lua#L225.
They are reusable by other tests yes, including opentelemetry (it's OSS) plugin and some core tests.

They are not runtime dependency for either core, opentelemtry plugin or the new datadog-tracing plugin (coming in EE 3.2, which requires them in tests).

[Tieske]

ok, then the only thing missing seems to be a changelog entry

[fffonion]

changelog added!