Try to detect ssh and telnet port

[Martin-Zeithaml]

Proposed changes

Try to detect ssh and telnet port by looking into /etc/ssh/sshd_config and /etc/services. If such check fails, set the default port 22 and 23 (same as now).

This PR addresses Issue:

• Auto detect the TN3270 and the ssh ports during the install zowe-install-packaging#292
  • The PR suggested to add this check into configuration process. I believe it is better to do it during the app-server start-up. This approach is independent on the zowe.yaml changes: you can set the Zowe not to use app-server and later change it.
• FSUM7422 node is not found zlux#1022
  • There are 2 confusing messages related to node and as discussed in the issue, this node check is not needed.

Type of change

• New feature (non-breaking change which adds functionality)

PR Checklist

Please delete options that are not relevant.

• If the changes in this PR are meant for the next release / mainline, this PR targets the "staging" branch.
• My code follows the style guidelines of this project (see: Contributing guideline)
• I have commented my code, particularly in hard-to-understand areas
• Relevant update to CHANGELOG.md
• My changes generate no new warnings

Testing

Small unit test

Test for checking if the logic works as expected:

Input='' -> SSH_PORT=22
Input=' ' -> SSH_PORT=22
Input='123 ' -> SSH_PORT=22
Input='0' -> SSH_PORT=22
Input='asdf' -> SSH_PORT=22
Input='99999' -> SSH_PORT=22
Input='file not found' -> SSH_PORT=22
Input='C:\' -> SSH_PORT=22
Input='1' -> SSH_PORT=1
Input='23' -> SSH_PORT=23
Input='144' -> SSH_PORT=144
Input='65535' -> SSH_PORT=65535

Running without variables

In the log:

ZWED_SSH_PORT=22
ZWED_TN3270_PORT=23

Running with preset ZWED_SSH_PORT

In the log:

ZWED_SSH_PORT=123
ZWED_TN3270_PORT=23

Further comments

I keep the setting in defaults.yaml. It should work without that, because those variables are exported. But in the future, there might be a way how to do it in JavaScript, keep it as reference.

[1000TurquoisePogs]

Regarding the reading of these here:
Just did a lot of work in v2.15-v2.18 to remove as much shell as possible for performance.

1. start.sh gets read every time the server starts, including crash restarts. configure.sh does not get read during crash restarts so its a little better...

2. configure.sh still gets read every fresh start. can we do this in JS instead? - read the file, line split and search for term.... we already have "initInstance.js". It could be made more intelligent.

initUtils.js takes these env vars and writes out JSON in workspace dir.
If it would instead do pretty much this logic when the env vars were missing, we wouldn't need to put this code into shell and the performance impact would be much less.

[Martin-Zeithaml]

Replaced by #326.