[cli] Simpler networking config explanation & command line overrides

[TylerJewell]

What does this PR do?

Adding improvements on configuring Che for common scenarios. We have seen that users who provide CHE_HOST or CHE_PORT on the command line want that to override the values of che.env. Today, it is the reverse where values in the environment file would override the command line.

This set of changes applies an algorithm that will take any values of CHE_* or {CHE_PRODUCT_NAME}_* that are passed on the command line and insert those parameters into the config method, generating an instance-specific .env file which will be used by the Che server when it is started. If this is ARTIK or CODENVY, it will load both the CHE_* and ARTIK_* and CODENVY_* variables, so that anything that we provide as a parameter in a *.env file can now be overridden on the command line.

Matching PRs:

1. Codenvy: WIP - [cli] Clearer networking configuration & CLI override for CODENVY_HOST codenvy/codenvy#1764
2. ARTIK: https://github.com/codenvy/artik/pull/337
3. Codenvy SAAS: https://github.com/codenvy/saas/pull/143

Changelog

Make command-line CHE_HOST or CHE_PORT override che.env values.

Release Notes

Docker command-line environment variables CHE_HOST or CHE_PORT override che.env values.

Docs PR

eclipse-che/che-docs#137

[codenvy-ci]

Build success. https://ci.codenvycorp.com/job/che-pullrequests-build/1943/

[TylerJewell]

@eivantsov - you may want to run a quick test. I did a series of tests to demonstrate that CHE_HOST and CHE_PORT provided on the command line will now override any setting provided in the environment file.

[codenvy-ci]

Build # 1945 - FAILED

Please check console output at https://ci.codenvycorp.com/job/che-pullrequests-build/1945/ to view the results.

[codenvy-ci]

Build success. https://ci.codenvycorp.com/job/che-pullrequests-build/1948/

[riuvshin]

this PR does not work for me on Mac

I've build base cli and init images from branch started che, then I tried
docker run ... restart --skip:nightly --skip:pull -e CHE_PORT=9090 and nothing changed

[TylerJewell]

@riuvshin syntax had a mistake - the -e CHE_PORT= needs to appear before the image name, not after it. Once we moved it, then Che started with the custom property.

[riuvshin]

tested on mac and ubuntu - works

[riuvshin]

tesed on digital ocean, it works but we have issue with generation secure random which takes up to 10 minutes on instances with low entroy.

2017-02-14 12:10:01,402[ost-startStop-1]  [INFO ] [o.a.c.u.SessionIdGeneratorBase 241]  - Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [515,672] milliseconds.

[riuvshin]

I've added -Djava.security.egd=file:/dev/./urandom to CHE JAVA_OPTS to avoid this

[codenvy-ci]

Build success. https://ci.codenvycorp.com/job/che-pullrequests-build/1971/