Better readme to Helm chart

[kbegiedza]

Motivation and context

Trying to install and configure with helm was very painful, this PR tries to cover few things:

• Better readme for first time users
• Init container with automatically invoked db migration

How has this been tested?

Dry-run helm and released to brand new cluster.
Checked https certificates and frontend / backend connection.

Checklist

• I submit my changes into the develop branch
• I have added a description of my changes into CHANGELOG file
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (read github docs)
• I have increased versions of npm packages if it is necessary (cvat-canvas,
  cvat-core, cvat-data and cvat-ui)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below)

# Copyright (C) 2022 Intel Corporation
#
# SPDX-License-Identifier: MIT

[nmanovic]

@kbegiedza , thanks for your contribution! @azhavoro , could you please look?

[azhavoro]

@kbegiedza Hello, what issue does the init container you added in this patch solve?

[kbegiedza]

@azhavoro Thanks for question.
It simplifies helm deployment by removing manual process (migration on first deployment).

Without it, I had to manually exec manage.py migrate inside pod, because database was empty.

[azhavoro]

@azhavoro Thanks for question. It simplifies helm deployment by removing manual process (migration on first deployment).

Without it, I had to manually exec manage.py migrate inside pod, because database was empty.

The back-end container startup process invokes the migration on every run, including the first https://github.com/openvinotoolkit/cvat/blob/develop/supervisord.conf#L62 and I don't see the command is overridden in the deployment https://github.com/openvinotoolkit/cvat/blob/develop/helm-chart/templates/cvat_backend/deployment.yml#L44-L117 and it seems that this init container looks unnecessary. Your changes to README.md look ok, but I think it's better to understand why the migration is not run on first deployment in your case.

[kbegiedza]

Thanks for review @azhavoro, will remove init container from PR and investigate it further (and open new one if needed).

[kbegiedza]

@azhavoro fix'd

[azhavoro]

Sorry for the late response, LGTM

[nmanovic]

@kbegiedza , thanks for your contribution!