creating snapshots of CK repositories for Artifact Evaluation

[Grigori Fursin]

Hi all,

Several CK users recently asked me about how to make a self-contained
and stable snapshot of a given CK repository with all sub-dependencies
for Artifact Evaluation.

We recently automated this process and you can now create a snapshot of
a given repository with all dependencies (sub-repos) together with the
latest CK framework in one zip file simply as follows:

```
$ ck snapshot artifact --repo={alias of a repository for a snapshot}
```

For example, you can snapshot ck-tensorflow repository as follows:

```
$ ck pull repo:ck-tensorflow
$ ck snapshot artifact --repo=ck-tensorflow
```

CK will create a ck-artifacts-{date].zip which will also include the
following scripts for Linux/MacOS and Windows:

* prepare_virtual_ck.sh and prepare_virtual_ck.bat
* run_virtual_ck.sh and run_virtual_ck.bat

The first one will install all CK repositories from the snapshot inside
your current directory. It will also set your environment variables as
such that they will not influence you current CK installation (some sort
of virtual CK) while you can prepare and run all snapshot workflows.

You can then run the second script to set up such “virtual” environment
and open a bash on Linux/MacOS or cmd on Windows. You can then use CK
commands to prepare and run shared workflows from a given repository.

You can find such snapshots in the ACM Digital Library for the artifacts
from the ReQuEST tournament: https://dl.acm.org/citation.cfm?doid=3229762

Have a good weekend,
Grigori