versions: Add versions database

[jodh-intel]

Add a YAML format database that is the equivalent of the Clear
Containers versions.txt file [1].

The file defines the versions of important non-golang dependencies used
by this and other Kata repositories particularly for testing and packaging.

Defining all version details centrally in this file avoids duplication
and "bitrot" when versions need to be changed.

[1] - https://github.com/clearcontainers/runtime/blob/master/versions.txt

Fixes #11.

Signed-off-by: James O. D. Hunt james.o.hunt@intel.com

[jodh-intel]

This is a "proof-of-concept" for what a YAML version of the Clear Containers versions.txt database might look like.

Note that being YAML:

• it is structured
• we can add comments
• we can also add other details like URL's that are part of the database.
• built-in handling of structure changes.
  Since it's possible we'll need to change the structure of this file if we do decide to use YAML, it's worth pointing out that YAML has builtin support for references. What this means is that we can redefine the structure of the file, but still keep backwards compatability for "clients" accessing it using yq for example!

Example of retaining compatability

If we started off with this fragment for storing golang details...

golang:
  versions:
    minimum: "1.8.3"
    version: "1.10"

... but then decided we want to move the entire golang block (array) below languages...

# XXX: retained for backwards compat!
golang:
  versions:
    minimum: *golang-versions-minimum
    version: *golang-versions-version

languages:
  golang:
    minimum: &golang-versions-minimum "1.8.3"
    version: &golang-versions-version "1.10"

... you can query the minimum golang version using either of the following queries:

$ yq read versions.yaml languages.golang.minimum
1.8.3
$ yq read versions.yaml golang.versions.minimum
1.8.3

/cc @grahamwhaley, @sboeuf, @jcvenegas, @erick0z, @chavafg, @bergwolf.

[sboeuf]

Maybe you should double quote every version in this file ? No confusion this way

[jodh-intel]

Good call. It might be overkill, but I've gone for the nuclear option - all strings are quoted for maximum safety.

[jodh-intel]

Branch updated. The contents of this file is basically verbatim what we had in CC. Although we might need to adjust (or even remove) some values subsequently, there is no harm in merging this.

[jodh-intel]

Ping @kata-containers/runtime.

[jcvenegas]

@jodh-intel this looks great, I wonder if we could generalize the format for all the dependencies and have a template in the comments. If we have an standar format. Then we could use it for our release notes.

<group>:
   description:<>
   <project>:
       url:<URL>
       commit:<commit>
       version:<>
       description:"<>"
       meta:
         <key>: "<val>"

[jodh-intel]

@jcvenegas - I like it! Branch updated!

[jodh-intel]

@sboeuf, @devimc, @erick0z - should this be named qemu-lite dyt? Or would it be better to add something like:

meta:
  variant: "qemu-lite"

[jodh-intel]

Related: kata-containers/tests#163.

[grahamwhaley]

nice progression of our formalisation and automation...
lgtm

[grahamwhaley]

I guess the vim line does no harm ;-) (and I am a vim user... )

[jodh-intel]

ick - I'd forgotten that was there - removing!

[jodh-intel]

Another thought... considering the golang versions and also docker versions (see #92), I wonder if we want to generalise this further and specify two versions for every entry. For example:

golang:
  min-version: "1.8.3"
  max-version: "1.10"

docker:
  min-version: "..."
  max-version: "..."

Iff we do that, we'll have to maintain both those versions though. And that would imply we'd need to test with both versions regularly. It also suggests we could abstract "version" into something like a Revision object:

# Representation of some form of software versions.
# Atleast one of the value must be specified.
!Revision {
  version: "..."
  release: "..."
  commit: "..."
}

We could then define entries like this:

docker:
  min-version: !Revision{version: "1.8.3"}

kernel:
  min-revision: !Revision {version: "v4.14.22-86.container",  release: "19790"}

This might be too much complexity though since the only two entries that currently specify multiple versions are docker (for swarm) and golang (and that meta entry could be dropped).