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5 commits

Author SHA1 Message Date
W. Trevor King 31e3a50ddd hooks/README: Fix some Markdown typos (e.g. missing runc target)
I'd accidentally introduced these typos in ea415610 (hooks/docs: Add
oci-hooks.5 and per-package man page building, 2018-05-15, #772).

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #810
Approved by: mheon
2018-05-21 14:09:25 +00:00
W. Trevor King ea4156108d hooks/docs: Add oci-hooks.5 and per-package man page building
This allows us to reference the hooks docs from podman(1) in a way
that will survive system installation.  The downside is that the
GitHub rendered pages become less usable, now that we can no longer
embed links as freely as we could before.

I've followed the "Sections within a manual page" suggestions from
[1].

locale(7) is [2], which is Linux-specific.  Even section numbering is
platform-dependent [3], so it's unlikely that these external man
references are particularly portable.  Platform packagers can adjust
our local references to match their target system, but that leaves the
GitHub rendering in an awkward place.  For now, I think a
Linux-centric GitHub rendering without clickable links may be the best
we can do without moving away from go-md2man.

As far as I can tell, there's not a nice way to get go-md2man to wrap
the links in SEE ALSO without sometimes hyphenating a URL (which makes
it harder for man-page readers to copy/paste those links into their
browser).

I've also fixed some "extention" -> "extension" typos.

[1]: http://man7.org/linux/man-pages/man7/man-pages.7.html
[2]: http://man7.org/linux/man-pages/man7/locale.7.html
[3]: https://en.wikipedia.org/wiki/Man_page#Manual_sections

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #772
Approved by: mheon
2018-05-17 18:22:10 +00:00
W. Trevor King 45838b9561 hooks: Add package support for extension stages
We aren't consuming this yet, but these pkg/hooks changes lay the
groundwork for future libpod changes to support post-exit hooks [1,2].

[1]: https://github.com/projectatomic/libpod/issues/730
[2]: https://github.com/opencontainers/runc/issues/1797

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #758
Approved by: rhatdan
2018-05-14 21:36:48 +00:00
W. Trevor King 89430ffe65 hooks: Order injection by collated JSON filename
We also considered ordering with sort.Strings, but Matthew rejected
that because it uses a byte-by-byte UTF-8 comparison [1] which would
fail many language-specific conventions [2].

There's some more discussion of the localeToLanguage mapping in [3].
Currently language.Parse does not handle either 'C' or 'POSIX',
returning:

  und, language: tag is not well-formed

for both.

[1]: https://github.com/projectatomic/libpod/pull/686#issuecomment-387914358
[2]: https://en.wikipedia.org/wiki/Alphabetical_order#Language-specific_conventions
[3]: https://github.com/golang/go/issues/25340

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #686
Approved by: mheon
2018-05-11 16:26:35 +00:00
W. Trevor King 68eb128fb0 pkg/hooks: Version the hook structure and add 1.0.0 hooks
This shifts the matching logic out of libpod/container_internal and
into the hook package, where we can reuse it after vendoring into
CRI-O.  It also adds unit tests with almost-complete coverage.  Now
libpod is even more isolated from the hook internals, which makes it
fairly straightforward to bump the hook config file to 1.0.0.  I've
dubbed the old format 0.1.0, although it doesn't specify an explicit
version.  Motivation for some of my changes with 1.0.0:

* Add an explicit version field.  This will make any future JSON
  structure migrations more straightforward by avoiding the need for
  version-guessing heuristics.

* Collect the matching properties in a new When sub-structure.  This
  makes the root Hook structure easier to understand, because you
  don't have to read over all the matching properties when wrapping
  your head around Hook.

* Replace the old 'hook' and 'arguments' with a direct embedding of
  the runtime-spec's hook structure.  This provides access to
  additional upstream properties (args[0], env, and timeout) and
  avoids the complication of a CRI-O-specific analog structure.

* Add a 'when.always' property.  You can usually accomplish this
  effect in another way (e.g. when.commands = [".*"]), but having a
  boolean explicitly for this use-case makes for easier reading and
  writing.

* Replace the previous annotations array with an annotations map.  The
  0.1.0 approach matched only the values regardless of key, and that
  seems unreliable.

* Replace 'cmds' with 'when.commands', because while there are a few
  ways to abbreviate "commands", there's only one way to write it out
  in full ;).  This gives folks one less thing to remember when
  writing hook JSON.

* Replace the old "inject if any specified condition matches" with
  "inject if all specified conditions match".  This allows for more
  precise targeting.  Users that need more generous targeting can
  recover the previous behavior by creating a separate 1.0.0 hook file
  for each specified 0.1.0 condition.

I've added doc-compat support for the various pluralizations of the
0.1.0 properties.  Previously, the docs and code were not in
agreement.  More on this particular facet in [1].

I've updated the docs to point out that the annotations being matched
are the OCI config annotations.  This differs from CRI-O, where the
annotations used are the Kubernetes-supplied annotations [2,3].  For
example, io.kubernetes.cri-o.Volumes [4] is part of CRI-O's runtime
config annotations [5], but not part of the Kubernetes-supplied
annotations CRI-O uses for matching hooks.

The Monitor method supports the CRI-O use-case [6].  podman doesn't
need it directly, but CRI-O will need it when we vendor this package
there.

I've used nvidia-container-runtime-hook for the annotation examples
because Dan mentioned the Nvidia folks as the motivation behind
annotation matching.  The environment variables are documented in [7].
The 0.1.0 hook config, which does not allow for environment variables,
only works because runc currently leaks the host environment into the
hooks [8].  I haven't been able to find documentation for their usual
annotation trigger or hook-install path, so I'm just guessing there.

[1]: https://github.com/kubernetes-incubator/cri-o/pull/1235
[2]: https://github.com/kubernetes-incubator/cri-o/blob/v1.10.0/server/container_create.go#L760
[3]: https://github.com/kubernetes-incubator/cri-o/blob/v1.10.0/server/container_create.go#L772
[4]: https://github.com/kubernetes-incubator/cri-o/blob/v1.10.0/pkg/annotations/annotations.go#L97-L98
[5]: https://github.com/kubernetes-incubator/cri-o/blob/v1.10.0/server/container_create.go#L830-L834
[6]: https://github.com/kubernetes-incubator/cri-o/pull/1345/
[7]: https://github.com/NVIDIA/nvidia-container-runtime/tree/v1.3.0-1#environment-variables-oci-spec
[8]: https://github.com/opencontainers/runc/pull/1738

Signed-off-by: W. Trevor King <wking@tremily.us>

Closes: #686
Approved by: mheon
2018-05-11 16:26:35 +00:00