The kernel ABI to these values is a string, which accepts the value `-1`
to mean "unlimited" or an integer up to 2^63 for an amount of memory in
bytes.
While the internal representation in the kernel is unsigned, this is not
exposed in any ABI directly. Because of the user-kernel memory split, values
over 2^63 are not really useful; indeed that much memory is not supported,
as physical memory is limited to 52 bits in the forthcoming switch to five
level page tables. So it is much more natural to support the value `-1` for
unlimited, especially as the actual number needed to represent the maximum
has varied in different kernel versions, and across 32 and 64 bit architectures,
so determining the value to use is not possible, so it is necessary to write
the string `-1` to the cgroup files.
See also discussion in
- https://github.com/opencontainers/runc/pull/1494
- https://github.com/opencontainers/runc/pull/1492
- https://github.com/opencontainers/runc/pull/1375
- https://github.com/opencontainers/runc/issues/1421
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
These are long enough without the prefix, and
linux.resources.blockIO.blkioWeight, etc. are just as specific as
linux.resources.blockIO.weight.
Generated with:
$ sed -i s/blkioWeight/weight/g $(git grep -l blkioWeight)
$ sed -i s/blkioLeaf/leaf/g $(git grep -l blkioLeaf)
$ sed -i s/blkioThrottle/throttle/g $(git grep -l blkioThrottle)
Signed-off-by: W. Trevor King <wking@tremily.us>
We have an explicit policy for example header levels in style.md, so
follow that in config-linux.md. Also adjust the non-example headers
to be one level deeper than their parent.
Signed-off-by: W. Trevor King <wking@tremily.us>
727e64d9 (config-linux.md: fix wrong link description about cgroups,
2017-05-14, #826) added a redundant link name for libseccomp. This
commit restores the old implicit link name shortcut [1] there and
updates the other entries (all of which were for the filesystems table
in config-linux) that could also use that shortcut. This is obviously
not a major change, but I think it makes the source easier to read by
minimizing the markup so you can focus on the text.
[1]: https://daringfireball.net/projects/markdown/syntax#link
Signed-off-by: W. Trevor King <wking@tremily.us>
Catch the Markdown spec up with the JSON Schema change in 09274372
(schema: Drop pointers and nulls, 2017-01-18, #662). The Markdown is
canonical, so we could restore the explicit-null handling to the JSON
Schema instead, but the maintainers feel (and I agree) that there's no
point in explicitly allowing a null value when callers can simply
leave the property unset [1].
[1]: https://github.com/opencontainers/runtime-spec/pull/555#issuecomment-272020515
Signed-off-by: W. Trevor King <wking@tremily.us>
Any runtime which violated that constraint would necessarily violate
some more specific constraint on a 'resources' setting.
This also removes a non-spec-requirement "required" to avoid any
confusion with the spec-requirement REQUIRED [1].
[1]: https://github.com/opencontainers/runtime-spec/pull/729#issue-214550260
Signed-off-by: W. Trevor King <wking@tremily.us>
Since f9dc90b0 (make link usage consistent across the specification,
2017-02-09, #687), the official style is to only use reference-style
links for external links. I expect the remaining three entries just
slipped through. This commit adjusts everything found with:
$ git grep ']: [a-z]' | grep -v http
It also fixes the underscore -> hyphen in the
glossary.md#container-namespace target and updates the capabilities
location to catch up with 5a8a779f (Move process specific settings to
process, 2016-03-02, #329).
Signed-off-by: W. Trevor King <wking@tremily.us>
The only discussion related to this is in [1,2], where the
relationship between oomScoreAdj and disableOOMKiller is raised. But
since 429f936 (Adding cgroups path to the Spec, 2015-09-02, #137)
resources has been tied to cgroups, and oomScoreAdj is not about
cgroups. For example, we currently have (in config-linux.md):
You can configure a container's cgroups via the resources field of
the Linux configuration.
I suggested we move the property from linux.resources.oomScoreAdj to
linux.oomScoreAdj so config authors and runtimes don't have to worry
about what cgroupsPath means if the only entry in resources is
oomScoreAdj. Michael responded with [4]:
If anything it should probably go on the process
So that's what this commit does.
I've gone with the four-space indents here to keep Pandoc happy (see
7795661 (runtime.md: Fix sub-bullet indentation, 2016-06-08, #495),
but have left the existing entries in this list unchanged to reduce
churn.
[1]: https://github.com/opencontainers/runtime-spec/pull/236
[2]: https://github.com/opencontainers/runtime-spec/pull/292
[3]: https://github.com/opencontainers/runtime-spec/pull/137
[4]: https://github.com/opencontainers/runtime-spec/issues/782#issuecomment-299990075
Signed-off-by: W. Trevor King <wking@tremily.us>
So we can compliance-test runtimes for these settings.
Also remove the tutorial, since the kernel docs should provide
sufficient documentation on that front. The kernel can be patched if
they do not, and we do not include tutorials for other config-linux
settings in this spec.
The updated example was recommended by Xiaochen to compensate for the
removed inline tutorial [1].
[1]: https://github.com/opencontainers/runtime-spec/pull/787#discussion_r114254422
Signed-off-by: W. Trevor King <wking@tremily.us>
The previous wording hinted at, but did not require, this setting to
be implemented via oom_score_adj. With the new wording, when proc is
mounted at /proc, the container process can check this value by
looking at /proc/self/oom_score_adj.
Signed-off-by: W. Trevor King <wking@tremily.us>
Before this commit, linux.seccomp.sycalls was required, but we didn't
require an entry in the array. That means '"syscalls": []' would be
technically valid, and I'm pretty sure that's not what we want.
If it makes sense to have a seccomp property that does not need
syscalls entries, then syscalls should be optional (which is what this
commit is doing).
If it does not makes sense to have an empty/unset syscalls then it
should be required and have a minimum length of one.
Before 652323c (improve seccomp format to be more expressive,
2017-01-13, #657), syscalls was omitempty (and therefore more
optional-feeling, although there was no real Markdown spec for seccomp
before 3ca5c6c, config-linux.md: fix seccomp, 2017-03-02, #706, so
it's hard to know). This commit has gone with OPTIONAL, because a
seccomp config which only sets defaultAction seems potentially valid.
The SCMP_ACT_KILL example is prompted by:
On Tue, Apr 25, 2017 at 01:32:26PM -0700, David Lyle wrote [1]:
> Technically, OPTIONAL is the right value, but unless you specify the
> default action for seccomp to be SCMP_ACT_ALLOW the result will be
> an error at run time.
>
> I would suggest an additional clarification to this fact in
> config-linux.md would be very helpful if marking syscall as
> OPTIONAL.
I've phrased the example more conservatively, because I'm not sure
that SCMP_ACT_ALLOW is the only possible value to avoid an error. For
example, perhaps a SCMP_ACT_TRACE default with an empty syscalls array
would not die on the first syscall. The point of the example is to
remind config authors that without a useful syscalls array, the
default value is very important ;).
Also add the previously-missing 'required' property to the seccomp
JSON Schema entry.
[1]: https://github.com/opencontainers/runtime-spec/pull/768#issuecomment-297156102
Signed-off-by: W. Trevor King <wking@tremily.us>
This was broken by f9dc90b0 (make link usage consistent across the
specification, 2017-02-09, #687), which updated the link label, but
not this link. Now that the link label matches the link text, we can
use the implicit link name shortcut [1].
[1]: https://daringfireball.net/projects/markdown/syntax#link
Signed-off-by: W. Trevor King <wking@tremily.us>
I expect the (undocumented) intention here is to iterate through
'names' and call seccomp_rule_add(3) or similar for each name. In
that case, an empty 'names' makes the whole syscall entry a no-op, and
with this commit we can warn users who are validating such configs.
If, on the other hand, we were comfortable with no-op syscall entries,
we'd want to make 'names' OPTIONAL.
Warning folks who accidentally empty (or don't set) 'names' seems more
useful to me, and doesn't restrict the useful config space, so that's
what I've gone with in this commit.
minItems is documented in [1], and there is an example of its use in
[2]:
"options": {
"type": "array",
"minItems": 1,
"items": { "type": "string" },
"uniqueItems": true
},
[1]: https://tools.ietf.org/html/draft-wright-json-schema-validation-00#section-5.11
[2]: http://json-schema.org/example2.html
Signed-off-by: W. Trevor King <wking@tremily.us>
We have a few different element types in our arrays, so it's useful to
clarify the element type for the property being specified. Before
this commit:
$ sed -n 's|.*\*\*`\([^`]*\)`\*\*[^(]*(\([^,]*\),.*|\2|p' *.md | sort | uniq -c | grep array
7 array
1 array of ints
8 array of objects
13 array of strings
All of the bare 'array' instances turned out to be arrays of objects.
Signed-off-by: W. Trevor King <wking@tremily.us>
Justin Cormack