'destination' has been the path inside the container since c18c283a
(Change layout of mountpoints and mounts, 2015-09-02, #136). My
personal preference is to have an explicit pivot root and allow paths
relative to the current working directory [1], but that would be a big
shift from the current OCI spec. The only way the current spec lets
you turn off the root pivot is by not setting a mount namespace at all
(and even then, it's not clear if that turns off the pivot). And the
config's root entry is required (despite my attempts to have it made
optional [2]), so it's not really clear how containers that don't set
a mount namespace are supposed to work (if they're supported at all).
You might be able to get away with something like:
When a mount namespace is not set, destination paths are relative to
the runtime's initial working directory (or relative to the
config.json, or whatever). When a mount namespace is set,
destination paths are relative to the mount namespace's root.
but with mount-namespace-less containers already so unclear, it seems
better to just require absolute destinations. If/when we get clearer
support for explicit pivot-root calls or containers that inherit the
host mount namespace (without re-joining it and losing their old
working directory), we can consider lifting the absolute-path
restriction.
[1]: https://github.com/wking/ccon/tree/v0.4.0#mount-namespace
[2]: https://groups.google.com/a/opencontainers.org/forum/#!topic/dev/6ZKMNWujDhU
Date: Wed, 26 Aug 2015 12:54:47 -0700
Subject: Dropping the rootfs requirement and restoring arbitrary bundle
content
Message-ID: <20150826195447.GX21585@odin.tremily.us>
Signed-off-by: W. Trevor King <wking@tremily.us>
Pin down our JSON definition to a particular RFC (which we can
explicitly bump if neccessary), instead of referencing the floating
JSON homepage.
Explicitly make objects unordered and forbid duplicate names to avoid
relying on unportable behavior. RFC 7159 is a bit more relaxed [1]:
The names within an object SHOULD be unique.
but warns [1]:
An object whose names are all unique is interoperable in the sense
that all software implementations receiving that object will agree
on the name-value mappings. When the names within an object are not
unique, the behavior of software that receives such an object is
unpredictable. Many implementations report the last name/value pair
only. Other implementations report an error or fail to parse the
object, and some implementations report all of the name/value pairs,
including duplicates.
The RFC also warns about order portability [1]:
JSON parsing libraries have been observed to differ as to whether or
not they make the ordering of object members visible to calling
software. Implementations whose behavior does not depend on member
ordering will be interoperable in the sense that they will not be
affected by these differences.
And has some (informative?) language about entries being unordered
[2]:
An object is an unordered collection of zero or more name/value
pairs...
[1]: https://tools.ietf.org/html/rfc7159#section-4
[2]: https://tools.ietf.org/html/rfc7159#section-1
Signed-off-by: W. Trevor King <wking@tremily.us>
In all of these cases we want to use the RFC 2119 semantics.
Generated with:
$ sed -i 's/required/REQUIRED/g' config*.md
after which I rolled back the change for:
...controllers required to fulfill...
since that was already MUSTed.
Signed-off-by: W. Trevor King <wking@tremily.us>
Michael Crosby
Rob Dolin (MSFT)
Daniel, Dao Quang Minh
Qiang Huang
Mike Frysinger
W. Trevor King
Zhang Wei
Mrunal Patel
Ma Shimiao
Lei Jitang
Vincent Batts
Mrunal Patel
John Howard