devmapper: Move file write and rename functionality in a separate function

Currently we save device metadata and have a helper function saveMetadata()
which converts data in json format as well as saves it to file. For
converting data in json format, one needs to know what is being saved.

Break this function down in two functions. One function only has file
write capability and takes in argument about byte array of json data.
Now this function does not have to know what data is being saved. It
only knows about a stream of json data is being saved to a file.

This allows me to reuse this function to save a different type of
metadata. In this case I am planning to save NextDeviceId so that
docker can use this device Id upon next restart. Otherwise docker
starts from 0 which is suboptimal.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
devmapper: Export nextDeviceId so that json.Marshal() can operate on it

I was trying to save nextDeviceId to a file but it would not work and
json.Marshal() will do nothing. Then some search showed that I need to
make first letter of struct field capital, exporting this field and
now json.Marshal() works.

This is a preparatory patch for the next one.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
devmapper: Save and restore NextDeviceId in a file

The way thin-pool right now is designed, user space is supposed to keep
track of what device ids have already been used. If user space tries to
create a new thin/snap device and device id has already been used, thin
pool retuns -EEXIST.

Upon receiving -EEXIST, current docker implementation simply tries the
NextDeviceId++ and keeps on doing this till it finds a free device id.

This approach has two issues.

- It is little suboptimal.
- If device id already exists, current kenrel implementation spits out
  a messsage on console.

[17991.140135] device-mapper: thin: Creation of new snapshot 33 of device 3 failed.

Here kenrel is trying to tell user that device id 33 has already been used.
And this shows up for every device id docker tries till it reaches a point
where device ids are not used. So if there are thousands of container and
one is trying to create a new container after fresh docker start, expect
thousands of such warnings to flood console.

This patch saves the NextDeviceId in a file in
/var/lib/docker/devmapper/metadata/deviceset-metadata and reads it back
when docker starts. This way we don't retry lots of device ids which 
have already been used. 

There might be some device ids which are free but we will get back to them
once device numbers wrap around (24bit limit on device ids).

This patch should cut down on number of kernel warnings.

Notice that I am creating a deviceset metadata file which is a global file
for this pool. So down the line if we need to save more data we should be
able to do that.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
devmapper: Fix gofmt related build failures

My pull request failed the build due to gofmat issues. I have run gofmt
on specified files and this commit fixes it.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
devicemapper: split out devicemapper bindings

This is a first pass at splitting out devicemapper into separate, usable
bindings.

Signed-off-by: Vincent Batts <vbatts@redhat.com>
docker-remove-redundant-json-tags

In previous patch I had introduce json:"-" tags to be on safer side to make
sure certain fields are not marshalled/unmarshalled. But struct fields
starting with small letter are not exported so they will not be marshalled
anyway. So remove json:"-" tags from there.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
This patch adds ability in docker to detect out of memory conditions in containers.
Since the containers can handle the out of memory kernel kills gracefully, docker
will only provide out of memory information as an additional metadata as part of
container status.
Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Address comments.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Cleanup api server creation

Current implementation is hard to reason about because of trying to mix
unix/tcp server implementations, even though they are quite different.
This cleans that up.

Also makes it possible to create and manage a new API server easily,
e.g. for adding an introspection socket to a container.

Built in such a way as to allow a non-HTTP server to work as well, such
as libchan.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Fix comment to match the arg name

Signed-off-by: Steven Burgess <steven.a.burgess@hotmail.com>
devmapper: Take care of some review comments

Took care of some review comments from crosbymichael.

v2:
- Return "err = nil" if file deviceset-metadata file does not exist.
- Use json.Decoder() interface for loading deviceset metadata.

v3:
- Reverted back to json marshal interface in loadDeviceSetMetaData().

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
registry: default --insecure-registry to localhost and 127.0.0.1

Signed-off-by: Johan Euphrosine <proppy@google.com>
registry: always treat 127.0.0.1 as insecure for all cases anytime anywhere

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Merge pull request #8479 from vishh/OOM

Provide Out Of Memory information in container status
Merge pull request #9105 from stevenburgess/archiveCommentFix

Fix comment to match the arg name
Adding Vish as a maintainer for daemon code.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)
Merge pull request #9127 from vishh/maintainer

Adding Vish as a maintainer for daemon.
Merge pull request #9124 from erikh/secure-localhost

Secure localhost registry (carry of #8898)
Merge pull request #9031 from cpuguy83/cleanup_api_server_creation

Cleanup api server creation
Merge pull request #8982 from rhvgoyal/save-restore-device-id

Save restore device Id: issue #8978