Moby works perfectly when you are in a situation when one has a good and stable
internet connection. Operating in area's where internet connectivity is likely
to be lost in undetermined intervals, like a satellite connection or 4G/LTE in
rural area's, can become a problem when pulling a new image. When connection is
lost while image layers are being pulled, Moby will try to reconnect up to 5 times.
If this fails, the incompletely downloaded layers are lost will need to be completely
downloaded again during the next pull request. This means that we are using more
data than we might have to.
Pulling a layer multiple times from the start can become costly over a satellite
or 4G/LTE connection. As these techniques (especially 4G) quite common in IoT and
Moby is used to run Azure IoT Edge devices, I would like to add a settable maximum
download attempts. The maximum download attempts is currently set at 5
(distribution/xfer/download.go). I would like to change this constant to a variable
that the user can set. The default will still be 5, so nothing will change from
the current version unless specified when starting the daemon with the added flag
or in the config file.
I added a default value of 5 for DefaultMaxDownloadAttempts and a settable
max-download-attempts in the daemon config file. It is also added to the config
of dockerd so it can be set with a flag when starting the daemon. This value gets
stored in the imageService of the daemon when it is initiated and can be passed
to the NewLayerDownloadManager as a parameter. It will be stored in the
LayerDownloadManager when initiated. This enables us to set the max amount of
retries in makeDownoadFunc equal to the max download attempts.
I also added some tests that are based on maxConcurrentDownloads/maxConcurrentUploads.
You can pull this version and test in a development container. Either create a config
`file /etc/docker/daemon.json` with `{"max-download-attempts"=3}``, or use
`dockerd --max-download-attempts=3 -D &` to start up the dockerd. Start downloading
a container and disconnect from the internet whilst downloading. The result would
be that it stops pulling after three attempts.
Signed-off-by: Lukas Heeren <lukas-heeren@hotmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Support for duplicate labels (but different values) was
deprecated in commit e4c9079d09
(Docker 1.13), and scheduled for removal in 17.12
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Before this commit if "--config-file" wasn't set the daemon would use
the default configuration file which is "/etc/docker/daemon.json".
When attempting to reload the daemon if that file didn't exist
and error message would display.
This behaviour is changed in a way that if the default configuration
file does not exist and no other configuration file is set
the daemon uses an empty configuration which later will be updated
and reloaded using the "reload" function given as an argument in Reload.
However, if the "--config-file" is set and the file is removed
or renamed an error message will be displayed and no reload will be done.
Signed-off-by: Boaz Shuster <ripcurld.github@gmail.com>
I noticed that we're using a homegrown package for assertions. The
functions are extremely similar to testify, but with enough slight
differences to be confusing (for example, Equal takes its arguments in a
different order). We already vendor testify, and it's used in a few
places by tests.
I also found some problems with pkg/testutil/assert. For example, the
NotNil function seems to be broken. It checks the argument against
"nil", which only works for an interface. If you pass in a nil map or
slice, the equality check will fail.
In the interest of avoiding NIH, I'm proposing replacing
pkg/testutil/assert with testify. The test code looks almost the same,
but we avoid the confusion of having two similar but slightly different
assertion packages, and having to maintain our own package instead of
using a commonly-used one.
In the process, I found a few places where the tests should halt if an
assertion fails, so I've made those cases (that I noticed) use "require"
instead of "assert", and I've vendored the "require" package from
testify alongside the already-present "assert" package.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
This also moves some cli specific in `cmd/dockerd` as it does not
really belong to the `daemon/config` package.
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Sebastiaan van Stijn