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>
Format the source according to latest goimports.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This reverts commit 98fc09128b in order to
keep registry v2 schema1 handling and libtrust-key-based engine ID.
Because registry v2 schema1 was not officially deprecated and
registries are still relying on it, this patch puts its logic back.
However, registry v1 relics are not added back since v1 logic has been
removed a while ago.
This also fixes an engine upgrade issue in a swarm cluster. It was relying
on the Engine ID to be the same upon upgrade, but the mentioned commit
modified the logic to use UUID and from a different file.
Since the libtrust key is always needed to support v2 schema1 pushes,
that the old engine ID is based on the libtrust key, and that the engine ID
needs to be conserved across upgrades, adding a UUID-based engine ID logic
seems to add more complexity than it solves the problems.
Hence reverting the engine ID changes as well.
Signed-off-by: Tibor Vass <tibor@docker.com>
As people are using the UUID in `docker info` that was based on the v1 manifest signing key, replace
with a UUID instead.
Remove deprecated `--disable-legacy-registry` option that was scheduled to be removed in 18.03.
Signed-off-by: Justin Cormack <justin.cormack@docker.com>
In info, we only need the number of images, but `CountImages` was
getting the whole map of images and then grabbing the length from that.
This causes a lot of unnecessary CPU usage and memory allocations, which
increases with O(n) on the number of images.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
