cancelling a pull causes partially or fully downloaded layers to be discarded #26146
Description
I'm working from an unreliable network connection and sometimes I need to pull large images. When I'm pulling a large image and the wifi disconnects and then reconnects, the download hangs. Then I have to ctrl+c to cancel the pull and try it again. When I do this, all layers pulled during the previous attempt have to be re-pulled from scratch. This means that if I never have a stable connection for long enough to pull the entire image without interruptions I can't pull the image at all.
Output of docker version:
Client:
Version: 1.12.1-rc2
API version: 1.24
Go version: go1.6.3
Git commit: 236317f-unsupported
Built: Thu Aug 18 17:11:17 2016
OS/Arch: linux/amd64
Server:
Version: 1.12.1-rc2
API version: 1.24
Go version: go1.6.3
Git commit: 236317f-unsupported
Built: Thu Aug 18 17:11:17 2016
OS/Arch: linux/amd64
This is a slightly hacked up version, but the changes are not related. It's basically 1.12.1.
Output of docker info:
Containers: 10
Running: 10
Paused: 0
Stopped: 0
Images: 110
Server Version: 1.12.1-rc2
Storage Driver: overlay2
Backing Filesystem: extfs
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge null host overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 4.7.2-1-ARCH
Operating System: Arch Linux
OSType: linux
Architecture: x86_64
CPUs: 4
Total Memory: 7.708 GiB
Name: compooter
ID: GKSI:YHZC:YPNI:PAGO:EYPD:AYME:K6BY:BAIH:EBKQ:SOAK:WUFP:6MJM
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): true
File Descriptors: 62
Goroutines: 113
System Time: 2016-08-30T08:12:15.46410461-07:00
EventsListeners: 1
Username: viktorstanchev
Registry: https://index.docker.io/v1/
Cluster Store: etcd://172.17.0.1:12379
Cluster Advertise: 172.17.0.1:12376
Insecure Registries:
192.168.0.106
dtr2-2061409770.us-west-2.elb.amazonaws.com
new-1428125395.us-west-2.elb.amazonaws.com
172.17.0.1
127.0.0.0/8
Additional environment details (AWS, VirtualBox, physical, etc.):
physical laptop
Steps to reproduce the issue:
- pull a large image
- disconnect from the network and re-connect
- all layer downloads hang; ctrl+c to cancel
- pull again
Describe the results you received:
pulls from scratch
Describe the results you expected:
continues where it left off
Additional information you deem important (e.g. issue happens only occasionally):
This behaviour makes sense because otherwise a mechanism for cleaning up unused partial downloads is necessary, but I think that keeping these partial downloads around for about a day or some other arbitrary time period is reasonable.