Deleting Unused Docker Volumes
Investigating Docker Volumes
While investigating migrating my kylemanna/openvpn image to use native Docker Volumes instead of the old busybox hack to create an empty volume I discovered I have a ton of dangling volumes. And consuming a ton of disk space.
What are they? What’s in them? Why are they dangling and not clean-up?
What’s in the Dangling Volumes?
Docker v1.9 added docker volume commands and later releases enhanced it. To query the dangling volumes:
$ docker volume ls -f dangling=true
DRIVER VOLUME NAME
local 0039d65be4c135d76340672bdff7e3b442ec65ef013aab486e60f111b37b4223
local 00c6dad23070368f18b963a8e4ee65f16b372969fa1a091c43ac41e500665a77
...
local fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3
local ff33f29a0ca8d60da171a6ead8966735856639a2e743793e83d0305f9d44eef7
In my case, I had 343 dangling volume containers.
$ docker volume ls -f dangling=true | wc -l
343
To check the total disk space:
$ docker volume ls -f dangling=true | awk '{print "/var/lib/docker/volumes/" $2 }' | xargs sudo du -hc
...
1.8G total
Dig deeper and sort them by disk space:
$ docker volume ls -f dangling=true | awk '{print "/var/lib/docker/volumes/" $2 }' | xargs sudo du -bs | sort -n
0 /var/lib/docker/volumes/_tmp
10 /var/lib/docker/volumes/12aea7b48bc182f4c108ba0a63f67a453249de3dcc30db046468b691f1ca88cf
10 /var/lib/docker/volumes/2b892d2094c16ab90d7536562be52d3816280f4288a6491bf1ec2e2f0b70deb4
205422216 /var/lib/docker/volumes/9a62b9bd1221926e5484782918161309113176ed411f04e95297e9cedc8eaea1
219513907 /var/lib/docker/volumes/adeb596ed11b2c6a62000a2abf7eb7ae868da64a9d0c11e2e3002e32d3187022
After reviewing the files in the biggest volumes it appears that I have some abandon volumes for MySQL databases for things I experimented with over a year ago.
No need for these anymore.
Delete the Old
Measure the size of my volumes directory before:
$ sudo du -hs /var/lib/docker/volumes
1.9G /var/lib/docker/volumes
Delete the Volumes Without Data
for i in $(docker volume ls -f dangling=true | awk '{print $2}'); do sudo test -d "/var/lib/docker/volumes/$i/_data" || echo docker volume rm $i; done
Note: Remove the echo from the above command to actually remove them. The echo was added to preview what would run.
This cleaned up 205 volumes for me.
Delete the data volumes without a _data directory as it appears there is little risk of losing anything.
Use my handy docker-cleanup script to examine and then delete the remaining directories:
git clone https://github.com/kylemanna/docker-cleanup.git
cd docker-cleanup
sudo ./docker-volume-cleanup.sh
Example output:
===========================================
:: Displaying fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3
===========================================
/var/lib/docker/volumes/fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3
└── _data
├── 9.4-main.pg_stat_tmp
│ ├── db_0.stat
│ ├── db_12141.stat
│ └── global.stat
└── 9.4-main.pid
2 directories, 4 files
creation: -
modification: 2015-10-19 18:21:37.187453160 -0700
size: 76K
Delete fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3? [y/N]: y
Executing: docker volume rm fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3
fe93d89dd4747e47098f69741e967626bed0ae35c7a12c541f4ce7b4ca043ea3
...
Measure the size of my volumes directory after cleanup:
$ sudo du -hs /var/lib/docker/volumes
169M /var/lib/docker/volumes
Dangling volume containers now: 0.
The Real Question
How’d this happen? Was there a bug or user error that didn’t clean these up? The oldest volumes are from 2014 and some as recent as last week.
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