In order to test the Docker images pruning with Openshift Origin I made the following test.

Environment:

• Two nodes, one master + infra and a workload node.
• Cluster version: Openshift Origin 3.6

First of all I have built a Docker image based on NodeJS within a large file. The file.out is of 50M and after compression it decreases little.

Structure of my NodeJS app

[root@origin-master nodeapp]# ls -lhas

total 51M

 0 drwxr-xr-x. 2 root root 106 May 27 16:41 .

 0 drwx------. 6 vagrant vagrant 228 May 27 09:09 ..

4.0K -rw-r--r--. 1 root root 136 May 27 16:22 Dockerfile

4.0K -rw-r--r--. 1 root root 261 May 27 16:18 create_fake_images.sh

 50M -rw-r--r--. 1 root root 50M May 27 16:18 file.out

4.0K -rw-r--r--. 1 root root 265 May 27 09:09 package.json

4.0K -rw-r--r--. 1 root root 539 May 27 15:19 server.js

The Dockerfile is very simple!

[root@origin-master nodeapp]# cat Dockerfile

FROM node

# Create app directory

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 8080

CMD [ "npm", "start" ]

The following script helped me to generate many images with additional and differents layers. Each iterations copy the 50M file inside the image.

for i in $(seq 1 1000)

do

 echo "RUN echo $i" >> Dockerfile

 echo "COPY file.out ./$i.out" >> Dockerfile

 docker build -t docker-registry-default.origin.local/test/nodeapp:latest .

 docker push docker-registry-default.origin.local/test/nodeapp:latest

done

Let's see how the Docker registry folder increase size during create_fake_images.sh execution.

1a4c7633d886: Pushing [=======> ] 8.325 MB/52.43 MB

e36035decad2: Pushing [=======> ] 7.768 MB/52.43 MB

bb1e26b5f124: Pushing [=======> ] 7.768 MB/52.43 MB

13c3d2712668: Pushing [===========> ] 11.67 MB/52.43 MB

dbc4876ab96c: Pushing [=======> ] 8.327 MB/52.43 MB

[root@origin-master vagrant]# du -chs /data/origin/

 782M /data/origin/

 782M total

[root@origin-master vagrant]# du -chs /data/origin/

 956M /data/origin/

 956M total

[root@origin-master vagrant]# du -chs /data/origin/

 1.2G /data/origin/

 1.2G total

Describing image stream nodeapp we can see the latest images pushed to the registry

[root@origin-master nodeapp]# oc describe is

Name: nodeapp

Namespace: test

Created: 2 hours ago

Labels: <none>

Annotations: <none>

Docker Pull Spec: docker-registry.default.svc:5000/test/nodeapp

Image Lookup: local=false

Unique Images: 5

Tags: 1

latest

 pushed image

* docker-registry.default.svc:5000/test/nodeapp@sha256:6f517f2bd667280587daebd57c456c723df4e97d72903100cad441821203e4ec

 22 seconds ago

 docker-registry.default.svc:5000/test/nodeapp@sha256:421155780252a908de9c4968c65a508c65b12b259a6248278b73dd20edee20fb

 About a minute ago

 docker-registry.default.svc:5000/test/nodeapp@sha256:b26f1d2cac95a73632891a6cfec875baed0b1a4165c381e59e0ce4d1bfc403f9

 About a minute ago

 docker-registry.default.svc:5000/test/nodeapp@sha256:6d6f63093aae64198fb1d7af2cd2a361cec991817c8e6944910cb84420a52c1b

 20 minutes ago

 docker-registry.default.svc:5000/test/nodeapp@sha256:6e82ae61a154788ff70ff3ed69cf3a088845e0c7c2d1441de4123c213a0f0116

 23 minutes ago

I changed the Dockerfile in order to have an image that does not import large file. So I have built and pushed the following Docker image

[root@origin-master nodeapp]# cat Dockerfile

FROM node

# Create app directory

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 8080

CMD [ "npm", "start" ]

Let’s start to prune

1. Delete old deployments

[root@origin-master nodeapp]# oc adm prune deployments --orphans --keep-complete=1 --keep-failed=1 --keep-younger-than=1m

Dry run enabled - no modifications will be made. Add --confirm to remove deployments

NAMESPACE NAME

test nodeapp2-23

test nodeapp2-22

test nodeapp2-21

test nodeapp2-20

1. Prune the unused images and keep only one revision

[root@origin-master nodeapp]# oc adm prune images --keep-tag-revisions=1 --keep-younger-than=1m --confirm

Deleting references from image streams to images ...

STREAM IMAGE TAGS

test/nodeapp sha256:6e82ae61a154788ff70ff3ed69cf3a088845e0c7c2d1441de4123c213a0f0116 latest

test/nodeapp sha256:421155780252a908de9c4968c65a508c65b12b259a6248278b73dd20edee20fb latest

test/nodeapp sha256:b26f1d2cac95a73632891a6cfec875baed0b1a4165c381e59e0ce4d1bfc403f9 latest

Deleting registry repository layer links ...

REPO LAYER LINK

test/nodeapp sha256:3de138bf364bf3e2684c78468d07a0e2ca786ba08f83bd1b7e3373a1e0b407e5

test/nodeapp sha256:a75ed4d808fc563081de632debf91580a6dbe6d694971ca6888b5be4433f55cc

test/nodeapp sha256:677e3bfb00ad311212b46be4ddb20f5b762765fef676c6d4a85e5dbcb943c4a4

test/nodeapp sha256:29510362ff8e174edf88563f6099141b9e82efd5cd48b14aeaa74fea532e6d43

test/nodeapp sha256:35dc109c74dfcab9f1f027ccc1404e7ef3f524d6efea226e3920959051819f2c

test/nodeapp sha256:f3d40164b23c42356d717da92b91774402632a8df22cd5ddfb7926fc3a7292f6

test/nodeapp sha256:fe03b24c2c84648d09331dbd72a8065b8ed550be991155edc72ad1166f1ef666

test/nodeapp sha256:8eaf1a821a6b8a2e325cebce83311c5d3b33427140d84954f504ed59bab51109

test/nodeapp sha256:684c30e67a270d2115cb4be1c9712193bf0b4393ffa04b3c625e76fadd6bda12

test/nodeapp sha256:7d6ad63a8e94a938a95fa1e27106bbc7ecfa3680b3ff3a11c7bdb43ae610eb18

test/nodeapp sha256:e1614bf81372b99eb86c74ac9c023c01077061db81c4daeaf6683e27299e48cc

test/nodeapp sha256:a92bff6ede96a89a94fe2ca794115e1c374312d05e895698e6b1638c3b647645

test/nodeapp sha256:2d9ccccdee639671c6cb24110e529b738535453a3ccdf68989ac31ea6894929d

test/nodeapp sha256:1e920f3f2676bc50c60a95c9d8710cb91429ab07278616c02680b0f38af2d224

test/nodeapp sha256:90b58c4583c3de52b6f6762c83a02d42dd18747a2541bafb483a9cdbc5e55f8b

test/nodeapp sha256:d041de45e8895ee77b4e6ba112959e361d888b5694910b44f54fb88f0ef3fb4f

Deleting registry layer blobs ...

BLOB

sha256:3de138bf364bf3e2684c78468d07a0e2ca786ba08f83bd1b7e3373a1e0b407e5

sha256:a75ed4d808fc563081de632debf91580a6dbe6d694971ca6888b5be4433f55cc

sha256:677e3bfb00ad311212b46be4ddb20f5b762765fef676c6d4a85e5dbcb943c4a4

sha256:29510362ff8e174edf88563f6099141b9e82efd5cd48b14aeaa74fea532e6d43

sha256:35dc109c74dfcab9f1f027ccc1404e7ef3f524d6efea226e3920959051819f2c

sha256:f3d40164b23c42356d717da92b91774402632a8df22cd5ddfb7926fc3a7292f6

sha256:fe03b24c2c84648d09331dbd72a8065b8ed550be991155edc72ad1166f1ef666

sha256:8eaf1a821a6b8a2e325cebce83311c5d3b33427140d84954f504ed59bab51109

sha256:684c30e67a270d2115cb4be1c9712193bf0b4393ffa04b3c625e76fadd6bda12

sha256:7d6ad63a8e94a938a95fa1e27106bbc7ecfa3680b3ff3a11c7bdb43ae610eb18

sha256:e1614bf81372b99eb86c74ac9c023c01077061db81c4daeaf6683e27299e48cc

sha256:a92bff6ede96a89a94fe2ca794115e1c374312d05e895698e6b1638c3b647645

sha256:2d9ccccdee639671c6cb24110e529b738535453a3ccdf68989ac31ea6894929d

sha256:1e920f3f2676bc50c60a95c9d8710cb91429ab07278616c02680b0f38af2d224

sha256:90b58c4583c3de52b6f6762c83a02d42dd18747a2541bafb483a9cdbc5e55f8b

sha256:d041de45e8895ee77b4e6ba112959e361d888b5694910b44f54fb88f0ef3fb4f

Deleting registry repository manifest data ...

REPO IMAGE

test/nodeapp sha256:6e82ae61a154788ff70ff3ed69cf3a088845e0c7c2d1441de4123c213a0f0116

test/nodeapp sha256:421155780252a908de9c4968c65a508c65b12b259a6248278b73dd20edee20fb

test/nodeapp sha256:b26f1d2cac95a73632891a6cfec875baed0b1a4165c381e59e0ce4d1bfc403f9

Deleting images from server ...

IMAGE

sha256:6e82ae61a154788ff70ff3ed69cf3a088845e0c7c2d1441de4123c213a0f0116

sha256:421155780252a908de9c4968c65a508c65b12b259a6248278b73dd20edee20fb

sha256:b26f1d2cac95a73632891a6cfec875baed0b1a4165c381e59e0ce4d1bfc403f9

Check the size of  registry folder

[root@origin-master nodeapp]# du -chs /data/origin/
608M /data/origin/
608M total

Ok from 1.6gb we went down to 608M !