Speed up deployment by mounting files at run instead of copying them at build

[isartcanyameres]

Instead of copying files at the build, you can mount it at the run with -v option. (-v /home/CNSMO/ENVS/VPNClient-slave.1/client.conf:/etc/openvpn/client.conf:ro)
Multiple files can be mounted.
If files are mounted, you could publish the container on a public repo and get it instead of compiling it.
Doing this can speed up the deployment significantly (compiling the docker can be very slow).
To check the time saved use command :
time docker build --no-cache -t client-vpn .

An example of use can be found here:
https://github.com/cyclone-project/federated-filtering-proxy-with-docker/blob/master/startFilteringProxy.sh#L54

[bryan-brancotte]

Here after some test for COPY vs mount
tl;dr: COPY takes 27s while mount 18

Details and commands used:

#with COPY
time docker build -f Dockerfile --no-cache -t client-vpn . 1>/dev/null

real 0m27.424s
user 0m0.027s
sys 0m0.015s
docker rm -f $(docker ps -aq)

docker rm -f $(docker ps -aq)
time docker run --net=host  --privileged -v /dev/net/:/dev/net/ \
--name client-vpn -d client-vpn

real 0m0.306s
user 0m0.007s
sys 0m0.006s

#with mount
cat Dockerfile | grep -v COPY > Dockerfile.noCOPY
time docker build -f Dockerfile.noCOPY --no-cache -t client-vpn . 1>/dev/null

real 0m18.205s
user 0m0.018s
sys 0m0.010s
docker rm -f $(docker ps -aq)

docker rm -f $(docker ps -aq)
time docker run --net=host  --privileged -v /dev/net/:/dev/net/ \
 -v /home/CNSMO/ENVS/VPNClient-slave.1/client.conf:/etc/openvpn/client.conf:ro \
 -v /home/CNSMO/ENVS/VPNClient-slave.1/client.crt:/etc/openvpn/client.crt:ro \
 -v /home/CNSMO/ENVS/VPNClient-slave.1/ca.crt:/etc/openvpn/ca.crt:ro \
 -v /home/CNSMO/ENVS/VPNClient-slave.1/client.key:/etc/openvpn/client.key:ro \
 -v /home/CNSMO/ENVS/VPNClient-slave.1/tun_manager.sh:/etc/openvpn/tun_manager.sh:ro \
--name client-vpn -d client-vpn

real 0m0.341s
user 0m0.022s
sys 0m0.014s