The first thing docker
build does is to send build context to Docker daemon, if the build
context is big, it can take a long time – so long that you doubt if it hangs. This
blog shares some practices I am doing to speed up building a docker image.
Speed up Vagrant
if you are hosting vagrant VMs on Windows, accessing sync
folder will be slow. There is a plugin https://github.com/winnfsd/vagrant-winnfsd
that adds NSF to Windows, unfortunately,
it doesn’t work for me: my McAfee blocks it.
There are some configurations that can speed up Vagrant:
config.vm.provider "virtualbox" do |v|
v.memory
=2048
v.cpus =
"2"
# change the
network card hardware for better performance
v.customize ["modifyvm", :id,
"--nictype1", "virtio" ]
v.customize
["modifyvm", :id, "--nictype2", "virtio" ]
# suggested
fix for slow network performance
# see
https://github.com/mitchellh/vagrant/issues/1807
v.customize ["modifyvm", :id,
"--natdnshostresolver1", "on"]
v.customize
["modifyvm", :id, "--natdnsproxy1", "on"]
end
.dockerignore
Add .dockerignore
in the build context, files defined in the file will be ignored by docker when
sending build context to the docker daemon.
echo ./server/log
> .dockerignore
echo ./server/tmp
>> .dockerignore
Change files in a running container
After you spend a lot of time building the docker image, you
may find that it doesn’t work out as you expected, perhaps some configuration
files are not setup correctly, you change those files, and then you need to
rebuild the image again, which is unbearable waste of time.
My approach is:
1)
Add a volume to the image, which will be used to
hold files to be copied to the container
VOLUME
["/942-docker-volume"]
Build the image
2)
Run a container, in the run command, mount the volume,
and switch the entrypoint
command. In the replaced entrypoint
command, copy files from the mounted volume to replace files in the container.
sudo
docker run -it --name pm942 -p 8080:8080
-v /942-docker-volume/home:/942-docker-volume/home --entrypoint /bin/sh pm942 -c "cp
/942-docker-volume/home/*.conf /pm942/ && cp
/942-docker-volume/home/bin/*.sh /pm942/bin/ && cd ./bin && ./Start.sh"
Notice the --entrypoint
parameter, whose value is “/bin/sh”.
Also notice the argument to “/bin/sh”
is placed at the end, after the image name pm942.
This --entrypoint command copies
files from the mounted volume and replace files accordingly inside the
container.
Or you can ignore the argument, and thus log into the container
to manipulate it:
sudo docker run -it
--name pm942 -p 8080:8080 -v
/942-docker-volume/home:/942-docker-volume/home --entrypoint
/bin/sh pm942
