Add a way to enable overcommit memory in docker-entrypoint

[Me-ion]

From https://redis.io/topics/admin:

Make sure to set the Linux kernel overcommit memory setting to 1

Can we add something like following in the docker-entrypoint script to be run before the redis server is started

if [[ "$ENABLE_OVERCOMMIT_MEMORY" == 'true' ]]; then
	echo 1 > /proc/sys/vm/overcommit_memory
fi

then it would be really easy to enable that with:

docker run \
    -e ENABLE_OVERCOMMIT_MEMORY=true \
    ....

that would make it so much easier than creating a custom image and/or entrypoint script

[yosifkit]

Related issues. #19, #20, #55; This value is not namespaced and so must be set on the host as the container cannot set it.

$ docker run -it --rm redis bash
root@deaa79bd3204:/# cat /proc/sys/vm/overcommit_memory 
0
root@deaa79bd3204:/# echo 1 > /proc/sys/vm/overcommit_memory 
bash: /proc/sys/vm/overcommit_memory: Read-only file system
root@deaa79bd3204:/# 

[tianon]

Another fun way to try and set this is via Docker's --sysctl flag which gives:

invalid argument "vm.overcommit_memory=1" for "--sysctl" flag: sysctl 'vm.overcommit_memory=1' is not whitelisted

[Adrian-Grimm]

Related issues. #19, #20, #55; This value is not namespaced and so must be set on the host as the container cannot set it.

$ docker run -it --rm redis bash
root@deaa79bd3204:/# cat /proc/sys/vm/overcommit_memory 
0
root@deaa79bd3204:/# echo 1 > /proc/sys/vm/overcommit_memory 
bash: /proc/sys/vm/overcommit_memory: Read-only file system
root@deaa79bd3204:/# 

echo "vm.overcommit_memory=1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

cat /proc/sys/vm/overcommit_memory