CODEWITHSUNDEEP
docker
ricksebak
ricksebak

Reputation: 63

Possible to fake cpu and memory inside a Docker container?

I have a CICD server which builds Docker images and pushes them to an image repo. All it really does is docker build && docker push, it doesn’t run any of the workloads of those images, and as such it’s a small-ish cloud instance.

I’d like to use it to build an image where it installs a package by way of RUN yum install -y somepackage.rpm, but the package I’m installing does a cpu and memory check and it refuses to install when less than X cpu cores and Y gigs of memory are present, and my CICD server doesn’t meet those thresholds. It makes sense that I’ll need to meet those thresholds when I actually run this image/workload on another server, but I’d like to work around that limit when all I’m doing is building the image.

Is it possible to fake cpu cores and memory inside the build context? Could I somehow expose 8 CPU’s or whatever inside a container when the host only has 2?

Upvotes: 0

Views: 906

Answers (1)

Fred Phillips
Fred Phillips

Reputation: 11

It depends on how it does the check. Often it will look at 2 things.

free -m (or -g) and cat /proc/cpuinfo then it will grep for something, so you fake the output with an echo and replace mem and proc with the appropriate amount

echo " total used free shared buff/cache available Mem: 32417152 12002948 16547220 48080 3866984 19974332 Swap: 12582908 0 12582908"

Paste this script into the command line then run your install.

cd /usr/bin 
mv nproc nproc2 
mv free free2 
echo "16" > nproc 
chmod +x nproc 
echo "              total        used        free      shared          buff/cache   available" > free 
echo " Mem:             64  
    0          48           0          11          39 " >> free 

echo "Swap:            11           0          11" >> free 
chmod +x free

Upvotes: 1

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