Posted on Dec 28, 2021

Docker - Messing/Mixing/Duplicating application variables in memory inside running containers.

Hi!

I'm facing an issue with running docker containers by docker-compose. Before writing here, I tried all possible solutions, did research in google an so on. Still no luck! Hope, folks here can help me to figure out my issue related to docker running containers.

Expected behavior

Running 4 containers from same image
Application running in docker container generates random data and creates json string.
Each application running inside containers should generate/create unique values inside docker containers.

Actual behavior

Running 4 containers from same image
Applications running inside docker containers mixing a values and almost 70% is the same value.
Assuming, issue with containers "shared" memory.
Same application(s) running outside of docker container works perfect and generates unique values.

Tested with PHP, Node.js, Golang. The issue is the same.

Steps to reproduce the behavior

It's very complicated to reproduce the issue.
But in some words you can imagine:

Without docker containers creation, running 4 copies of the same application: Generates unique random values.

Inside docker containers, applications running and 70% of values is the same.
Assuming, a problem comes from container's memory stack.

Using docker-compose to deploy containers:

all 4 containers using the same image

container A Using Image "Myimg" container B Using Image "Myimg" container C Using Image "Myimg" container D Using Image "Myimg"

Output of docker version:

Docker version 20.10.12, build e91ed57

Output of docker info:

Client: Context: default Debug Mode: false Plugins: app: Docker App (Docker Inc., v0.9.1-beta3) buildx: Docker Buildx (Docker Inc., v0.7.1-docker) scan: Docker Scan (Docker Inc., v0.12.0) Server: Containers: 8 Running: 6 Paused: 0 Stopped: 2 Images: 41 Server Version: 20.10.12 Storage Driver: overlay2 Backing Filesystem: extfs Supports d_type: true Native Overlay Diff: true userxattr: false Logging Driver: json-file Cgroup Driver: systemd Cgroup Version: 2 Plugins: Volume: local Network: bridge host ipvlan macvlan null overlay Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog Swarm: inactive Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc Default Runtime: runc Init Binary: docker-init containerd version: 7b11cfaabd73bb80907dd23182b9347b4245eb5d runc version: v1.0.2-0-g52b36a2 init version: de40ad0 Security Options: apparmor seccomp Profile: default cgroupns Kernel Version: 5.13.0-22-generic Operating System: Ubuntu 21.10 OSType: linux Architecture: x86_64 CPUs: 4 Total Memory: 15.54GiB Name: david-Macmini ID: FNY6:BSVD:L7JK:BFCW:ZCMP:6OMK:HM3I:U22T:WB2W:FCXM:4WC5:XS7B Docker Root Dir: /var/lib/docker Debug Mode: false Registry: https://index.docker.io/v1/ Labels: Experimental: false Insecure Registries: 127.0.0.0/8 Live Restore Enabled: false

Running the docker in: Ubuntu 21.10 ( bare metal )