Docker Certified Associate case studies
DCA · Put your knowledge to work in context.
The Docker Certified Associate (DCA) is a vendor certification aimed at practitioners who build, ship, and run containerized applications using Docker tooling. Candidates typically come from DevOps, platform, and application-development roles, and are expected to be comfortable with the Docker CLI, image workflows, and multi-container deployments rather than with a single product feature. The DCA case studies are 5 cases and about 4,659 words.
1The rollout that parked itself at 50%
A swarm has three managers and two workers. Service checkout runs 8 replicas of checkout:1 , published on port 443.
859 words, about 4 min21.6 GB images and three nodes that distrust the registry
CI builds a Python API from a repo whose Dockerfile does COPY . /app and then RUN pip install -r requirements.txt .
837 words, about 4 min3Small requests fly, large uploads hang across nodes
Three nodes share one VLAN. Two were rebuilt last month with "mtu": 9000 in /etc/docker/daemon.json to match a jumbo-frame storage fabric; the third still runs stock config.
945 words, about 5 min4A production password in a public repo, an image layer, and an env var
An audit of a stack deployed with docker stack deploy -c docker-compose.yml prod finds: POSTGRES PASSWORD: Pr0d-S3cr3t under environment: in a repo with 14 contributors; containers running as root with default capabilities and a writable root filesystem; an image reference of postgres:latest ; and an older tag still sitting in the internal registry whose layer contains an .env file with the same password. The application reads PGPASSWORD and DATABASE URL from the environment.
1,019 words, about 5 min5Four replicas, four different upload directories
A four-node swarm runs web with 4 replicas using --mount type=volume,source=uploads,target=/app/uploads . Nobody ever ran docker volume create , so each node auto-created its own uploads the first time a task landed there.
999 words, about 5 min