Course 31 - Dive Into Docker | Episode 6: A Hands-On Guide to Dockerizing Web Applications

In this lesson, you’ll learn about: dockerizing a web app, writing Dockerfiles, and optimizing builds1. The Application Architecture (Real-World Example)This lab uses a simple microservices setup:Flask web application (frontend/API)Redis (backend datastore)Key idea:Each service runs in its own containerThey communicate over a Docker network👉 This mirrors real production systems (microservices architecture)2. Writing a Dockerfile from ScratchA Dockerfile is the blueprint for building an image in Docker.🧱 FROM — Base ImageFROM python:2.7-alpineUses an official imageAlpine = very small size → faster builds & less storage⚙️ RUN — Execute CommandsRUN mkdir /appRuns shell commands inside the imageTypically used for:Installing dependenciesPreparing the environment📁 WORKDIR — Set Working DirectoryWORKDIR /appDefines where commands will runAvoids hardcoding full paths everywhere📦 COPY — Add Files to ImageCOPY . .Copies your application code into the containerIncludes:Source codeRequirements file3. Build Optimization (Layer Caching)Docker builds images in layersOrder of instructions matters a lot✅ Optimized Approach:COPY requirements.txt . RUN pip install -r requirements.txt COPY . .Why?Dependencies don’t change oftenDocker caches this layerRebuilds become much faster4. Metadata with LABELLABEL maintainer="[email protected]"Adds useful metadata:AuthorVersionDescription👉 Helpful for team environments and production tracking5. Running the Application with CMDCMD ["python", "app.py"]Defines the default command when the container startsIn this case:Launches the Flask app on port 50006. How Everything Works TogetherBuild the image:docker build -t myapp .Run the container:docker run -p 5000:5000 myappAccess app:Open browser → localhost:50007. Key Concepts You Just LearnedHow to dockerize a real applicationCore Dockerfile instructions:FROM, RUN, WORKDIR, COPY, LABEL, CMDHow layer caching speeds up buildsHow services like Flask + Redis work together in containersKey TakeawaysDockerfile = reproducible build recipeInstruction order = performance optimizationContainers isolate services cleanlyThis workflow is used in:DevOpsCI/CDCloud deploymentsYou can listen and download our episodes for free on more than 10 different platforms:https://linktr.ee/cybercode_academy