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Practical tutorials for the work we actually do. Pick one, read it in order, and apply it.

Any category Programming161 Python 32 JavaScript 33 TypeScript 32 SQL 32 HTML and CSS 32 DevOps32 Docker 32
Any topics APIs and Integrations 12 Automation and Scripting 6 Data Structures and Algorithms 8 Databases 32 Deployment and Containers 36 Object-Oriented Programming 7 Packaging and Dependencies 17 Performance Optimization 27 Programming Basics 18 Programming Patterns 12 Security 8 Testing and Debugging 36 Type Systems 35 Web Development 38
Any level Beginner 60 Intermediate 66 Advanced 67
193 results
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Tag an Image With a Version and latest

Tag one build with a version, latest and a commit name, then release the next version without moving the old tag. After this, you can roll back with one command.

3 min read
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Wait for a Dependency With a Healthcheck

Add a pg_isready health check to a database and make the app wait for it with service_healthy. After this, you can stop an app from failing on a database that is still starting.

3 min read
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Cut Rebuild Time With a BuildKit Cache Mount

Add a BuildKit cache mount to pip install so a changed requirements file downloads only the new packages. After this, a dependency change no longer means downloading everything again.

4 min read
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Multi-Stage Node or Go Image Under 50 MB

Build a Go service in a multi-stage Dockerfile and ship it in an image well under 50 MB, with a non-root user and a health check. After this, you know why Go gets that small and Node does not.

4 min read
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Run the Container as a Non-Root User

Add a user to an image, give it only the folder it writes to, and fix the two permission errors you will most likely hit. After this, your containers stop running as root.

4 min read
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Pin a Base Image by Digest

Look up a base image digest, pin it in the FROM line, check the build used it and plan how to update it. After this, your builds are repeatable without missing security fixes.

3 min read
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Add a HEALTHCHECK That Actually Fails

Break an app on purpose and compare three health checks, then put the one that works in the Dockerfile. After this, unhealthy means the app is broken, not the check.

5 min read
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Cap CPU and Memory So One Container Can't Starve the Host

Set CPU and memory limits, watch them work, change them on a running container and set them in Compose. After this, one busy container cannot take the whole machine.

4 min read
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Apply and Verify Log Rotation on an Existing Compose Service

Show why restart leaves old log settings in place, recreate one service with bounded logging, and verify retained messages without changing engine defaults.

7 min read
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Log In to a Private Registry From CI

Log in to a password-protected registry the way a CI job should, push an image, log out, and see the GitHub Actions version. After this, CI logins stop leaking tokens.

4 min read
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Read-Only Root Filesystem With a Writable tmpfs

Find where an app writes, run it read-only, and give it a tmpfs for scratch files and a volume for data. After this, nothing inside the container can change its own files.

4 min read
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Zero-Downtime Restart With Compose on One Host

Deploy a new version with blue and green copies, a proxy reload and a switch script, and prove no request failed. After this, a deployment on one host does not drop users.

4 min read