How to Audit and Optimize Dockerfile Build Times and Image Sizes
Designed for Mid-level DevOps engineers and software developers responsible for maintaining CI/CD pipelines and containerized applications in high-velocity product teams to spark real collaboration and high-energy learning.
A 90-minute, hands-on virtual workshop for DevOps and development teams experiencing sluggish deployment cycles and security concerns due to bloated Docker images. Attendees are frustrated by slow feedback loops and find it challenging to identify the root causes of inefficiency in their existing Dockerfiles. The format alternates between practical demos, interactive discussions, and real-world auditing exercises.
Dockerfile Detective: What Slows You Down?
Kick off with a quick-fire poll: Present three anonymized Dockerfile snippets and ask, 'Which one do you think takes the longest to build, and why?' Allow participants to guess, then reveal the surprising answer—often, the culprit isn’t the most obvious. This sparks curiosity and primes the group for deeper exploration.
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Why this works
Starting with a puzzle leverages curiosity to motivate learning, and helps surface pre-existing mental models about Dockerfile optimization.
Mythbusting Docker Layers
Display four common Dockerfile optimization beliefs (e.g., 'The number of layers is always bad'). Ask participants to vote 'fact' or 'myth'. Debrief each statement with a quick explanation and real-life counterexample, smashing misconceptions that hinder efficient builds.
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Why this works
Addressing and correcting misconceptions leads to more effective learning by replacing faulty mental models with accurate conceptual understanding.
Fastest Finger: Build Time Bingo
Share a list of 10 quick Dockerfile tweaks (e.g., 'Combine RUN commands,' 'Use .dockerignore'). Ask each participant to type in chat which ones they already use—no wrong answers. Then, highlight the most and least common practices to spark inclusive, low-pressure sharing.
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Why this works
Low-stakes participation increases psychological safety, helping all voices be heard and making it easy to surface knowledge gaps without judgment.
Dockerfile Refactor Showdown
Split attendees into breakout groups and assign each a messy Dockerfile. Challenge them to optimize it for speed and size in 5 minutes. Groups then share their top tweak in a rapid-fire round, fostering healthy competition and high energy.
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Why this works
Active problem-solving in small teams builds confidence and energy while making abstract concepts tangible through immediate application.
CI/CD Pipeline Dilemma
Pose a realistic scenario: 'Your automated builds are now taking 30 minutes, blocking your deploys. You must choose: delay features, risk cutting corners, or investigate the Dockerfile.' Facilitate a guided discussion about the real trade-offs technical teams face, and how image size impacts business goals.
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Why this works
Anchoring technical issues in real business pressures increases relevance and urgency, making abstract optimization feel critical.
Personal Dockerfile Pledge
Invite each participant to reflect: 'What’s one Dockerfile optimization you’ll try in your next sprint?' Have them write it down privately, then optionally share in chat or on a sticky note wall. This closes the loop between learning and action.
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Why this works
Personal commitment cements learning by bridging the gap between workshop insights and real-world behavior, increasing follow-through.
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