dd1d905371
hello.sh, Containerfile (Referenz) und commands.txt mit allen 6 Schritten inkl. Layer-Bonus. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
75 lines
2.7 KiB
Text
75 lines
2.7 KiB
Text
# Exercise 12a — Build a Containerfile step by step
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#
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# Start with an empty Containerfile and add one instruction at a time.
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# After each step: podman build -t myapp:latest .
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# Then inspect the result before moving on.
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cd listings/exercises/ex12a-containerfile-steps/
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# -----------------------------------------------------------------------
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# Step 1 — Base image
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# -----------------------------------------------------------------------
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# Containerfile:
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# FROM debian:12
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podman build -t myapp:latest .
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podman images myapp:latest # ~121 MB
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# -----------------------------------------------------------------------
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# Step 2 — Install software (creates a new layer)
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# -----------------------------------------------------------------------
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# Add to Containerfile:
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# RUN apt-get update && apt-get install -y curl
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podman build -t myapp:latest .
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podman images myapp:latest # ~159 MB — layer is visible
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# -----------------------------------------------------------------------
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# Step 3 — Working directory
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# -----------------------------------------------------------------------
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# Add to Containerfile:
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# WORKDIR /app
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podman build -t myapp:latest .
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podman run --rm myapp:latest pwd # prints /app
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# -----------------------------------------------------------------------
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# Step 4 — Copy your script into the image
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# -----------------------------------------------------------------------
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# Add to Containerfile:
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# COPY hello.sh .
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# RUN chmod +x hello.sh
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podman build -t myapp:latest .
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podman run --rm myapp:latest ls -la # hello.sh is there
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# -----------------------------------------------------------------------
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# Step 5 — Environment variable
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# -----------------------------------------------------------------------
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# Add to Containerfile:
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# ENV NAME=Trainee
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podman build -t myapp:latest .
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podman run --rm myapp:latest env | grep NAME
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# -----------------------------------------------------------------------
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# Step 6 — Start command
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# -----------------------------------------------------------------------
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# Add to Containerfile:
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# CMD ["./hello.sh"]
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podman build -t myapp:latest .
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podman run --rm myapp:latest # uses ENV NAME=Trainee
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podman run --rm -e NAME=Frank myapp:latest # override at runtime
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# -----------------------------------------------------------------------
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# Bonus: layers — chained vs. separate RUN
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# -----------------------------------------------------------------------
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# Two separate RUN = two layers:
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# RUN apt-get update
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# RUN apt-get install -y curl
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#
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# One chained RUN = one layer:
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# RUN apt-get update && apt-get install -y curl
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podman inspect myapp:latest --format '{{len .RootFS.Layers}} layers'
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