docs(dhi): add .NET and Java migration examples#25201
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Adds before/after Dockerfile examples for migrating .NET and Java applications to Docker Hardened Images, following the existing Go/Python/Node.js examples format. Updates the examples index grid to include the new guides. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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/review |
docker-agent
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Assessment: 🔴 CRITICAL
Two confirmed accuracy bugs in the new Dockerfile examples that would mislead users:
- java.md —
Before (Ubuntu)uses a JRE image as the build stage, but JRE images lackjavacand Maven, somvn -B packagewould fail. - dotnet.md —
After (single-stage)has a redundantcpstep afterdotnet publish -o /app. Since-o /appredirects output directly to/app, the source path/src/bin/Release/net8.0/publish/doesn't exist. The2>/dev/null || truesilently suppresses the failure, producing a potentially broken image with no error.
craig-osterhout
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craig-osterhout
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Thank you for raising this.
It looks like the existing examples, that this was based on, are using OS versions that are no longer available. I can get those updated.
For this PR, please ensure all new examples are able to run. The following repo is from an agent that tried to run samples. It includes the suggested fixes.
Thanks @craig-osterhout for reviewing, let me check that |
Apply verified fixes from craig-osterhout/dotnet-java-dhi-verify so the .NET and Java migration examples actually build and run. Java (java.md): - Before (Ubuntu): switch builder + runtime to ubuntu:24.04 and install JDK/Maven (and JRE) via apt. The ubuntu/jre and ubuntu/jdk Pebble-based images have no shell or mvn and fail mvn -B package immediately. - After (multi-stage): update DHI image refs to dhi.io/maven:3-jdk21-alpine3.22-dev and dhi.io/eclipse-temurin:21-alpine3.22 (the alpine3.21 tags do not exist). - After (single-stage): same maven image update. .NET (dotnet.md): - Remove the Before (Ubuntu) tab. ubuntu/dotnet-sdk:8.0-24.04 does not exist; Canonical does not publish a .NET SDK image. Update the intro to describe four variations instead of five. - Before (Wolfi): publish to /src/out and COPY from there. Chainguard images run as non-root and cannot create /app at publish time. - After (multi-stage): update DHI image refs to dhi.io/dotnet:8-sdk-alpine3.22 and dhi.io/aspnetcore:8-alpine3.22. - After (single-stage): update DHI image ref and remove redundant cp -r /src/bin/.../publish/* /app/ 2>/dev/null || true step, since dotnet publish -o /app already writes directly to /app. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…examples Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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/review |
@craig-osterhout I looked at your repo, updated my PR accordingly and I also ran examples (built 9 images), to make sure everything works as expected, here are some screenshots. For java, 
Docker desktop showing Java images: For Dotnet, 
Docker desktop showing Dotnet images : 
Let me know if you have any other comments. |
@craig-osterhout , btw how to trigger the review ? looks like I dont have permissions to trigger docker agent ? |
4 participants
This PR adds two new migration example guides under
content/manuals/dhi/migration/examples/for migrating applications to Docker Hardened Images (DHI):dotnet.md)java.md)Both guides follow the exact same structure as the existing Go, Python, and Node.js examples, with five Dockerfile variations each:
The .NET guide uses
dhi.io/dotnet-sdkfor build anddhi.io/dotnet-aspnetfor runtime. The Java guide usesdhi.io/mavenfor build anddhi.io/eclipse-temurinfor runtime.The
_index.mdgrid is updated to surface both new examples on the Migration examples landing page.Checklist
dhi.io/dotnet-sdk,dhi.io/dotnet-aspnet,dhi.io/maven,dhi.io/eclipse-temurin)_index.md)