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49 lines
1.4 KiB
Markdown
49 lines
1.4 KiB
Markdown
---
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title: "Advanced Docker Image Construction with Bash"
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date: 2019-12-26T21:01:37-05:00
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draft: false
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tags: [ "Linux", "Containers" ]
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medium_enabled: true
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---
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On current versions of Docker, you can't mount volumes during image construction. This poses an issue for me as I don't want to replicate gigabytes of data already existing on my disk when it won't appear on the final build. Therefore, instead of building an image with a traditional Dockerfile, we're going to use a bash script on a running base image container and export the filesystem to create the image from.
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So first run the base image with the mounts that you want
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```bash
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docker run -v /mnt:/mnt -td --name containername baseimage /bin/bash
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```
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Then copy whatever `setup` script you have and execute it on the running container
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```bash
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docker cp setup containername:/setup
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docker exec -it containername /setup
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```
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Once the setup script finalizes, we can export the container filesystem into a file called `image.tar`
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```bash
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docker export --output="image.tar" containername
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```
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Once we've exported the filesystem, we can get rid of the existing container
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```bash
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docker stop containername && docker rm containername
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```
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Now create a `Dockerfile` with the following:
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```dockerfile
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FROM scratch
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ADD image.tar /
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CMD ["bin/bash"]
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```
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Now you can create the image by building the Dockerfile
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```bash
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docker build -t finalimagename .
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```
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