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https://github.com/mudler/docker-companion

squash and unpack Docker images, in Golang
https://github.com/mudler/docker-companion

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squash and unpack Docker images, in Golang

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# docker-companion [![Build Status](https://travis-ci.org/mudler/docker-companion.svg?branch=master)](https://travis-ci.org/mudler/docker-companion)



docker-companion is a candy mix of tools for docker written in Golang and directly using Docker API calls. As for now it allows to squash and unpack an image.



## Reinventing the wheel?



Problem arises with current tools to squash/unpack images since mostly of them are scripted. I personally needed a static implementation with no-deps hell that i could use in my CI pipeline easily (and also to get the job done).



## Download and unpack image 



Note: Doesn't require a docker daemon running on the host.



    docker-companion download my-awesome-image /unpacked_rootfs

    

Downloads and reconstruct all the image layers,

unpacking the content to the directory given as second argument.



## Squash an image



The resulting image will loose metadata, but it is handy to reduce image size:



    docker-companion squash my-awesome-image my-awesome-image-squashed



You can also make it pull before squashing it:



    docker-companion --pull squash my-awesome-image my-awesome-image-squashed:mytag



Or just squashing an image



    docker-companion squash my-awesome-image



to directly remove the intermediary (the source image, which will loose the tag)



    docker-companion squash --remove my-awesome-image



## Unpack an image



    docker-companion unpack my-awesome-image /my/path



The path must be absolute, and you must run it with root permission to keep file permissions.



You can squash the image right before unpacking it too:



    docker-companion --pull unpack --squash my-awesome-image /my/path



It can be handy sometimes to squash the image before unpacking it (very few cases where the latter fails)



You can supply also the --fatal global option to treat all warnings as fatal:



    docker-companion --fatal --pull unpack --squash my-awesome-image /my/path



## Get Latest release from github for amd64



```bash

curl -s https://api.github.com/repos/mudler/docker-companion/releases/latest \

| grep "browser_download_url.*amd64" \

| cut -d : -f 2,3 \

| tr -d \" \

| wget -i - -O docker-companion

```