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* inject a script for initFranck Cuny2021-04-221-0/+43
| | | | | | | | | Once we will be ready to boot our VM, we will need an init script in place. For this, we create a simple shell script which we populate using the environment variables and command extracted from the container. The init script is stored in /init.sh within the new image, and we will configure the boot parameter to find it there.
* extract layers to a mounted loop deviceFranck Cuny2021-04-221-1/+119
| | | | | | | | | | | | | We create a loop device by pre-allocating space to a file on disk. This file is then converted to an ext4 partition, which we mount to a temporary path on the host. Once this is done, we extract all the layers from the given container on that mounted path. We also add a few extra files to the image (`/etc/hosts` and `/etc/resolv.conf`). When we're done extracting and writing, we run resize2fs in order to resize the image to a more reasonable size.
* add a lease to the Go contextFranck Cuny2021-04-151-0/+6
| | | | | | | | | | | | This will ensure that our container will not be deleted while we work on it. In addition, a default expiry of 24 hours will be set on it once the lease is released (once the program is completed). See [1] for more details. [1] https://github.com/containerd/containerd/blob/261c107ffc4ff681bc73988f64e3f60c32233b37/docs/garbage-collection.md Signed-off-by: Franck Cuny <franck@fcuny.net>
* pull a container into a namespaceFranck Cuny2021-04-131-0/+56
Pull an image provided as an argument to the program. We're only interested in images for Linux/amd64 at the moment. We setup a default namespace for containerd named `c2vm`. Images that will be pulled by containerd will be stored inside that namespace. Once the program is build it can be run like this: ``` ; sudo ./c2vm -container docker.io/library/redis:latest pulled docker.io/library/redis:latest (38667897 bytes) ``` And the image is indeed in the namespace: ``` ; sudo ctr -n c2vm images ls -q docker.io/library/redis:latest ```