Please be aware skopeo is still work in progress and it currently supports only registry API V2
skopeo is a command line utility for various operations on container images and image repositories.
skopeo is able to inspect a repository on a Docker registry and fetch images layers.
By inspect I mean it fetches the repository's manifest and it is able to show you a docker inspect-like
json output about a whole repository or a tag. This tool, in contrast to docker inspect, helps you gather useful information about
a repository or a tag before pulling it (using disk space) - e.g. - which tags are available for the given repository? which labels the image has?
Examples:
# show properties of fedora:latest
$ skopeo inspect docker://docker.io/fedora
{
"Name": "docker.io/library/fedora",
"Tag": "latest",
"Digest": "sha256:cfd8f071bf8da7a466748f522406f7ae5908d002af1b1a1c0dcf893e183e5b32",
"RepoTags": [
"20",
"21",
"22",
"23",
"heisenbug",
"latest",
"rawhide"
],
"Created": "2016-03-04T18:40:02.92155334Z",
"DockerVersion": "1.9.1",
"Labels": {},
"Architecture": "amd64",
"Os": "linux",
"Layers": [
"sha256:236608c7b546e2f4e7223526c74fc71470ba06d46ec82aeb402e704bfdee02a2",
"sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"
]
}
# show unverifed image's digest
$ skopeo inspect docker://docker.io/fedora:rawhide | jq '.Digest'
"sha256:905b4846938c8aef94f52f3e41a11398ae5b40f5855fb0e40ed9c157e721d7f8"skopeo can copy container images between various storage mechanisms,
e.g. Docker registries (including the Docker Hub), the Atomic Registry,
local directories, and local OCI-layout directories:
$ skopeo copy docker://busybox:1-glibc atomic:myns/unsigned:streaming
$ skopeo copy docker://busybox:latest dir:existingemptydirectory
$ skopeo copy docker://busybox:latest oci:busybox_ocilayoutFor example,
$ skopeo delete docker://localhost:5000/imagename:latestWhen interacting with private registries, skopeo first looks for --creds (for skopeo inspect|delete) or --src-creds|--dest-creds (for skopeo copy) flags. If those aren't provided, it looks for the Docker's cli config file (usually located at $HOME/.docker/config.json) to get the credentials needed to authenticate. The ultimate fallback, as Docker does, is to provide an empty authentication when interacting with those registries.
Examples:
$ cat /home/runcom/.docker/config.json
{
"auths": {
"myregistrydomain.com:5000": {
"auth": "dGVzdHVzZXI6dGVzdHBhc3N3b3Jk",
"email": "[email protected]"
}
}
}
# we can see I'm already authenticated via docker login so everything will be fine
$ skopeo inspect docker://myregistrydomain.com:5000/busybox
{"Tag":"latest","Digest":"sha256:473bb2189d7b913ed7187a33d11e743fdc2f88931122a44d91a301b64419f092","RepoTags":["latest"],"Comment":"","Created":"2016-01-15T18:06:41.282540103Z","ContainerConfig":{"Hostname":"aded96b43f48","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":["/bin/sh","-c","#(nop) CMD [\"sh\"]"],"Image":"9e77fef7a1c9f989988c06620dabc4020c607885b959a2cbd7c2283c91da3e33","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"DockerVersion":"1.8.3","Author":"","Config":{"Hostname":"aded96b43f48","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":["sh"],"Image":"9e77fef7a1c9f989988c06620dabc4020c607885b959a2cbd7c2283c91da3e33","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"Architecture":"amd64","Os":"linux"}
# let's try now to fake a non existent Docker's config file
$ cat /home/runcom/.docker/config.json
{}
$ skopeo inspect docker://myregistrydomain.com:5000/busybox
FATA[0000] unauthorized: authentication required
# passing --creds - we can see that everything goes fine
$ skopeo inspect --creds=testuser:testpassword docker://myregistrydomain.com:5000/busybox
{"Tag":"latest","Digest":"sha256:473bb2189d7b913ed7187a33d11e743fdc2f88931122a44d91a301b64419f092","RepoTags":["latest"],"Comment":"","Created":"2016-01-15T18:06:41.282540103Z","ContainerConfig":{"Hostname":"aded96b43f48","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":["/bin/sh","-c","#(nop) CMD [\"sh\"]"],"Image":"9e77fef7a1c9f989988c06620dabc4020c607885b959a2cbd7c2283c91da3e33","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"DockerVersion":"1.8.3","Author":"","Config":{"Hostname":"aded96b43f48","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":null,"Cmd":["sh"],"Image":"9e77fef7a1c9f989988c06620dabc4020c607885b959a2cbd7c2283c91da3e33","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"Architecture":"amd64","Os":"linux"}
# skopeo copy example:
$ skopeo copy --src-creds=testuser:testpassword docker://myregistrydomain.com:5000/private oci:local_oci_imageIf your cli config is found but it doesn't contain the necessary credentials for the queried registry
you'll get an error. You can fix this by either logging in (via docker login) or providing --creds or --src-creds|--dest-creds.
To build the manual you will need go-md2man.
$ sudo apt-get install go-md2manTo build the skopeo binary you need at least Go 1.5 because it uses the latest GO15VENDOREXPERIMENT flag. Also, make sure to clone the repository in your GOPATH - otherwise compilation fails.
$ git clone https://github.com/projectatomic/skopeo $GOPATH/src/github.com/projectatomic/skopeo
$ cd $GOPATH/src/github.com/projectatomic/skopeo && make allTo build localy on OSX:
$ brew install gpgme
$ make binary-localYou may need to install additional development packages: gpgme-devel and libassuan-devel
$ dnf install gpgme-devel libassuan-develIf you built from source:
$ sudo make installskopeo is also available from Fedora 23:
sudo dnf install skopeo- list all images on registry?
- registry v2 search?
- support output to docker load tar(s)
- show repo tags via flag or when reference isn't tagged or digested
- add tests (integration with deployed registries in container - Docker-like)
- support rkt/appc image spec
- provide a format flag - just use the awesome jq
skopeo uses a custom bash script for dependencies management. This script is located at hack/vendor.sh.
In order to add a new dependency to this project:
- add a new line to
hack/vendor.sh(e.g.clone git github.com/pkg/errors master) - run
hack/vendor.sh
In order to update an existing dependency (or more):
- update the relevant dependency line in
hack/vendor.sh - run
hack/vendor.sh
In order to test out new PRs from containers/image to not break skopeo:
- update
hack/vendor.sh. Find out thecontainers/imagedependency; update it to vendor from your own branch and your own repository fork (e.g.clone git github.com/containers/image my-branch https://github.com/runcom/image) - run
hack/vendor.sh
skopeo is licensed under the Apache License, Version 2.0. See LICENSE for the full license text.