THE PROJECT HAS BEEN MOVED TO projectatomic/skopeo
Please be aware skopeo is still work in progress
skopeo is a command line utility which is able to inspect a repository on a Docker registry.
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 repository's labels of rhel7:latest
$ skopeo registry.access.redhat.com/rhel7 | jq '.Config.Labels'
{
"Architecture": "x86_64",
"Authoritative_Registry": "registry.access.redhat.com",
"BZComponent": "rhel-server-docker",
"Build_Host": "rcm-img04.build.eng.bos.redhat.com",
"Name": "rhel7/rhel",
"Release": "38",
"Vendor": "Red Hat, Inc.",
"Version": "7.2"
}
# show repository's tags
$ skopeo docker.io/fedora | jq '.RepoTags'
[
"20",
"21",
"22",
"23",
"heisenbug",
"latest",
"rawhide"
]
# show image's digest
$ skopeo docker.io/fedora:rawhide | jq '.Digest'
"sha256:905b4846938c8aef94f52f3e41a11398ae5b40f5855fb0e40ed9c157e721d7f8"When interacting with private registries, skopeo first looks for the Docker's cli config file (usually located at $HOME/.docker/config.json) to get the credentials needed to authenticate. When the file isn't available it falls back looking for --username and --password flags. The ultimate fallback, as Docker does, is to provide an empty authentication when interacting with those registries.
Examples:
# on my system
$ skopeo --help | grep docker-cfg
--docker-cfg "/home/runcom/.docker" Docker's cli config for auth
$ cat /home/runcom/.docker/config.json
{
"auths": {
"myregistrydomain.com:5000": {
"auth": "dGVzdHVzZXI6dGVzdHBhc3N3b3Jk",
"email": "stuf@ex.cm"
}
}
}
# we can see I'm already authenticated via docker login so everything will be fine
$ skopeo 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
$ skopeo --docker-cfg="" myregistrydomain.com:5000/busybox
FATA[0000] Get https://myregistrydomain.com:5000/v2/busybox/manifests/latest: no basic auth credentials
# passing --username and --password - we can see that everything goes fine
$ skopeo --docker-cfg="" --username=testuser --password=testpassword 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"}If 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 --username
and --password.
Building
To build skopeo 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.
$ cd $GOPATH/src
$ mkdir -p github.com/runcom
$ cd runcom
$ git clone https://github.com/runcom/skopeo
$ cd skopeo && make binaryTo build the man page you need go-md2man available on your system, then:
$ make man
If you built from source:
$ sudo make installskopeo is also available from Fedora 23:
sudo dnf install skopeoYou need Docker installed on your system in order to run the test suite
$ make test-integration- make skopeo docker registry v2 only
- output raw manifest
- download layers and support docker load tar(s)
- get rid of docker/docker code (?)
- 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
ASL 2.0