zot

zot is a vendor-neutral OCI image repository server purely based on OCI Distribution Specification.

• Conforms to OCI distribution spec APIs
• Uses OCI storage layout for storage layout
• Supports helm charts
• Currently suitable for on-prem deployments (e.g. colocated with Kubernetes)
• Vulnerability scanning of images
• Command-line client support
• TLS support
• Authentication via:
  • TLS mutual authentication
  • HTTP Basic (local htpasswd and LDAP)
  • HTTP Bearer token
• Doesn't require root privileges
• Storage optimizations:
  • Automatic garbage collection of orphaned blobs
  • Layer deduplication using hard links when content is identical
• Swagger based documentation
• Released under Apache 2.0 License
• go get -u github.com/anuvu/zot/cmd/zot

Presentations

• OCI Weekly Discussion - Oct 2, 2019

Build and install binary (using host's toolchain)

go get -u github.com/anuvu/zot/cmd/zot

Full CI/CD Build

• Build inside a container (preferred)

make binary-container

• Alternatively, build inside a container using stacker (preferred)

make binary-stacker

• Build using host's toolchain

make

Build artifacts are in bin/

Serving

bin/zot serve _config-file_

Examples of config files are available in examples/ dir.

Container Image

The Dockerfile in this repo can be used to build a container image that runs zot.

To build the image with ref zot:latest:

make image

Then run the image with your preferred container runtime:

# with podman
podman run --rm -it -p 5000:5000 -v $(pwd)/registry:/var/lib/registry zot:latest

# with docker
docker run --rm -it -p 5000:5000 -v $(pwd)/registry:/var/lib/registry zot:latest

This will run a registry at http://localhost:5000, storing content at ./registry (bind mounted to /var/lib/registry in the container). By default, auth is disabled.

If you wish use custom configuration settings, you can override the YAML config file located at /etc/zot/config.yml:

# Example: using a local file "custom-config.yml" that
# listens on port 8080 and uses /tmp/zot for storage root
podman run --rm -p 8080:8080 \
  -v $(pwd)/custom-config.yml:/etc/zot/config.yml \
  -v $(pwd)/registry:/tmp/zot \
  zot:latest

CLI

The same zot binary can be used for interacting with any zot server instances.

Adding a zot server URL

To add a zot server URL with an alias "remote-zot":

$ zot config add remote-zot https://server-example:8080

List all configured URLs with their aliases:

$ zot config -l
remote-zot https://server-example:8080
local      http://localhost:8080

Listing images

You can list all images from a server by using its alias specified in this step:

$ zot images remote-zot
IMAGE NAME                        TAG                       DIGEST    SIZE
postgres                          9.6.18-alpine             ef27f3e1  14.4MB
postgres                          9.5-alpine                264450a7  14.4MB
busybox                           latest                    414aeb86  707.8KB

Or filter the list by an image name:

$ zot images remote-zot -n busybox
IMAGE NAME                        TAG                       DIGEST    SIZE
busybox                           latest                    414aeb86  707.8KB

Scanning images for known vulnerabilities

You can fetch CVE (Common Vulnerabilities and Exposures) info for images hosted on zot

• Get all images affected by a CVE

$ zot cve remote-zot -i CVE-2017-9935
IMAGE NAME                        TAG                       DIGEST    SIZE
c3/openjdk-dev                    commit-5be4d92            ac3762e2  335MB

• Get all CVEs for an image

$ zot cve remote-zot -I c3/openjdk-dev:0.3.19
ID                SEVERITY  TITLE
CVE-2015-8540     LOW       libpng: underflow read in png_check_keyword()
CVE-2017-16826    LOW       binutils: Invalid memory access in the coff_s...

• Get detailed json output

$ zot cve remote-zot -I c3/openjdk-dev:0.3.19 -o json
{
  "Tag": "0.3.19",
  "CVEList": [
    {
      "Id": "CVE-2019-17006",
      "Severity": "MEDIUM",
      "Title": "nss: Check length of inputs for cryptographic primitives",
      "Description": "A vulnerability was discovered in nss where input text length was not checked when using certain cryptographic primitives. This could lead to a heap-buffer overflow resulting in a crash and data leak. The highest threat is to confidentiality and integrity of data as well as system availability.",
      "PackageList": [
        {
          "Name": "nss",
          "InstalledVersion": "3.44.0-7.el7_7",
          "FixedVersion": "Not Specified"
        },
        {
          "Name": "nss-sysinit",
          "InstalledVersion": "3.44.0-7.el7_7",
          "FixedVersion": "Not Specified"
        },
        {
          "Name": "nss-tools",
          "InstalledVersion": "3.44.0-7.el7_7",
          "FixedVersion": "Not Specified"
        }
      ]
    },

• Get all images in a specific repo affected by a CVE

$ zot cve remote-zot -I c3/openjdk-dev -i CVE-2017-9935
IMAGE NAME                        TAG                       DIGEST    SIZE
c3/openjdk-dev                    commit-2674e8a            71046748  338MB
c3/openjdk-dev                    commit-bd5cc94            0ab7fc76  

• Get all images of a specific repo where a CVE is fixed

$ zot cve remote-zot -I c3/openjdk-dev -i CVE-2017-9935 --fixed
IMAGE NAME                        TAG                       DIGEST    SIZE
c3/openjdk-dev                    commit-2674e8a-squashfs   b545b8ba  321MB
c3/openjdk-dev                    commit-d5024ec-squashfs   cd45f8cf  321MB

Ecosystem

Since we couldn't find clients or client libraries that are stictly compliant to the dist spec, we had to patch containers/image (available as anuvu/image) and then link various binaries against the patched version.

skopeo

skopeo is a tool to work with remote image repositories.

We have a patched version available that works with zot.

git clone https://github.com/anuvu/skopeo

cd skopeo

make GO111MODULE=on binary-local

cri-o

cri-o is a OCI-based Kubernetes container runtime interface.

We have a patched version of containers/image available that works with zot which must be linked with cri-o.

git clone https://github.com/cri-o/cri-o

cd cri-o

echo 'replace github.com/containers/image => github.com/anuvu/image v1.5.2-0.20190827234748-f71edca6153a' >> go.mod

make bin/crio crio.conf GO111MODULE=on

Caveats

• go 1.12+
• The OCI distribution spec is still WIP, and we try to keep up