Klar

Integration of Clair and Docker Registry (supports both Clair API v1 and v3)

Klar is a simple tool to analyze images stored in a private or public Docker registry for security vulnerabilities using Clair https://github.com/coreos/clair. Klar is designed to be used as an integration tool so it relies on enviroment variables. It's a single binary which requires no dependencies.

Klar serves as a client which coordinates the image checks between the Docker registry and Clair.

Binary installation

The simplest way is to download the latest release (for OSX and Linux) from https://github.com/optiopay/klar/releases/ and put the binary in a folder in your PATH (make sure it has execute permission).

Installation from source code

Make sure you have Go language compiler installed and configured https://golang.org/doc/install

Then run

go get github.com/optiopay/klar

make sure your Go binary folder is in your PATH (e.g. export PATH=$PATH:/usr/local/go/bin)

Usage

Klar process returns 0 if the number of detected high severity vulnerabilities in an image is less than or equal to a threshold (see below) and 1 if there were more. It will return 2 if an error has prevented the image from being analyzed.

Klar can be configured via the following environment variables:

• CLAIR_ADDR - address of Clair server. It has a form of protocol://host:port - protocol and port default to http and 6060 respectively and may be omitted. You can also specify basic authentication in the URL: protocol://login:password@host:port.

• CLAIR_OUTPUT - severity level threshold, vulnerabilities with severity level higher than or equal to this threshold will be outputted. Supported levels are Unknown, Negligible, Low, Medium, High, Critical, . Default is .

Usage:

CLAIR_ADDR=localhost CLAIR_OUTPUT=High CLAIR_THRESHOLD=10 DOCKER_USER=docker DOCKER_PASSWORD=secret klar postgres:9.5.1

Debug Output

You can enable more verbose output but setting KLAR_TRACE to true.

• run export KLAR_TRACE=true to persist between runs.

Dockerized version

Klar can be dockerized. Go to $GOPATH/src/github.com/optiopay/klar and build Klar in project root. If you are on Linux:

CGO_ENABLED=0 go build -a -installsuffix cgo .

If you are on Mac don't forget to build it for Linux:

GOOS=linux go build .

To build Docker image run in the project root (replace klar with fully qualified name if you like):

docker build -t klar .

Then pass env vars as separate --env arguments, or create an env file and pass it as --env-file argument. For example save env vars as my-klar.env:

CLAIR_ADDR=localhost
CLAIR_OUTPUT=High
CLAIR_THRESHOLD=10
DOCKER_USER=docker
DOCKER_PASSWORD=secret

Then run

docker run --env-file=my-klar.env klar postgres:9.5.1

Amazon ECR support

There is no permanent username/password for Amazon ECR, the credentials must be retrived using aws ecr get-login and they are valid for 12 hours. Here is a sample script which may be used to provide Klar with ECR credentials:

DOCKER_LOGIN=`aws ecr get-login --no-include-email`
PASSWORD=`echo $DOCKER_LOGIN | cut -d' ' -f6`
REGISTRY=`echo $DOCKER_LOGIN | cut -d' ' -f7 | sed "s/https:\/\///"`
DOCKER_USER=AWS DOCKER_PASSWORD=${PASSWORD} ./klar ${REGISTRY}/my-image

Google GCR support

For authentication against GCR (Google Cloud Registry), the easiest way is to use the application default credentials. These only work when running Klar from GCP. The only requirement is the Google Cloud SDK.

DOCKER_USER=oauth2accesstoken
DOCKER_PASSWORD="$(gcloud auth application-default print-access-token)"

With Docker:

DOCKER_USER=oauth2accesstoken
DOCKER_PASSWORD="$(docker run --rm google/cloud-sdk:alpine gcloud auth application-default print-access-token)"