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.
The simplest way is to download the latest release (for OSX and Linux) from https://github.com/elstak/klar/releases/ and put the binary in a folder in your PATH
(make sure it has execute permission).
Make sure you have Go language compiler installed and configured https://golang.org/doc/install
Then run
go get github.com/elstak/klar
make sure your Go binary folder is in your PATH
(e.g. export PATH=$PATH:/usr/local/go/bin
)
Klar process returns if 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 ofprotocol://host:port
-protocol
andport
default tohttp
and6060
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 areUnknown
,Negligible
,Low
,Medium
,High
,Critical
,Defcon1
. Default isUnknown
. -
CLAIR_THRESHOLD
- how many outputted vulnerabilities Klar can tolerate before returning1
. Default is0
. -
CLAIR_TIMEOUT
- timeout in minutes before Klar cancels the image scanning. Default is1
-
DOCKER_USER
- Docker registry account name. -
DOCKER_PASSWORD
- Docker registry account password. -
DOCKER_TOKEN
- Docker registry account token. (Can be used in place ofDOCKER_USER
andDOCKER_PASSWORD
) -
DOCKER_INSECURE
- Allow Klar to access registries with bad SSL certificates. Default isfalse
. Clair will need to be booted with-insecure-tls
for this to work. -
DOCKER_TIMEOUT
- timeout in minutes when trying to fetch layers from a docker registry -
DOCKER_PLATFORM_OS
- The operating system of the Docker image. Default islinux
. This only needs to be set if the image specified references a Docker ManifestList instead of a usual manifest. -
DOCKER_PLATFORM_ARCH
- The architecture the Docker image is optimized for. Default isamd64
. This only needs to be set if the image specified references a Docker ManifestList instead of a usual manifest. -
REGISTRY_INSECURE
- Allow Klar to access insecure registries (HTTP only). Default isfalse
. -
JSON_OUTPUT
- Output JSON, not plain text. Default isfalse
. -
FORMAT_OUTPUT
- Output format of the vulnerabilities. Supported formats arestandard
,json
,table
. Default isstandard
. IfJSON_OUTPUT
is set to true, this option is ignored. -
WHITELIST_FILE
- Path to the YAML file with the CVE whitelist. Look atwhitelist-example.yaml
for the file format. -
IGNORE_UNFIXED
- Do not count vulnerabilities without a fix towards the threshold
Usage:
CLAIR_ADDR=localhost CLAIR_OUTPUT=High CLAIR_THRESHOLD=10 DOCKER_USER=docker DOCKER_PASSWORD=secret klar postgres:9.5.1
You can enable more verbose output but setting KLAR_TRACE
to true.
- run
export KLAR_TRACE=true
to persist between runs.
Klar can be dockerized. Go to $GOPATH/src/github.com/elstak/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
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 ${REGISTRY}/my-image
For authentication against GCR (Google Cloud Registry), the easiest way is to use the application default credentials. These only work when running Klar from GCP. The only requirement is the Google Cloud SDK.
DOCKER_USER=oauth2accesstoken
DOCKER_PASSWORD="$(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)"