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goodwithtech/dockle

By goodwithtech

•Updated over 1 year ago

Image
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1M+

goodwithtech/dockle repository overview

Financial Contributors on Open Collective GitHub release CircleCI Go Report Card License: AGPL v3

Dockle - Container Image Linter for Security, Helping build the Best-Practice Docker Image, Easy to start

Dockle helps you:

  1. Build Best Practice⁠ Docker images
  2. Build secure Docker images
$ brew untap goodwithtech/dockle # who use 0.1.16 or older version
$ brew install goodwithtech/r/dockle
$ dockle [YOUR_IMAGE_NAME]

See Installation⁠ and Common Examples⁠

⁠Checkpoints Comparison

⁠TOC

⁠Features

  • Detect container's vulnerabilities
  • Helping build best-practice Dockerfile
  • Simple usage
  • CIS Benchmarks Support
    • High accuracy
  • DevSecOps
    • Suitable for CI such as Travis CI, CircleCI, Jenkins, etc.
    • See CI Example⁠

⁠Comparison

 Dockle⁠Hadolint⁠Docker Bench for Security⁠Clair⁠
TargetImageDockerfileHost
Docker Daemon
Image
Container Runtime
Image
How to runBinaryBinaryShellScriptBinary
DependencyNoNoSome dependenciesNo
CI Suitable✓✓xx
PurposeSecurity Audit
Dockerfile Lint
Dockerfile LintSecurity Audit
Dockerfile Lint
Scan Vulnerabilities

⁠Installation

⁠Homebrew (Mac OS X / Linux and WSL)

You can use Homebrew on Mac OS X⁠ or Linux and WSL (Windows Subsystem for Linux)⁠.

$ brew install goodwithtech/r/dockle

⁠RHEL/CentOS

$ VERSION=$(
 curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
 grep '"tag_name":' | \
 sed -E 's/.*"v([^"]+)".*/\1/' \
) && rpm -ivh https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Linux-64bit.rpm

⁠Debian/Ubuntu

$ VERSION=$(
 curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
 grep '"tag_name":' | \
 sed -E 's/.*"v([^"]+)".*/\1/' \
) && curl -L -o dockle.deb https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Linux-64bit.deb
$ sudo dpkg -i dockle.deb && rm dockle.deb

⁠Arch Linux

dockle-bin can be installed from the Arch User Repository. Examples:

pikaur -Sy dockle-bin

or

yay -Sy dockle-bin

⁠Windows

$ VERSION=$(
 curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
 grep '"tag_name":' | \
 sed -E 's/.*"v([^"]+)".*/\1/' \
) && curl -L -o dockle.zip https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Windows-64bit.zip
$ unzip dockle.zip && rm dockle.zip
$ ./dockle.exe [IMAGE_NAME]

⁠Binary

You can get the latest version binary from releases page⁠.

Download the archive file for your operating system/architecture. Unpack the archive, and put the binary somewhere in your $PATH (on UNIX-y systems, /usr/local/bin or the like).

  • NOTE: Make sure that it's execution bits turned on. (chmod +x dockle)

⁠From source

$ GO111MODULE=off go get github.com/goodwithtech/dockle/cmd/dockle
$ cd $GOPATH/src/github.com/goodwithtech/dockle && GO111MODULE=on go build -o $GOPATH/bin/dockle cmd/dockle/main.go

⁠Use Docker

There's a Dockle image on Docker Hub⁠ also. You can try dockle before installing the command.

$ VERSION=$(
 curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
 grep '"tag_name":' | \
 sed -E 's/.*"v([^"]+)".*/\1/' \
) && docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  goodwithtech/dockle:v${VERSION} [YOUR_IMAGE_NAME]

You only need -v /var/run/docker.sock:/var/run/docker.sock when you'd like to scan the image on your host machine.

⁠Quick Start

⁠Basic

Simply specify an image name (and a tag).

$ dockle [YOUR_IMAGE_NAME]
Result
FATAL   - CIS-DI-0009: Use COPY instead of ADD in Dockerfile
        * Use COPY : /bin/sh -c #(nop) ADD file:81c0a803075715d1a6b4f75a29f8a01b21cc170cfc1bff6702317d1be2fe71a3 in /app/credentials.json
FATAL   - CIS-DI-0010: Do not store credential in ENVIRONMENT vars/files
        * Suspicious filename found : app/credentials.json
FATAL   - DKL-DI-0005: Clear apt-get caches
        * Use 'rm -rf /var/lib/apt/lists' after 'apt-get install' : /bin/sh -c apt-get update && apt-get install -y git
FATAL   - DKL-LI-0001: Avoid empty password
        * No password user found! username : nopasswd
WARN    - CIS-DI-0001: Create a user for the container
        * Last user should not be root
INFO    - CIS-DI-0005: Enable Content trust for Docker
        * export DOCKER_CONTENT_TRUST=1 before docker pull/build
INFO    - CIS-DI-0008: Confirm safety of setuid/setgid files
        * setuid file: app/suid.txt urw-r--r--
        * setgid file: app/gid.txt grw-r--r--
        * setuid file: usr/bin/gpasswd urwxr-xr-x
        * setgid file: usr/bin/wall grwxr-xr-x
        * setuid file: bin/su urwxr-xr-x
        * setuid file: bin/umount urwxr-xr-x
        * setuid file: bin/mount urwxr-xr-x
        * setgid file: usr/bin/ssh-agent grwxr-xr-x
        * setuid file: etc/shadow urw-r-----
        * setuid file: usr/bin/chsh urwxr-xr-x
        * setuid file: usr/bin/chfn urwxr-xr-x
        * setuid file: usr/lib/openssh/ssh-keysign urwxr-xr-x
        * setgid file: etc/passwd grw-r--r--
        * setgid file: sbin/unix_chkpwd grwxr-xr-x
        * setgid file: usr/bin/chage grwxr-xr-x
        * setuid file: usr/bin/passwd urwxr-xr-x
        * setgid file: usr/bin/expiry grwxr-xr-x
        * setuid file: usr/bin/newgrp urwxr-xr-x
IGNORE  - CIS-DI-0006: Add HEALTHCHECK instruction to the container image

⁠Docker

Also, you can use Docker to use dockle command as follow.

$ export DOCKLE_LATEST=$(
 curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
 grep '"tag_name":' | \
 sed -E 's/.*"v([^"]+)".*/\1/' \
)
$ docker run --rm goodwithtech/dockle:v${DOCKLE_LATEST} [YOUR_IMAGE_NAME]
  • If you'd like to scan the image on your host machine, you need to mount docker.sock.

    $ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock ...
    

⁠Checkpoint Summary

CODEDESCRIPTIONLEVEL※⁠
CIS's Docker Image Checkpoints⁠
CIS-DI-0001⁠Create a user for the containerWARN
CIS-DI-0002⁠Use trusted base images for containersFATAL
CIS-DI-0003⁠Do not install unnecessary packages in the containerFATAL
CIS-DI-0004⁠Scan and rebuild the images to include security patchesFATAL
CIS-DI-0005⁠Enable Content trust for DockerINFO
CIS-DI-0006⁠Add HEALTHCHECK instruction to the container imageWARN
CIS-DI-0007⁠Do not use update instructions alone in the DockerfileFATAL
CIS-DI-0008⁠Confirm safety of setuid and setgid filesINFO
CIS-DI-0009⁠Use COPY instead of ADD in DockerfileFATAL
CIS-DI-0010⁠Do not store secrets in DockerfilesFATAL
CIS-DI-0011⁠Install verified packages onlyINFO
Dockle Checkpoints for Docker⁠
DKL-DI-0001⁠Avoid sudo commandFATAL
DKL-DI-0002⁠Avoid sensitive directory mountingFATAL
DKL-DI-0003⁠Avoid apt-get upgrade, apk upgrade, dist-upgradeFATAL
DKL-DI-0004⁠Use apk add with --no-cacheFATAL
DKL-DI-0005⁠Clear apt-get cachesFATAL
DKL-DI-0006⁠Avoid latest tagWARN
Dockle Checkpoints for Linux⁠
DKL-LI-0001⁠Avoid empty passwordFATAL
DKL-LI-0002⁠Be unique UID/GROUPsFATAL
DKL-LI-0003⁠Only put necessary filesINFO

⁠Level

Dockle has 5 check levels.

LEVELDESCRIPTION
FATALBe practical and prudent
WARNBe practical and prudent, but limited uses (even if official images)
INFOMay negatively inhibit the utility or performance
SKIPNot found target files
PASSNot found any problems

⁠Common Examples

⁠Scan an image

Simply specify an image name (and a tag).

$ dockle goodwithtech/test-image:v1
Result
FATAL   - CIS-DI-0001: Create a user for the container
        * Last user should not be root
WARN    - CIS-DI-0005: Enable Content trust for Docker
        * export DOCKER_CONTENT_TRUST=1 before docker pull/build
FATAL   - CIS-DI-0006: Add HEALTHCHECK instruction to the container image
        * not found HEALTHCHECK statement
FATAL   - CIS-DI-0007: Do not use update instructions alone in the Dockerfile
        * Use 'Always combine RUN 'apt-get update' with 'apt-get install' : /bin/sh -c apt-get update && apt-get install -y git
FATAL   - CIS-DI-0008: Remove setuid and setgid permissions in the images
        * Found setuid file: etc/passwd grw-r--r--
        * Found setuid file: usr/lib/openssh/ssh-keysign urwxr-xr-x
        * Found setuid file: app/hoge.txt ugrw-r--r--
        * Found setuid file: app/hoge.txt ugrw-r--r--
        * Found setuid file: etc/shadow urw-r-----
FATAL   - CIS-DI-0009: Use COPY instead of ADD in Dockerfile
        * Use COPY : /bin/sh -c #(nop) ADD file:81c0a803075715d1a6b4f75a29f8a01b21cc170cfc1bff6702317d1be2fe71a3 in /app/credentials.json
FATAL   - CIS-DI-0010: Do not store secrets in ENVIRONMENT variables
        * Suspicious ENV key found : MYSQL_PASSWD
FATAL   - CIS-DI-0010: Do not store secret files
        * Suspicious filename found : app/credentials.json
PASS    - DKL-DI-0001: Avoid sudo command
FATAL   - DKL-DI-0002: Avoid sensitive directory mounting
        * Avoid mounting sensitive dirs : /usr
PASS    - DKL-DI-0003: Avoid apt-get/apk/dist-upgrade
PASS    - DKL-DI-0004: Use apk add with --no-cache
FATAL   - DKL-DI-0005: Clear apt-get caches
        * Use 'apt-get clean && rm -rf /var/lib/apt/lists/*' : /bin/sh -c apt-get update && apt-get install -y git
PASS    - DKL-DI-0006: Avoid latest tag
FATAL   - DKL-LI-0001: Avoid empty password
        * No password user found! username : nopasswd
PASS    - DKL-LI-0002: Be unique UID
PASS    - DKL-LI-0002: Be unique GROUP
⁠Scan an image file
$ docker save alpine:latest -o alpine.tar
$ dockle --input alpine.tar
⁠Get or Save the results as JSON
$ dockle -f json goodwithtech/test-image:v1
$ dockle -f json -o results.json goodwithtech/test-image:v1
Result
{
  "summary": {
    "fatal": 6,
    "warn": 2,
    "info": 2,
    "pass": 7
  },
  "details": [
    {
      "code": "CIS-DI-0001",
      "title": "Create a user for the container",
      "level": "WARN",
      "alerts": [
        "Last user should not be root"
      ]
    },
    {
      "code": "CIS-DI-0005",
      "title": "Enable Content trust for Docker",
      "level": "INFO",
      "alerts": [
        "export DOCKER_CONTENT_TRUST=1 before docker pull/build"
      ]
    },
    {
      "code": "CIS-DI-0006",
      "title": "Add HEALTHCHECK instruction to the container image",
      "level": "WARN",
      "alerts": [
        "not found HEALTHCHECK statement"
      ]
    },
    {
      "code": "CIS-DI-0008",
      "title": "Remove setuid and setgid permissions in the images",
      "level": "INFO",
      "alerts": [
        "Found setuid file: usr/lib/openssh/ssh-keysign urwxr-xr-x"
      ]
    },
    {
      "code": "CIS-DI-0009",
      "title": "Use COPY instead of ADD in Dockerfile",
      "level": "FATAL",
      "alerts": [
        "Use COPY : /bin/sh -c #(nop) ADD file:81c0a803075715d1a6b4f75a29f8a01b21cc170cfc1bff6702317d1be2fe71a3 in /app/credentials.json "
      ]
    },
    {
      "code": "CIS-DI-0010",
      "title": "Do not store secrets in ENVIRONMENT variables",
      "level": "FATAL",
      "alerts": [
        "Suspicious ENV key found : MYSQL_PASSWD"
      ]
    },
    {
      "code": "CIS-DI-0010",
      "title": "Do not store secret files",
      "level": "FATAL",
      "alerts": [
        "Suspicious filename found : app/credentials.json "
      ]
    },
    {
      "code": "DKL-DI-0002",
      "title": "Avoid sensitive directory mounting",
      "level": "FATAL",
      "alerts": [
        "Avoid mounting sensitive dirs : /usr"
      ]
    },
    {
      "code": "DKL-DI-0005",
      "title": "Clear apt-get caches",
      "level": "FATAL",
      "alerts": [
        "Use 'rm -rf /var/lib/apt/lists' after 'apt-get install' : /bin/sh -c apt-get update \u0026\u0026 apt-get install -y git"
      ]
    },
    {
      "code": "DKL-LI-0001",
      "title": "Avoid empty password",
      "level": "FATAL",
      "alerts": [
        "No password user found! username : nopasswd"
      ]
    }
  ]
}
⁠Specify exit code

By default, Dockle exits with code 0 even if there are some problems.

Use the --exit-code, -c option to exit with a non-zero exit code if WARN or FATAL alert were found.

$ dockle --exit-code 1 [IMAGE_NAME]
⁠Specify exit level

By default, --exit-code run when there are WARN or FATAL level alerts.

Use the --exit-level, -l option to change alert level. You can set info, warn or fatal.

$ dockle --exit-code 1 --exit-level info [IMAGE_NAME]
$ dockle --exit-code 1 --exit-level fatal [IMAGE_NAME]
⁠Ignore the specified checkpoints

The --ignore, -i option can ignore specified checkpoints.

$ dockle -i CIS-DI-0001 -i DKL-DI-0006 [IMAGE_NAME]

Or, use .dockleignore file.

$ cat .dockleignore
# set root to default user because we want to run nginx
CIS-DI-0001
# Use latest tag because to check the image inside only
DKL-DI-0006

⁠Continuous Integration (CI)

You can scan your built image with Dockle in Travis CI/CircleCI.

In these examples, the test will fail with if any warnings were found.

Though, you can ignore the specified target checkpoints by using .dockleignore file.

Or, if you just want the results to display and not let the test fail for this, specify --exit-code to 0 in dockle command.

⁠Travis CI
.travis.yml
services:
  - docker

env:
  global:
    - COMMIT=${TRAVIS_COMMIT::8}

before_install:
  - docker build -t dockle-ci-test:${COMMIT} .
  - export VERSION=$(curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | grep '"tag_name":' | sed -E 's/.*"v([^"]+)".*/\1/')
  - wget https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Linux-64bit.tar.gz
  - tar zxvf dockle_${VERSION}_Linux-64bit.tar.gz
script:
  - ./dockle dockle-ci-test:${COMMIT}
  - ./dockle --exit-code 1 dockle-ci-test:${COMMIT}
⁠CircleCI
.circleci/config.yml
jobs:
  build:
    docker:
      - image: docker:18.09-git
    steps:
      - checkout
      - setup_remote_docker
      - run:
          name: Build image
          command: docker build -t dockle-ci-test:${CIRCLE_SHA1} .
      - run:
          name: Install dockle
          command: |
            apk add --update curl
            VERSION=$(
                curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
                grep '"tag_name":' | \
                sed -E 's/.*"v([^"]+)".*/\1/'
            )
            wget https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Linux-64bit.tar.gz
            tar zxvf dockle_${VERSION}_Linux-64bit.tar.gz
            mv dockle /usr/local/bin
      - run:
          name: Scan the local image with dockle
          command: dockle --exit-code 1 dockle-ci-test:${CIRCLE_SHA1}
workflows:
  version: 2
  release:
    jobs:
      - build

⁠GitLab CI

.gitlab-ci.yml
image: docker:stable
stages:
  - test

variables:
  DOCKER_HOST: tcp://docker:2375/
  DOCKER_DRIVER: overlay2
services:
  - docker:dind

unit_test:
  stage: test
  before_script:
    - apk -Uuv add bash git curl tar sed grep
  script:
    - docker build -t dockle-ci-test:${CI_COMMIT_SHORT_SHA} .
    - |
      VERSION=$(
      curl --silent "https://api.github.com/repos/goodwithtech/dockle/releases/latest" | \
      grep '"tag_name":' | \
      sed -E 's/.*"v([^"]+)".*/\1/' \
      ) && curl -L -o dockle.tar.gz https://github.com/goodwithtech/dockle/releases/download/v${VERSION}/dockle_${VERSION}_Linux-64bit.tar.gz &&  \
      tar zxvf dockle.tar.gz
    - ./dockle --exit-code 1 dockle-ci-test:${CI_COMMIT_SHORT_SHA}

⁠Authorization for Private Docker Registry

Dockle can download images from a private registry, without installing Docker or any other 3rd party tools. It's designed so for ease of use in a CI process.

All you have to do is: install Dockle and set ENVIRONMENT variables.

  • NOTE: I don't recommend using ENV vars in your local machine.
⁠Docker Hub

To download the private repository from Docker Hub, you need to set DOCKLE_AUTH_URL, DOCKLE_USERNAME and DOCKLE_PASSWORD ENV vars.

export DOCKLE_AUTH_URL=https://registry.hub.docker.com
export DOCKLE_USERNAME={DOCKERHUB_USERNAME}
export DOCKLE_PASSWORD={DOCKERHUB_PASSWORD}
  • NOTE: You don't need to set ENV vars when downloading from the public repository.
⁠Amazon ECR (Elastic Container Registry)

Dockle uses the AWS SDK. You don't need to install aws CLI tool.

Use AWS CLI's ENVIRONMENT variables⁠.

export AWS_ACCESS_KEY_ID={AWS ACCESS KEY}
export AWS_SECRET_ACCESS_KEY={SECRET KEY}
export AWS_DEFAULT_REGION={AWS REGION}
⁠GCR (Google Container Registry)

Dockle uses the Google Cloud SDK. So, you don't need to install gcloud command.

If you'd like to use the target project's repository, you can settle via GOOGLE_APPLICATION_CREDENTIAL.

# must set DOCKLE_USERNAME empty char
export GOOGLE_APPLICATION_CREDENTIALS=/path/to/credential.json
⁠Self Hosted Registry (BasicAuth)

BasicAuth server needs DOCKLE_USERNAME and DOCKLE_PASSWORD.

export DOCKLE_USERNAME={USERNAME}
export DOCKLE_PASSWORD={PASSWORD}

# if you'd like to use 80 port, use NonSSL
export DOCKLE_NON_SSL=true

⁠Credits

Special Thanks to @knqyf263⁠ (Teppei Fukuda) and Trivy⁠

⁠Contributors

⁠Code Contributors

This project exists thanks to all the people who contribute. [Contribute⁠].

⁠Financial Contributors

Become a financial contributor and help us sustain our community. [Contribute⁠]

⁠Individuals

⁠Organizations

Support this project with your organization. Your logo will show up here with a link to your website. [Contribute⁠]

⁠License

  • AGPLv3

⁠Author

@tomoyamachi⁠ (Tomoya Amachi)

⁠Roadmap

  • JSON output
  • Check php.ini file
  • Check nginx.conf file
  • create CI badges
  • Check /etc/hosts
    • duplicates
    • hostname
    • localhost
  • Packages
    • Package managers
  • File Permissions
    • Insecure permission
  • Image Size
    • check large size container

⁠if running docker daemon...

  • Networking
    • docker port container if docker running
    • by file
      • /proc/1/net/tcp : openning port (if running)
  • Volume mount
    • dangerous mount
      • /boot, /dev, /etc, /lib

Tag summary

Content type

Image

Digest

sha256:eade932f7…

Size

10.7 MB

Last updated

over 1 year ago

docker pull goodwithtech/dockle