docker registry cleanup script : just reserve most recently 5 images per repo

0 gc-step.md

you need jq first.

Steps:

1. download the script && chmod +x
2. enable "delete" inside docker registry container

/etc/docker/registry/config.yml

storage:
  delete:
    enabled: true

3. restart registry container
4. exec script (note: you can use 2>&1 | tee to output the result to both a file and standard output)
5. docker exec -it {registry-id} /bin/registry garbage-collect /etc/docker/registry/config.yml
6. stop registry container && start registry container

1 docker-reg-gc.sh

#!/bin/bash

LIVINGDAYS=${1-150}
DOCKER_REGISTRY="localhost:5000/v2"
ACCEPT_HEADER="Accept: application/vnd.docker.distribution.manifest.v2+json"

function get_repositories {
  curl -Ls "${DOCKER_REGISTRY}"/_catalog?n=10000 | jq -r '."repositories"[]'
}

function get_repository_tags {
  curl -Ls "${DOCKER_REGISTRY}"/"$1"/tags/list?n=10000 | jq -r '."tags"[]' | grep "$2" | sort -r | tail -n +6
}

function get_tag_digest {
  REPOSITORY="$1"
  TAG="$2"
  curl -ILs --header "${ACCEPT_HEADER}" "${DOCKER_REGISTRY}"/"${REPOSITORY}"/manifests/"${TAG}" | grep Docker-Content-Digest | awk '{print $2}' | tr -d '\r'
}

REPORITORIES=$(get_repositories)
echo ALL REPOS: ${REPORITORIES}
echo
for REPOSITORY in ${REPORITORIES[@]}
do
  ENVS=("_PRO_" "_PRE_" "_TEST_" "_DEV_")
  for env in ${ENVS[@]}
  do
    TAGS=$(get_repository_tags "${REPOSITORY}" "$env")
    echo ${REPOSITORY}: ${TAGS}
    echo
    for TAG in ${TAGS[@]}
    do
      echo ${REPOSITORY}:${TAG}
      DIGEST=$(get_tag_digest "${REPOSITORY}" "${TAG}")
      echo "${DOCKER_REGISTRY}"/"${REPOSITORY}"/manifests/"${DIGEST}"
      URL="${DOCKER_REGISTRY}"/"${REPOSITORY}"/manifests/"${DIGEST}"
      curl -s -X DELETE -i $URL
      echo -------------------------------------------------------------------------------------
      echo
    done
  done
done

2 crontab.md

$ crontab -e
0 3 * * * bash /root/docker-reg-gc/cron-docker-reg-gc.sh 2>&1 |tee /root/docker-reg-gc/log/$(date +\%Y-\%m-\%d).log

Note the backslash escaping the % sign. Reference

if you found errors in /var/log/message like this,

crond: sendmail: fatal: parameter inet_interfaces: no local interface found for ::1

maybe you should Disable IPV6 in linux distro and config your postfix to use only ipv4.

if you cannot receive mails from cron, please start postfix similar to systemctl start postfix

3 cron-docker-reg-gc.sh

#!/bin/sh

check() {
  if [[ $? != 0 ]]; then
    npm i nodemailer optimist fs
    node mail.js $(date +%Y-%m-%d)
    exit 1
  fi
}

mkdir -p /root/docker-reg-gc/
cd /root/docker-reg-gc/

echo "exec docker-reg-gc ..."
bash docker-reg-gc.sh; check
echo "exec docker-reg-gc done"

echo "exec garbage-collect command ..."
docker exec registry2 /bin/registry garbage-collect /etc/docker/registry/config.yml; check
echo "exec garbage-collect command done"

echo "restarting registry ..."
docker stop registry2 && docker start registry2; check
echo "restarting registry done"
echo "all done"

4 mail.js

'use strict';
const nodemailer = require('nodemailer');
const fs = require('fs')
const argv = require('optimist').argv;

const logfile = '/root/docker-reg-gc/log/' + argv._[0] + '.log';

// create reusable transporter object using the default SMTP transport
let transporter = nodemailer.createTransport({
    service: 'QQex',
    auth: {
        user: 'you@email',
        pass: 'youpassword'
    }
});

// setup email data with unicode symbols
let mailOptions = {
    from: 'sendfrom@email', // sender address
    to: ['to@email1', 'to@email2'], // list of receivers
    subject: 'ERROR: docker registry crontab error', // Subject line
    text: fs.readFileSync(logfile) // plain text body
};

// send mail with defined transport object
transporter.sendMail(mailOptions, (error, info) => {
    if (error) {
        return console.log(error);
    }
    console.log('Message %s sent: %s', info.messageId, info.response);
});