Check image updates from Docker Hub

script.sh

#!/usr/bin/env sh
# Check image updates from Docker Hub
# Credits: Eddy Otsutsuki <https://github.com/hypernova7>

get_image_data() {
  curl \
    --silent \
    "https://registry.hub.docker.com/v2/repositories/$1/tags?page_size=100&ordering=last_updated" | jq \
    -r "$2"
}

new_update() {
  local result=false
  local limit_time=86400 # 24hrs in seconds
  local current_time=`date +"%s"` # Convert current time to seconds

  local user=$(echo $1 | cut -d '/' -f1) # Get user
  local repo=$(echo $1 | cut -d '/' -f2) # Get repo
  local version=$([ -z "$2" ] && echo "latest" || echo $2) # Use "latest" if a version is not specified
  user=$([ "$user" = "_" ] && echo "library" || echo $user) # Convert "_" to "library"
  local image="$user/$repo"

  # Get last updated time by version
  local last_updated=`get_image_data $image ".results[] | select(.name==\"$version\") | .last_updated"`

  # Check if image date is not "null"
  if [ "$last_updated" != "null" ]; then
    local last_updated_time=`date -d "$last_updated" +"%s"` # Convert "last_updated" time to seconds
    local days=$((($current_time - $last_updated_time) / $limit_time)) # days passed

    # Check that "days" is less than 1 day
    if [ $days -lt 1 ]; then
      result=true
    fi
  else
    result="IMAGE_NOT_FOUND"
  fi

  echo $result
}

# Usage:
is_new_update=`new_update "_/alpine"`
echo $is_new_update