#!/usr/bin/env ruby
# prints the Docker Image Labels for ECR images matching a given tag expression
require 'aws-sdk'

repo         = 'mdsol/operationalanalytics/build'
tag_match    = /feature-sprint3\.maps/
sort_field   = 'com.mdsol.12f-buildDate'
reverse_sort = true                         # reverse is nicer when date sorting
label_filter = /\Acom\.mdsol\.12f-appDesc/  # values in these labels are ignored
date_fields  = /\Acom\.mdsol\.12f-.*Date\Z/ # these values get DateTime parsed
region       = 'us-east-1'

# get all images for repo (<= 100)
ecr      = Aws::ECR::Client.new(region: region)
STDERR.printf "Fetching all images from Repo %s in %s...\n", repo, region
all_imgs = ecr.describe_images(repository_name: repo).image_details

# filter images by tag_match
img_info = all_imgs.select{|i| !(i.image_tags.select {|t| t =~ tag_match}).empty?}

# get image details with another API call
STDERR.printf "Fetching image details for %d matching images...\n", img_info.count
details = ecr.batch_get_image(
  repository_name: repo,
  image_ids: img_info.map{|i| { image_digest: i.image_digest}}).images

# extract Docker Labels, excluding label_filter, and parsing DateTime fields
STDERR.printf "Extracting image manifests...\n"
manifests = details.map{|d| JSON.parse(JSON.parse(
  d.image_manifest)['history'].first['v1Compatibility'])}
labels = manifests.map{|m| m['config']['Labels'].select{|k,v| k !~ label_filter}}

# sort as needed
if (! sort_field.empty?) && (labels.first.has_key?(sort_field))
  labels.sort! do |a,b|
    if a =~ date_fields
      DateTime.parse(a[sort_field]) <=> DateTime.parse(b[sort_field])
    else
      a[sort_field] <=> b[sort_field]
    end
  end
end
labels.reverse! if reverse_sort

puts JSON.pretty_generate(labels) # output