restic-append-only-backup

script.rb

#!/usr/bin/env ruby

require 'date'
require 'json'
require 'open3'

File.readlines(".env", chomp: true).select { !_1.start_with?('#') && !_1.strip.empty? }.each {
  k, v =_1.strip.split('=')
  ENV[k] = v
}

raise 'must set REMOTE env var' unless remote = ENV["REMOTE"]
raise 'must set REPOSITORY env var' unless repo = ENV["REPOSITORY"]
raise 'must set RESTIC_COMPRESSION env var' unless compression = ENV["RESTIC_COMPRESSION"]

script = "restic backup --compression=#{compression} -r #{remote}/#{repo} --exclude-file=exclude --files-from=include"

puts "running dry-run to see if changes occurred";

output = ""

begin
  Open3.popen3(ENV, "#{script} --quiet --json --dry-run") { |i, o, e, t|
    output = o.read
    puts "dry run yielded: #{output}" 

    raise "dry run failed with #{t.value} #{e.read}" unless t.value.success?
  }
rescue => e
  raise "unable to run dry run: #{e}"
end

begin
  output_json = JSON.parse(output);
rescue JSON::ParserError => e
  raise "result from dry run couldn't be parsed to JSON: #{e}"
end

raise "output didn't contain 'files_new'" unless new_files = output_json["files_new"]
raise "output didn't contain 'files_changed'" unless changed_files = output_json["files_changed"]
raise "output didn't contain 'dirs_new'" unless new_dirs = output_json["dirs_new"]
raise "output didn't contain 'dirs_changed'" unless changed_dirs = output_json["dirs_changed"]

total_changes = new_files + changed_files + new_dirs + changed_dirs

puts "total changes: #{total_changes}"

if total_changes == 0 then
  puts "no changes detected, not creating snapshot"
  return
end

puts "detected changes, running backup"

begin
  Open3.popen3(ENV, "#{script}") { |i, o, e, t|
    output = o.read
    puts "run yielded: #{output}" 

    raise "restic backup failed with #{t.value}" unless t.value.success?
  }
rescue => e
  raise "unable to run backup: #{e}"
end