diff --git a/Gemfile b/Gemfile
index 66fb75010cbf1924bf27f734c630cb4b6796b012..a2d226e622437348ce074f8109fa343055bc55f1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -15,7 +15,8 @@ gem 'ruby-bandwidth-iris', '~> 2.7'
 gem 'goliath'
 gem 'lazy_object'
 gem 'value_semantics'
-gem 'log4r'
+gem 'amazing_print'
+gem 'ougai'
 gem 'multibases'
 gem 'multihashes'
 gem 'rack', '< 2'
diff --git a/lib/background_log.rb b/lib/background_log.rb
new file mode 100644
index 0000000000000000000000000000000000000000..e1f9e8d556dd07e9518246c8ad6bcbf642174944
--- /dev/null
+++ b/lib/background_log.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class BackgroundLog < IO
+	def initialize(io)
+		@io = io
+		@q = Queue.new
+		thread
+		at_exit do
+			@q << :done
+			thread.join
+		end
+	end
+
+	def thread
+		@thread ||= Thread.new do
+			loop do
+				m = @q.pop
+				break if m == :done
+
+				@io.write m
+			end
+		end
+	end
+
+	def write(s)
+		@q << s
+	end
+end
diff --git a/sgx-bwmsgsv2.rb b/sgx-bwmsgsv2.rb
index d6d9caf9998ab0fe0854b5f9b0f30eb7d0df4c33..d64e55168bcd32ce116b27939bb964a78e0e9b7a 100755
--- a/sgx-bwmsgsv2.rb
+++ b/sgx-bwmsgsv2.rb
@@ -34,7 +34,7 @@ require 'webrick'
 
 require 'goliath/api'
 require 'goliath/server'
-require 'log4r'
+require "ougai"
 
 require 'em_promise'
 require 'em-synchrony'
@@ -46,6 +46,24 @@ require_relative 'lib/registration_repo'
 
 Sentry.init
 
+require_relative 'lib/background_log'
+
+$stdout.sync = true
+LOG = Ougai::Logger.new(ENV["ENV"] == "test" ? $stdout : BackgroundLog.new($stdout))
+LOG.level = ENV.fetch("LOG_LEVEL", "info")
+LOG.formatter = Ougai::Formatters::Readable.new(
+	nil,
+	nil,
+	plain: !$stdout.isatty
+)
+Blather.logger = LOG
+EM::Hiredis.logger = LOG
+
+Sentry.init do |config|
+	config.logger = LOG
+	config.breadcrumbs_logger = [:sentry_logger]
+end
+
 BADWORD_LIST = [
 	"marijuana",
 	"psilocybin",
@@ -140,16 +158,13 @@ MMS_MIME_TYPES = [
 
 def panic(e)
 	if e.is_a?(Exception)
-		puts "[#{Time.now.iso8601}] Shutting down gateway due to exception: #{e.message}"
 		Sentry.capture_exception(e, hint: { background: false })
-		puts e.backtrace
 	else
-		puts "[#{Time.now.iso8601}] Shutting down gateway due to non-exception:"
-		p e
 		Sentry.capture_message(e.to_s, hint: { background: false })
 	end
+	LOG.fatal("Shutting down gateway", e)
 	SGXbwmsgsv2.shutdown
-	puts 'Gateway has terminated.'
+	LOG.info "Gateway has terminated"
 	EM.stop
 end
 
@@ -228,9 +243,7 @@ protected
 	end
 
 	def handle_error(scope, stanza, e)
-		puts "Error raised during #{scope.transaction_name}: #{e.class}"
-		puts e.message
-		puts e.backtrace
+		LOG.error("Error during #{scope.transaction_name}", e)
 		Sentry.capture_exception(e) unless e.is_a?(Sentry::Error)
 		scope.get_transaction&.set_status("internal_error")
 		return if e.respond_to?(:replied?) && e.replied?
@@ -275,13 +288,13 @@ module SGXbwmsgsv2
 		# we assume media_url is one of these (always the case so far):
 		#  https://messaging.bandwidth.com/api/v2/users/[u]/media/[path]
 
-		puts 'ORIG_URL: ' + media_url
+		LOG.debug("Original media URL", url: media_url)
 		usr = to
 		if media_url.start_with?('https://messaging.bandwidth.com/api/v2/users/')
 			pth = media_url.split('/', 9)[8]
 			# the caller must guarantee that 'to' is a bare JID
 			media_url = ARGV[6] + WEBrick::HTTPUtils.escape(usr) + '/' + pth
-			puts 'PROX_URL: ' + media_url
+			LOG.debug("Proxied media URL", url: media_url)
 		end
 
 		msg = m ? m.copy : Blather::Stanza::Message.new(to, "")
@@ -325,7 +338,6 @@ module SGXbwmsgsv2
 		m.to = jid
 		m.from = "#{users_num}@#{ARGV[0]}"
 
-		puts 'XRESPONSE0: ' + m.inspect
 		write_to_stream m
 
 		# Emit pass-through event. Thru events don't capture a timestamp because XMPP
@@ -352,7 +364,6 @@ module SGXbwmsgsv2
 		rcvd['id'] = m.id
 		rcpt.add_child(rcvd)
 
-		puts 'XRESPONSE1: ' + rcpt.inspect
 		write_to_stream rcpt
 	end
 
@@ -400,11 +411,11 @@ module SGXbwmsgsv2
 		usern)
 		un = s.at("oob|x > oob|url", oob: "jabber:x:oob")
 		unless un
-			puts "MMSOOB: no url node found so process as normal"
+			LOG.debug "No OOB URL node, processing as normal"
 			return to_catapult(s, nil, num_dest, user_id, token,
 				secret, usern)
 		end
-		puts "MMSOOB: found a url node - checking if to make MMS..."
+		LOG.debug "Found OOB URL node, checking MMS eligibility"
 
 		body = s.respond_to?(:body) ? s.body : ''
 
@@ -427,10 +438,7 @@ module SGXbwmsgsv2
 				# some clients send URI in both body & <url/> so delete
 				s.body = body.sub(/\s*#{Regexp.escape(un.text)}\s*$/, '')
 
-				puts "MMSOOB: url text is '#{un.text}'"
-				puts "MMSOOB: the body is '#{body.to_s.strip}'"
-
-				puts "MMSOOB: sending MMS since found OOB & user asked"
+				LOG.debug("OOB MMS details", url: un.text, body: body.to_s.strip)
 				to_catapult(s, un.text, num_dest, user_id, token, secret, usern)
 			end
 		}
@@ -523,7 +531,7 @@ module SGXbwmsgsv2
 					[:cancel, 'item-not-found']
 				)
 			end
-			puts "ADRXEP: found an addresses node - iterate addrs.."
+			LOG.debug "Found addresses node, iterating"
 
 			nums = []
 			an.children.each do |e|
@@ -585,7 +593,7 @@ module SGXbwmsgsv2
 
 	message :error? do |m|
 		# TODO: report it somewhere/somehow - eat for now so no err loop
-		puts "EATERROR1: #{m.inspect}"
+		LOG.warn("Eating error stanza", stanza: m.inspect)
 		true
 	end
 
@@ -636,15 +644,12 @@ module SGXbwmsgsv2
 	end
 
 	subscription :request? do |p|
-		puts "PRESENCE1: #{p.inspect}"
-
 		# subscriptions are allowed from anyone - send reply immediately
 		msg = Blather::Stanza::Presence.new
 		msg.to = p.from
 		msg.from = p.to
 		msg.type = :subscribed
 
-		puts 'RESPONSE5a: ' + msg.inspect
 		write_to_stream msg
 
 		# send a <presence> immediately; not automatically probed for it
@@ -659,7 +664,6 @@ module SGXbwmsgsv2
 		msg.to = p.from
 		msg.from = p.to.to_s + '/sgx'
 
-		puts 'RESPONSE5b: ' + msg.inspect
 		write_to_stream msg
 
 		# need to subscribe back so Conversations displays images inline
@@ -668,13 +672,10 @@ module SGXbwmsgsv2
 		msg.from = p.to.to_s.split('/', 2)[0]
 		msg.type = :subscribe
 
-		puts 'RESPONSE5c: ' + msg.inspect
 		write_to_stream msg
 	end
 
 	presence :probe? do |p|
-		puts 'PRESENCE2: ' + p.inspect
-
 		caps = Blather::Stanza::Capabilities.new
 		# TODO: user a better node URI (?)
 		caps.node = 'http://catapult.sgx.soprani.ca/'
@@ -685,7 +686,6 @@ module SGXbwmsgsv2
 		msg.to = p.from
 		msg.from = p.to.to_s + '/sgx'
 
-		puts 'RESPONSE6: ' + msg.inspect
 		write_to_stream msg
 	end
 
@@ -710,7 +710,6 @@ module SGXbwmsgsv2
 					reply.items = []
 				end
 
-				puts 'RESPONSE_CMD_DISCO: ' + reply.inspect
 				write_to_stream reply
 			}
 		}.catch { |e|
@@ -727,8 +726,7 @@ module SGXbwmsgsv2
 		#  :error it should be ignored (as the below does currently);
 		#  review specification to see how to handle other type values
 		if i.type != :get
-			puts 'DISCO iq rcvd, of non-get type "' + i.type.to_s +
-				'" for message "' + i.inspect + '"; ignoring...'
+			LOG.warn("Ignoring non-get disco IQ", type: i.type.to_s, stanza: i.inspect)
 			next
 		end
 
@@ -742,7 +740,6 @@ module SGXbwmsgsv2
 			msg.identities = user_cap_identities
 			msg.features = user_cap_features
 
-			puts 'RESPONSE7: ' + msg.inspect
 			write_to_stream msg
 			next
 		end
@@ -809,7 +806,7 @@ module SGXbwmsgsv2
 				JSON.parse(response)
 				# TODO: confirm response is array - could be empty
 
-				puts "register got str #{response.to_s[0..999]}"
+				LOG.debug("Registration verify response", response: response.to_s[0..999])
 
 				check_then_register(
 					i,
@@ -884,8 +881,6 @@ module SGXbwmsgsv2
 	end
 
 	ibr do |i|
-		puts "IQ: #{i.inspect}"
-
 		case i.type
 		when :set
 			process_registration(i)
@@ -893,7 +888,6 @@ module SGXbwmsgsv2
 			bare_jid = i.from.stripped
 			@registration_repo.find(bare_jid).then { |creds|
 				reply = registration_form(i.reply, creds.last)
-				puts "RESPONSE2: #{reply.inspect}"
 				write_to_stream reply
 			}
 		else
@@ -937,7 +931,6 @@ module SGXbwmsgsv2
 			reply.command.add_child(form)
 			reply.allowed_actions = [:complete]
 
-			puts "RESPONSE_CMD_FORM: #{reply.inspect}"
 			write_to_stream reply
 		}.catch { |e|
 			if e.is_a?(Array) && [2, 3].include?(e.length)
@@ -1041,24 +1034,20 @@ class WebhookHandler < Goliath::API
 		@registration_repo = RegistrationRepo.new
 		# TODO: add timestamp grab here, and MUST include ./tai version
 
-		puts 'ENV: ' + env.reject { |k| k == 'params' }.to_s
+		LOG.debug("Webhook request env", env: env.reject { |k| k == 'params' })
 
 		if params.empty?
-			puts 'PARAMS empty!'
+			LOG.warn "Empty webhook params"
 			return [200, {}, "OK"]
 		end
 
 		if env['REQUEST_URI'] != '/'
-			puts 'BADREQUEST1: non-/ request "' +
-				env['REQUEST_URI'] + '", method "' +
-				env['REQUEST_METHOD'] + '"'
+			LOG.warn("Non-/ request", uri: env['REQUEST_URI'], method: env['REQUEST_METHOD'])
 			return [200, {}, "OK"]
 		end
 
 		if env['REQUEST_METHOD'] != 'POST'
-			puts 'BADREQUEST2: non-POST request; URI: "' +
-				env['REQUEST_URI'] + '", method "' +
-				env['REQUEST_METHOD'] + '"'
+			LOG.warn("Non-POST request", uri: env['REQUEST_URI'], method: env['REQUEST_METHOD'])
 			return [200, {}, "OK"]
 		end
 
@@ -1076,7 +1065,7 @@ class WebhookHandler < Goliath::API
 		elsif jparams['direction'] == 'out'
 			[jparams['from'], jparams['owner']] # NOTE: for outbound, 'from' == 'owner'
 		else
-			puts "big prob: '#{jparams['direction']}'"
+			LOG.error("Unexpected message direction", direction: jparams['direction'])
 			[jparams['from'], jparams['owner']]
 		end
 
@@ -1084,15 +1073,18 @@ class WebhookHandler < Goliath::API
 		return [400, {}, "Missing params\n"] unless jparams['to'].is_a?(Array)
 		return [400, {}, "Missing params\n"] if jparams['to'].empty?
 
-		puts "BODY - messageId: #{jparams['id']}" \
-			", eventType: #{type}" \
-			", time: #{jparams['time']}" \
-			", direction: #{jparams['direction']}" \
-			", deliveryState: #{jparams['deliveryState'] || 'NONE'}" \
-			", errorCode: #{jparams['errorCode'] || 'NONE'}" \
-			", description: #{jparams['description'] || 'NONE'}" \
-			", tag: #{jparams['tag'] || 'NONE'}" \
-			", media: #{jparams['media'] || 'NONE'}"
+		LOG.info(
+			"Webhook message",
+			message_id: jparams['id'],
+			event_type: type,
+			time: jparams['time'],
+			direction: jparams['direction'],
+			delivery_state: jparams['deliveryState'],
+			error_code: jparams['errorCode'],
+			description: jparams['description'],
+			tag: jparams['tag'],
+			media: jparams['media']
+		)
 
 		if others_num[0] != '+'
 			# TODO: check that others_num actually a shortcode first
@@ -1103,7 +1095,7 @@ class WebhookHandler < Goliath::API
 		bare_jid = @registration_repo.find_jid(users_num).sync
 
 		if !bare_jid
-			puts "jid_key for (#{users_num}) DNE; BW API misconfigured?"
+			LOG.warn("JID not found for number, BW API misconfigured?", users_num: users_num)
 
 			return [403, {}, "Customer not found\n"]
 		end
@@ -1152,9 +1144,6 @@ class WebhookHandler < Goliath::API
 					end
 
 					msg.add_child(addrs)
-
-					# TODO: delete
-					puts "RESPONSE9: #{msg.inspect}"
 				end
 
 				media_urls = Array(jparams['media']).map { |media_url|
@@ -1197,7 +1186,7 @@ class WebhookHandler < Goliath::API
 					" with text: " + jparams['text']
 
 				# TODO: log/notify of this properly
-				puts text
+				LOG.warn("Unknown inbound message type", text: text)
 			end
 
 			# If text is not empty, but there isn't a msg,
@@ -1237,7 +1226,7 @@ class WebhookHandler < Goliath::API
 						bandwidth_id: jparams['id']
 					).emit(REDIS)
 				end
-				puts "WARN! group no rcpt: #{users_num}"
+				LOG.warn("Group message, skipping receipt", users_num: users_num)
 				return [200, {}, "OK"]
 			end
 
@@ -1277,12 +1266,12 @@ class WebhookHandler < Goliath::API
 				others_num = params['_json'][0]['to']
 			else
 				# TODO: notify somehow of unknown state receivd?
-				puts "message with id #{id} has "\
-					"other type #{type}"
+				LOG.warn("Unknown outbound message type", id: id, type: type)
 				return [200, {}, "OK"]
 			end
 
-			puts "RESPONSE4: #{msg.inspect}"
+			# Keeping this due to the `msg.from=` shuffle just below
+			LOG.debug("Outbound callback response", stanza: msg.inspect)
 		end
 
 		# if message-failed, we already set msg.from
@@ -1336,27 +1325,23 @@ class WebhookHandler < Goliath::API
 		[200, {}, "OK"]
 	rescue Exception => e
 		Sentry.capture_exception(e)
-		p e
 		[500, {}, "Error"]
 	end
 end
 
 at_exit do
-	$stdout.sync = true
-
-	puts "Soprani.ca/SMS Gateway for XMPP - Bandwidth API V2\n"\
-		"==>> last commit of this version is " + `git rev-parse HEAD` + "\n"
+	LOG.info("Soprani.ca/SMS Gateway for XMPP - Bandwidth API V2",
+		version: `git rev-parse HEAD`.chomp)
 
 	if ARGV.size != 7
-		puts "Usage: sgx-bwmsgsv2.rb <component_jid> "\
+		warn "Usage: sgx-bwmsgsv2.rb <component_jid> "\
 			"<component_password> <server_hostname> "\
 			"<server_port> <application_id> "\
 			"<http_listen_port> <mms_proxy_prefix_url>"
 		exit 0
 	end
 
-	t = Time.now
-	puts "LOG %d.%09d: starting...\n\n" % [t.to_i, t.nsec]
+	LOG.info "Starting"
 
 	EM.run do
 		REDIS = EM::Hiredis.connect
@@ -1373,17 +1358,15 @@ at_exit do
 		server = Goliath::Server.new('0.0.0.0', ARGV[5].to_i)
 		server.api = WebhookHandler.new
 		server.app = Goliath::Rack::Builder.build(server.api.class, server.api)
-		server.logger = Log4r::Logger.new('goliath')
-		server.logger.add(Log4r::StdoutOutputter.new('console'))
-		server.logger.level = Log4r::INFO
+		server.logger = LOG
 		server.start do
 			["INT", "TERM"].each do |sig|
 				trap(sig) do
 					EM.defer do
-						puts 'Shutting down gateway...'
+						LOG.info "Shutting down gateway"
 						SGXbwmsgsv2.shutdown
 
-						puts 'Gateway has terminated.'
+						LOG.info "Gateway has terminated"
 						EM.stop
 					end
 				end