Merge pull request #21883 from albers/completion-syslog-format

bash completion for `--log-opt syslog-format`

contrib/completion/bash/docker

@@ -415,7 +415,7 @@ __docker_complete_log_options() {
 	local gelf_options="env gelf-address gelf-compression-level gelf-compression-type labels tag"
 	local journald_options="env labels tag"
 	local json_file_options="env labels max-file max-size"
-	local syslog_options="syslog-address syslog-tls-ca-cert syslog-tls-cert syslog-tls-key syslog-tls-skip-verify syslog-facility tag"
+	local syslog_options="syslog-address syslog-format syslog-tls-ca-cert syslog-tls-cert syslog-tls-key syslog-tls-skip-verify syslog-facility tag"
 	local splunk_options="env labels splunk-caname splunk-capath splunk-index splunk-insecureskipverify splunk-source splunk-sourcetype splunk-token splunk-url tag"
 
 	local all_options="$fluentd_options $gcplogs_options $gelf_options $journald_options $json_file_options $syslog_options $splunk_options"
@@ -507,6 +507,10 @@ __docker_complete_log_driver_options() {
 			" -- "${cur##*=}" ) )
 			return
 			;;
+		syslog-format)
+			COMPREPLY=( $( compgen -W "rfc3164 rfc5424 rfc5424micro" -- "${cur##*=}" ) )
+			return
+			;;
 		syslog-tls-@(ca-cert|cert|key))
 			_filedir
 			return