feat(func): Add JSON logging func

Update central logging steering function to reference this new JSON logging backend function.

cfddns.sh

@@ -113,6 +113,31 @@ standardizeLogLevels() {
   esac
 }
 
+# $1: message, $2: level, $3: status, [$4: operation], [$5: code]
+writeJsonLog() {
+  # not enough information to generate a meaningful log message
+  if [ -z "$1" ] || [ $# -lt 3 ]; then
+    return
+  fi
+
+  JSON_PROPS="$(
+    jq --null-input \
+      --arg timestamp "$(getTimeStamp)" \
+      --arg hostname "$(getHostname)" \
+      --arg pName "$LOG_PROGRAM_NAME" \
+      --arg pid "$$" \
+      --arg level "$(standardizeLogLevels "$2")" \
+      --arg status "$(uppercase "$3")" \
+      --arg message "$1" \
+      --arg operation "${4:-UNSPECIFIED}" \
+      --arg code "${5:-0}" \
+      '{"timestamp":$timestamp, "hostname":$hostname, "programName":$pName, "pid":$pid, "level":$level, "status":$status, "message":$message, "operation":$operation, "code":$code}' \
+  )"
+
+  printf "%s\n" "$JSON_PROPS" >>"$logFile"
+  return
+}
+
 # modified syslog fmt: <ISO-8601 timestamp> <hostname> <tag>[pid]: [LEVEL:$2] [STATUS:$3] <MESSAGE:$1> (<OPERATION:$4>:<CODE:$5>)
 writePlainTextLog() {
   # not enough information to generate a meaningful log message
@@ -127,13 +152,13 @@ writePlainTextLog() {
 }
 
 writeLog() {
-  ([ "$logToNone" ]) && return
+  ([ "$logToNone" -eq 1 ]) && return
 
   PT_LOG_LEVEL="$(standardizeLogLevels "$2")"
   ([ "$logDebug" -eq 0 ] && [ "$PT_LOG_LEVEL" = "DEBUG" ]) && return
 
-  ([ "$logToJournal" ]) && return # TODO: replace this with function when implemented
-  ([ "$useJsonLogFmt" -eq 1 ]) && return # TODO: replace this with function when implemented
+  ([ "$logToJournal" -eq 1 ]) && return # TODO: replace this with function when implemented
+  ([ "$useJsonLogFmt" -eq 1 ]) && writeJsonLog "$@"
   ([ "$useSyslogLogFmt" -eq 1 ]) && writePlainTextLog "$@"
 }