feat: json log format

Introduce a json log format that can be invoked by passing `log-format json` in your config.

Signed-off-by: Johan Bergström <[email protected]>

Author: jbergstroem

Diff for: src/config.c

@@ -153,7 +153,7 @@ configEnum propagation_error_behavior_enum[] = {
     {"panic-on-replicas", PROPAGATION_ERR_BEHAVIOR_PANIC_ON_REPLICAS},
     {NULL, 0}};
 
-configEnum log_format_enum[] = {{"legacy", LOG_FORMAT_LEGACY}, {"logfmt", LOG_FORMAT_LOGFMT}, {NULL, 0}};
+configEnum log_format_enum[] = {{"legacy", LOG_FORMAT_LEGACY}, {"logfmt", LOG_FORMAT_LOGFMT}, {"json", LOG_FORMAT_JSON}, {NULL, 0}};
 
 configEnum log_timestamp_format_enum[] = {{"legacy", LOG_TIMESTAMP_LEGACY},
                                           {"iso8601", LOG_TIMESTAMP_ISO8601},

Diff for: src/server.c

@@ -240,6 +240,18 @@ void serverLogRaw(int level, const char *msg) {
             }
             break;
 
+        case LOG_FORMAT_JSON:
+            if (hasInvalidLogfmtChar(msg)) {
+                char safemsg[LOG_MAX_LEN];
+                filterInvalidLogfmtChar(safemsg, LOG_MAX_LEN, msg);
+                fprintf(fp, "{\"pid\":%d,\"role\":\"%s\",\"timestamp\":\"%s\",\"level\":\"%s\",\"message\":\"%s\"}\n", (int)getpid(), roles[role_index],
+                        buf, verbose_level[level], safemsg);
+            } else {
+                fprintf(fp, "{\"pid\":%d,\"role\":\"%s\",\"timestamp\":\"%s\",\"level\":\"%s\",\"message\":\"%s\"}\n", (int)getpid(), roles[role_index],
+                        buf, verbose_level[level], msg);
+            }
+            break;
+
         case LOG_FORMAT_LEGACY:
             fprintf(fp, "%d:%c %s %c %s\n", (int)getpid(), role_chars[role_index], buf, c[level], msg);
             break;

Diff for: src/server.h

@@ -595,7 +595,8 @@ typedef enum {
 
 /* Sets log format */
 typedef enum { LOG_FORMAT_LEGACY = 0,
-               LOG_FORMAT_LOGFMT } log_format_type;
+               LOG_FORMAT_LOGFMT,
+               LOG_FORMAT_JSON } log_format_type;
 
 /* Sets log timestamp format */
 typedef enum { LOG_TIMESTAMP_LEGACY = 0,

Diff for: valkey.conf

@@ -401,6 +401,7 @@ loglevel notice
 #
 # - legacy: the default, traditional log format
 # - logfmt: a structured log format; see https://www.brandur.org/logfmt
+# - json: a structured log format; see https://json.org/
 #
 # log-format legacy