zpcimon: Allow setting output format and use JSON Lines in systemd unit

Introduce separate '--format' option to set output format. Use the new
JSON Lines format explicitly in the systemd unit. Since JSON Lines
format only uses printable characters this removes the need for passing
'-a' to systemctl status. At the same time JSON-SEQ is more easily
parsable using 'jq --seq' so keep it the default for easier scripting.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

systemd/zpcimon.service.in

@@ -13,7 +13,7 @@ Description=Monitor health of directly attached PCI NIC optical modules
 
 [Service]
 Type=exec
-ExecStart=@usrsbin_path@/zpcimon --send-report --monitor --interval 86400
+ExecStart=@usrsbin_path@/zpcimon --send-report --monitor --format jsonl --interval 86400
 KillMode=control-group
 
 [Install]

zpcimon/zpcimon.8

@@ -84,6 +84,14 @@ on".
 .PP
 .PP
 .
+.SS Output Format Options
+.OD format "" <FORMAT>
+Set the output format out of json, json-seq, jsonl, pairs, and csv. Note that
+only json-seq and jsonl sequence formats are supported for monitoring mode as
+they handle a continuous stream of updates well. While they are not supported
+in query mode.
+.PP
+.
 .SS General Options
 .OD help "h" ""
 Print usage information, then exit.

zpcimon/zpcimon.c

@@ -40,6 +40,8 @@ struct options {
 	bool report;
 	bool module_info;
 	bool quiet;
+	enum util_fmt_t format;
+	bool explicit_format;
 
 	uint32_t interval_seconds;
 };
@@ -63,6 +65,7 @@ static const struct util_prg prg = {
 
 static void parse_cmdline(int argc, char *argv[], struct options *opts)
 {
+	enum util_fmt_t fmt;
 	uint32_t seconds;
 	int cmd, ret;
 
@@ -85,6 +88,12 @@ static void parse_cmdline(int argc, char *argv[], struct options *opts)
 		case OPT_DUMP:
 			opts->module_info = true;
 			break;
+		case OPT_FORMAT:
+			if (!util_fmt_name_to_type(optarg, &fmt))
+				errx(EXIT_FAILURE, "Unknown format %s", optarg);
+			opts->format = fmt;
+			opts->explicit_format = true;
+			break;
 		case 'i':
 			ret = sscanf(optarg, "%u", &seconds);
 			if (ret != 1) {
@@ -224,7 +233,7 @@ static void dump_all_adapter_data(struct opticsmon_ctx *ctx)
 
 static int oneshot_mode(struct opticsmon_ctx *ctx)
 {
-	util_fmt_init(stdout, FMT_JSON, FMT_DEFAULT, API_LEVEL);
+	util_fmt_init(stdout, ctx->opts.format, FMT_DEFAULT, API_LEVEL);
 	if (!ctx->opts.quiet)
 		util_fmt_obj_start(FMT_LIST, "adapters");
 	dump_all_adapter_data(ctx);
@@ -375,7 +384,7 @@ static int monitor_mode(struct opticsmon_ctx *ctx)
 		goto close_timerfd;
 	}
 
-	util_fmt_init(stdout, FMT_JSONSEQ, FMT_DEFAULT, API_LEVEL);
+	util_fmt_init(stdout, ctx->opts.format, FMT_DEFAULT, API_LEVEL);
 	ret = link_mon_nl_waitfd_create(&ctx->lctx, on_link_change, ctx);
 	if (ret) {
 		fprintf(stderr, "Failed to create link monitoring socket\n");
@@ -393,12 +402,42 @@ close_timerfd:
 	return ret;
 }
 
+static bool is_supported_fmt(enum util_fmt_t fmt, bool monitor)
+{
+	switch (fmt) {
+	case FMT_JSON:
+	case FMT_PAIRS:
+		return monitor ? false : true;
+	case FMT_JSONL:
+	case FMT_JSONSEQ:
+		return monitor ? true : false;
+	default:
+		return false;
+	}
+}
+
+static int set_format(struct options *opts)
+{
+	if (!opts->explicit_format)
+		opts->format = (opts->monitor) ? FMT_JSONSEQ : FMT_JSON;
+
+	if (!is_supported_fmt(opts->format, opts->monitor)) {
+		warnx("Format %s is not supported in %s mode",
+		      util_fmt_type_to_name(opts->format), (opts->monitor) ? "monitor" : "query");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 int main(int argc, char **argv)
 {
 	struct opticsmon_ctx ctx = { .opts = { .interval_seconds = 86400 } };
 	int ret;
 
 	parse_cmdline(argc, argv, &ctx.opts);
+	ret = set_format(&ctx.opts);
+	if (ret)
+		return ret;
 	ret = ethtool_nl_connect(&ctx.ethtool_ctx);
 	if (ret)
 		return ret;

zpcimon/zpcimon_cli.h

@@ -7,9 +7,11 @@
 #ifndef OPTICSMON_CLI_H
 #define OPTICSMON_CLI_H
 
+#include "lib/util_fmt.h"
 #include "lib/util_opt.h"
 
 #define OPT_DUMP 128
+#define OPT_FORMAT 129
 
 static struct util_opt opt_vec[] = {
 	UTIL_OPT_SECTION("OPERATION OPTIONS"),
@@ -41,6 +43,13 @@ static struct util_opt opt_vec[] = {
 			"in the absence of link state changes. A value larger than "
 			"24 hours (86400 seconds) is clamped down to 24 hours.",
 	},
+	UTIL_OPT_SECTION("OUTPUT FORMAT OPTIONS"),
+	{
+		.option = { "format", required_argument, NULL, OPT_FORMAT },
+		.argument = "FORMAT",
+		.flags = UTIL_OPT_FLAG_NOSHORT,
+		.desc = "Output format (" FMT_TYPE_NAMES ")",
+	},
 	UTIL_OPT_SECTION("GENERAL OPTIONS"),
 	UTIL_OPT_HELP,
 	UTIL_OPT_VERSION,