Can we have an option to disable journal auto-detection?
In my case I want to redirect the DPDK to our own tracing infrastructure and for that I use the fopencookie myself and redirect it to our own system. The journal will force it out and I'll need to ensure that the environment variable is not set, which is doable but I'd rather not need to mess with the environment and just set a flag in dpdk options to disable the journal.

On Thu, Oct 24, 2024 at 10:09 PM Stephen Hemminger <stephen@networkplumber.org> wrote:
If DPDK application is being run as a systemd service, then
it can use the journal protocol which allows putting more information
in the log such as priority and other information.

The use of journal protocol is automatically detected and
handled.  Rather than having a dependency on libsystemd,
just use the protocol directly as defined in:
        https://url.avanan.click/v2/r01/___https://systemd.io/JOURNAL_NATIVE_PROTOCOL/___.YXAzOndla2E6YTpnOjc1MmU1YTVhODIzMWJiMTdkNTBhNzE4MDVhNDc2MTBhOjc6MTNlMjpkODkwMzM0ZTExZTQyZTBmZDY2NmI4YmRjMzY1Nzk1NTJlZjYyMWI0MjE1MjYyOTU4MTg3YjE3YjA1Y2NjMDA4OnA6VDpO

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/log/log.c          |   7 +-
 lib/log/log_internal.h |   3 +
 lib/log/log_journal.c  | 154 +++++++++++++++++++++++++++++++++++++++++
 lib/log/log_private.h  |  14 ++++
 lib/log/log_syslog.c   |   9 +++
 lib/log/meson.build    |   4 ++
 lib/log/version.map    |   1 +
 7 files changed, 189 insertions(+), 3 deletions(-)
 create mode 100644 lib/log/log_journal.c

diff --git a/lib/log/log.c b/lib/log/log.c
index 7bf4548858..343f9d77b7 100644
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -508,13 +508,14 @@ eal_log_init(const char *id)
 {
        FILE *logf = NULL;

-       if (log_syslog_enabled())
+       if (log_journal_enabled())
+               logf = log_journal_open(id);
+       else if (log_syslog_enabled())
                logf = log_syslog_open(id);

        if (logf)
                rte_openlog_stream(logf);
-
-       if (log_timestamp_enabled())
+       else if (log_timestamp_enabled())
                rte_logs.print_func = log_print_with_timestamp;
        else
                rte_logs.print_func = vfprintf;
diff --git a/lib/log/log_internal.h b/lib/log/log_internal.h
index 8ef195a6ec..731c099984 100644
--- a/lib/log/log_internal.h
+++ b/lib/log/log_internal.h
@@ -35,6 +35,9 @@ int eal_log_save_pattern(const char *pattern, uint32_t level);
 __rte_internal
 int eal_log_syslog(const char *name);

+__rte_internal
+int eal_log_journal(const char *opt);
+
 /*
  * Convert log level to string.
  */
diff --git a/lib/log/log_journal.c b/lib/log/log_journal.c
new file mode 100644
index 0000000000..43341aa233
--- /dev/null
+++ b/lib/log/log_journal.c
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <rte_common.h>
+#include <rte_log.h>
+
+#include "log_internal.h"
+#include "log_private.h"
+
+/*
+ * Send structured message using journal protocol
+ * See: https://url.avanan.click/v2/r01/___https://systemd.io/JOURNAL_NATIVE_PROTOCOL/___.YXAzOndla2E6YTpnOjc1MmU1YTVhODIzMWJiMTdkNTBhNzE4MDVhNDc2MTBhOjc6NTQxZDoyMWQ3NGFjZGMwYWE0M2RhZTM4OTc0ZmJjNGY1NzFkZTFlNTZmMTEwM2I3ZDNhN2U3ZDkxNzFmZjg4ODU3NGQxOnA6VDpO
+ *
+ * Uses writev() to ensure that whole log message is in one datagram
+ */
+static int
+journal_send(int fd, const char *buf, size_t len)
+{
+       struct iovec iov[4];
+       unsigned int n = 0;
+       int priority = rte_log_cur_msg_loglevel() - 1;
+       char msg[] = "MESSAGE=";
+       char newline = '\n';
+       char pbuf[32];  /* "PRIORITY=N\n" */
+
+       iov[n].iov_base = msg;
+       iov[n++].iov_len = strlen(msg);
+
+       iov[n].iov_base = (char *)(uintptr_t)buf;
+       iov[n++].iov_len = len;
+
+       /* if message doesn't end with newline, one will be applied. */
+       if (buf[len - 1] != '\n') {
+               iov[n].iov_base = &newline;
+               iov[n++].iov_len = 1;
+       }
+
+       /* priority value between 0 ("emerg") and 7 ("debug") */
+       iov[n].iov_base = pbuf;
+       iov[n++].iov_len = snprintf(pbuf, sizeof(pbuf),
+                                   "PRIORITY=%d\n", priority);
+       return writev(fd, iov, n);
+}
+
+
+/* wrapper for log stream to put messages into journal */
+static ssize_t
+journal_log_write(void *c, const char *buf, size_t size)
+{
+       int fd = (uintptr_t)c;
+
+       return journal_send(fd, buf, size);
+}
+
+static int
+journal_log_close(void *c)
+{
+       int fd = (uintptr_t)c;
+
+       close(fd);
+       return 0;
+}
+
+static cookie_io_functions_t journal_log_func = {
+       .write = journal_log_write,
+       .close = journal_log_close,
+};
+
+/*
+ * Check if stderr is going to system journal.
+ * This is the documented way to handle systemd journal
+ *
+ * See: https://url.avanan.click/v2/r01/___https://systemd.io/JOURNAL_NATIVE_PROTOCOL/___.YXAzOndla2E6YTpnOjc1MmU1YTVhODIzMWJiMTdkNTBhNzE4MDVhNDc2MTBhOjc6NjA4MzpiZGFiZDNiOGRhZDVhMDBkOGI1N2NmZTBjYjUyYjYzNmY5NTU3NGMyZjVmOTk2MTA4YjQxNzMxNDBmNzZhYWE4OnA6VDpO
+ */
+bool
+log_journal_enabled(void)
+{
+       char *jenv, *endp = NULL;
+       struct stat st;
+       unsigned long dev, ino;
+
+       jenv = getenv("JOURNAL_STREAM");
+       if (jenv == NULL)
+               return false;
+
+       if (fstat(STDERR_FILENO, &st) < 0)
+               return false;
+
+       /* systemd sets colon-separated list of device and inode number */
+       dev = strtoul(jenv, &endp, 10);
+       if (endp == NULL || *endp != ':')
+               return false;   /* missing colon */
+
+       ino = strtoul(endp + 1, NULL, 10);
+
+       return dev == st.st_dev && ino == st.st_ino;
+}
+
+/* Connect to systemd's journal service */
+FILE *log_journal_open(const char *id)
+{
+       char syslog_id[PATH_MAX];
+       FILE *log_stream;
+       int len;
+       struct sockaddr_un sun = {
+               .sun_family = AF_UNIX,
+               .sun_path = "/run/systemd/journal/socket",
+       };
+       int jfd = -1;
+
+       len = snprintf(syslog_id, sizeof(syslog_id),
+                      "SYSLOG_IDENTIFIER=%s\nSYSLOG_PID=%u", id, getpid());
+
+       /* Detect truncation of message and fallback to no journal */
+       if (len >= (int)sizeof(syslog_id))
+               return NULL;
+
+       jfd = socket(AF_UNIX, SOCK_DGRAM, 0);
+       if (jfd < 0) {
+               perror("socket");
+               goto error;
+       }
+
+       if (connect(jfd, (struct sockaddr *)&sun, sizeof(sun)) < 0) {
+               perror("connect");
+               goto error;
+       }
+
+       /* Send identifier as first message */
+       if (write(jfd, syslog_id, len) != len) {
+               perror("write");
+               goto error;
+       }
+
+       /* redirect other log messages to journal */
+       log_stream = fopencookie((void *)(uintptr_t)jfd, "w", journal_log_func);
+       if (log_stream != NULL)
+               return log_stream;
+
+error:
+       close(jfd);
+       return NULL;
+}
diff --git a/lib/log/log_private.h b/lib/log/log_private.h
index 86eaf3f910..37895949f6 100644
--- a/lib/log/log_private.h
+++ b/lib/log/log_private.h
@@ -22,6 +22,20 @@ bool log_syslog_enabled(void);
 FILE *log_syslog_open(const char *id);
 #endif

+#ifdef RTE_EXEC_ENV_LINUX
+bool log_journal_enabled(void);
+FILE *log_journal_open(const char *id);
+#else
+static inline bool log_journal_enabled(void)
+{
+       return false;
+}
+static inline FILE *log_journal_open(const char *id __rte_unused)
+{
+       return NULL;
+}
+#endif /* !RTE_EXEC_ENV_LINUX */
+
 bool log_timestamp_enabled(void);
 ssize_t log_timestamp(char *tsbuf, size_t tsbuflen);

diff --git a/lib/log/log_syslog.c b/lib/log/log_syslog.c
index 7d29e3a00f..c23b19fe89 100644
--- a/lib/log/log_syslog.c
+++ b/lib/log/log_syslog.c
@@ -18,6 +18,10 @@

 static int log_facility;

+/*
+ * Usable list of facilities
+ * Skip kern, mark, and security
+ */
 static const struct {
        const char *name;
        int value;
@@ -48,6 +52,11 @@ eal_log_syslog(const char *name)
 {
        unsigned int i;

+       if (name == NULL) {
+               log_facility = LOG_DAEMON;
+               return 0;
+       }
+
        for (i = 0; i < RTE_DIM(facilitys); i++) {
                if (!strcmp(name, facilitys[i].name)) {
                        log_facility = facilitys[i].value;
diff --git a/lib/log/meson.build b/lib/log/meson.build
index 4ac232786e..86e4452b19 100644
--- a/lib/log/meson.build
+++ b/lib/log/meson.build
@@ -11,4 +11,8 @@ if not is_windows
     sources += files('log_syslog.c')
 endif

+if is_linux
+    sources += files('log_journal.c')
+endif
+
 headers = files('rte_log.h')
diff --git a/lib/log/version.map b/lib/log/version.map
index 8be6907840..800d3943bc 100644
--- a/lib/log/version.map
+++ b/lib/log/version.map
@@ -26,6 +26,7 @@ INTERNAL {
        global:

        eal_log_init;
+       eal_log_journal; # WINDOWS_NO_EXPORT
        eal_log_level2str;
        eal_log_save_pattern;
        eal_log_save_regexp;
--
2.45.2



--
Baruch Even
Platform Technical Lead at WEKA
baruch@weka.io ­https://www.weka.io ­

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