[tarantool-patches] [PATCH v4 0/4] Syslog destination

[tarantool-patches] [PATCH v4 0/4] Syslog destination

[Olga Arkhangelskaia]

This series adds support of configurable destionation for syslog.
The option is called server. Possible options are ip4 and unix socket:
syslog:server=unix:/path/to/socket,identity=myinstance
syslog:server=ip4:port,identity=tarantool_myinstance

If server option is not set, but syslog is used in log configuration - 
default sockets for syslogd are used: /dev/log or /var/run/syslog.

Olga Arkhangelskaia (4):
  Configurable syslog destination
  box-tap: test valid log configuration
  box-tap: syslog destination test unix socket
  box-tap:syslog remote destination test

 src/say.c                 | 103 +++++++++++++++++++++++++++++++++++++++++++---
 src/say.h                 |  13 +++++-
 test/box-tap/cfg.test.lua |  73 +++++++++++++++++++++++++++++++-
 3 files changed, 182 insertions(+), 7 deletions(-)

--
https://github.com/tarantool/tarantool/issues/3487
https://github.com/tarantool/tarantool/tree/OKriw/gh-3487-syslog-conf-dest

v1:
https://www.freelists.org/post/tarantool-patches/PATCH-03-Syslog-destination

v2:
https://www.freelists.org/post/tarantool-patches/PATCH-v2-03-Syslog-destination

v3:
https://www.freelists.org/post/tarantool-patches/PATCH-v3-04-Syslog-destination

Changes in v2:
- Changed tests. Use random port, no sever is started, used current dir
- Changed basic structs - now we have emum for syslog dst, reuse log->pathi

Changes in v3:
- moved test to box-tap
- used pcall in case of stopped/unconfigured syslogd
- added syslog check syslog configuration test 

Changes in v4:
- fixed memory leak
- changed variables name
- removed unnecessary libs in tests
- removed pcall
- fixed identation   
2.14.3 (Apple Git-98)

[tarantool-patches] [PATCH v4 1/4] Configurable syslog destination

[Olga Arkhangelskaia]

Added server option to syslog configuration.
Server option is responsible for log destination. At the momemt
there is two ways of usage:server=unix:/path/to/socket or
server=ipv4:port. If port is not set default udp port 514 is used.
If logging to syslog is set, however there is no sever options -
default location is used: Linux /dev/log and Mac /var/run/syslog.

Closes #3487
---
 src/say.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 src/say.h |  13 +++++++-
 2 files changed, 110 insertions(+), 6 deletions(-)

diff --git a/src/say.c b/src/say.c
index ac221dd19..526b8862f 100644
--- a/src/say.c
+++ b/src/say.c
@@ -36,6 +36,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
+#include <netdb.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <fcntl.h>
@@ -45,6 +46,7 @@
 #include <arpa/inet.h>
 #include <coio_task.h>
 
+#define DEFAULT_PORT 514
 pid_t log_pid = 0;
 int log_level = S_INFO;
 enum say_format log_format = SF_PLAIN;
@@ -473,16 +475,85 @@ syslog_connect_unix(const char *path)
 	return fd;
 }
 
+/**
+ * Connect to remote syslogd using server:port.
+ * @param server address string of remote host.
+ * @retval not 0 Socket descriptor.
+ * @retval    -1 Socket error.
+ */
+static int
+syslog_connect_remote(const char *server_address)
+{
+	struct addrinfo *inf, hints, *ptr;
+	const char *remote;
+	char buf[10];
+	char *portnum, *copy;
+	int fd = -1;
+
+	copy = strdup(server_address);
+	if (copy == NULL) {
+		diag_set(OutOfMemory, strlen(server_address), "malloc",
+			 "stslog server address");
+		return fd;
+	}
+	portnum = copy;
+	remote = strsep(&portnum, ":");
+	if (portnum == NULL) {
+		snprintf(buf, sizeof(buf), "%d", DEFAULT_PORT);
+		portnum = buf;
+	}
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_INET;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_protocol = IPPROTO_UDP;
+
+	if (getaddrinfo(remote, (const char*)portnum, NULL, &inf) < 0) {
+		diag_set(SystemError, "syslog: getaddrinfo failed %s",
+			 gai_strerror(errno));
+		goto out;
+	}
+	for (ptr = inf; ptr; ptr = ptr->ai_next) {
+		fd = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
+		if (fd < 0) {
+			diag_set(SystemError, "syslog: socket failed %s",
+				 strerror(errno));
+			continue;
+		}
+		if (connect(fd, inf->ai_addr, inf->ai_addrlen) != 0) {
+			close(fd);
+			fd = -1;
+			diag_set(SystemError, "syslog:connect failed %s",
+				 strerror(errno));
+			continue;
+		}
+		break;
+	}
+	freeaddrinfo(inf);
+out:
+	free(copy);
+	return fd;
+}
+
 static inline int
 log_syslog_connect(struct log *log)
 {
 	/*
-	 * Try two locations: '/dev/log' for Linux and
+	 * If server option is not set use '/dev/log' for Linux and
 	 * '/var/run/syslog' for Mac.
 	 */
-	log->fd = syslog_connect_unix("/dev/log");
-	if (log->fd < 0)
-		log->fd = syslog_connect_unix("/var/run/syslog");
+	switch (log->server_type) {
+	case SAY_SYSLOG_UNIX:
+		log->fd = syslog_connect_unix(log->path);
+		break;
+	case SAY_SYSLOG_REMOTE:
+		log->fd = syslog_connect_remote(log->path);
+		break;
+	default:
+		log->fd = syslog_connect_unix("/dev/log");
+		if (log->fd < 0)
+			log->fd = syslog_connect_unix("/var/run/syslog");
+
+	}
 	return log->fd;
 }
 
@@ -498,6 +569,15 @@ log_syslog_init(struct log *log, const char *init_str)
 	if (say_parse_syslog_opts(init_str, &opts) < 0)
 		return -1;
 
+	log->server_type = opts.server_type;
+	if (log->server_type != SAY_SYSLOG_DEFAULT) {
+		log->path = strdup(opts.server_path);
+		if (log->path == NULL) {
+			diag_set(OutOfMemory, strlen(opts.server_path),
+				 "malloc", "server address");
+			return -1;
+		}
+	}
 	if (opts.identity == NULL)
 		log->syslog_ident = strdup("tarantool");
 	else
@@ -1031,6 +1111,8 @@ say_syslog_facility_by_name(const char *facility)
 int
 say_parse_syslog_opts(const char *init_str, struct say_syslog_opts *opts)
 {
+	opts->server_path = NULL;
+	opts->server_type = SAY_SYSLOG_DEFAULT;
 	opts->identity = NULL;
 	opts->facility = syslog_facility_MAX;
 	opts->copy = strdup(init_str);
@@ -1047,7 +1129,18 @@ say_parse_syslog_opts(const char *init_str, struct say_syslog_opts *opts)
 			break;
 
 		value = option;
-		if (say_parse_prefix(&value, "identity=")) {
+		if (say_parse_prefix(&value, "server=")) {
+			if (opts->server_path != NULL ||
+			    opts->server_type != SAY_SYSLOG_DEFAULT)
+				goto duplicate;
+			if (say_parse_prefix(&value, "unix:")) {
+				opts->server_type = SAY_SYSLOG_UNIX;
+				opts->server_path = value;
+			} else {
+				opts->server_type = SAY_SYSLOG_REMOTE;
+				opts->server_path = value;
+			}
+		} else if (say_parse_prefix(&value, "identity=")) {
 			if (opts->identity != NULL)
 				goto duplicate;
 			opts->identity = value;
diff --git a/src/say.h b/src/say.h
index 2c2395fe0..73697b1b7 100644
--- a/src/say.h
+++ b/src/say.h
@@ -79,6 +79,12 @@ say_log_level_is_enabled(int level)
 
 extern enum say_format log_format;
 
+enum say_logger_syslog_server {
+	SAY_SYSLOG_DEFAULT,
+	SAY_SYSLOG_UNIX,
+	SAY_SYSLOG_REMOTE
+};
+
 enum say_logger_type {
 	/**
 	 * Before the app server core is initialized, we do not
@@ -141,7 +147,10 @@ struct log {
 	/** The current log level. */
 	int level;
 	enum say_logger_type type;
-	/** path to file if logging to file. */
+	enum say_logger_syslog_server server_type;
+	/** Path to file if logging to file, socket
+	 *  or server address in case of syslog.
+	 */
 	char *path;
 	bool nonblock;
 	log_format_func_t format_func;
@@ -384,6 +393,8 @@ say_parse_logger_type(const char **str, enum say_logger_type *type);
 
 /** Syslog logger initialization params */
 struct say_syslog_opts {
+	enum say_logger_syslog_server server_type;
+	const char *server_path;
 	const char *identity;
 	enum syslog_facility facility;
 	/* Input copy (content unspecified). */
-- 
2.14.3 (Apple Git-98)

[tarantool-patches] [PATCH v4 2/4] box-tap: test valid log configuration

[Olga Arkhangelskaia]

Test case checks that valid log configuration is not broken,
as it happened in #3487
---
 test/box-tap/cfg.test.lua | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
index ffafdbe42..67e4c3af9 100755
--- a/test/box-tap/cfg.test.lua
+++ b/test/box-tap/cfg.test.lua
@@ -6,7 +6,7 @@ local socket = require('socket')
 local fio = require('fio')
 local uuid = require('uuid')
 local msgpack = require('msgpack')
-test:plan(95)
+test:plan(96)
 
 --------------------------------------------------------------------------------
 -- Invalid values
@@ -464,5 +464,13 @@ code = string.format(code_fmt, dir, instance_uuid, uuid.new())
 test:is(run_script(code), PANIC, "replicaset_uuid mismatch")
 fio.rmdir(dir)
 
+--
+-- Check syslog configuration
+-- (syslog daemon may be not started hence use pcall)
+--
+code = [[pcall(box.cfg, {log = 'syslog:identity=tarantool'})
+]]
+test:is(run_script(code), 0, "syslog log configuration")
+
 test:check()
 os.exit(0)
-- 
2.14.3 (Apple Git-98)

[tarantool-patches] [PATCH v4 3/4] box-tap: syslog destination test unix socket

[Olga Arkhangelskaia]

Adds syslog destination unix test in box-tap.
Test redirects logs to newly created unix socket and sets appropriate
log level. If log receives the same level - test passes. In case if
syslog is not configured we use pcall.

Closes #3487
---
 test/box-tap/cfg.test.lua | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
index 67e4c3af9..2b1769395 100755
--- a/test/box-tap/cfg.test.lua
+++ b/test/box-tap/cfg.test.lua
@@ -6,7 +6,7 @@ local socket = require('socket')
 local fio = require('fio')
 local uuid = require('uuid')
 local msgpack = require('msgpack')
-test:plan(96)
+test:plan(97)
 
 --------------------------------------------------------------------------------
 -- Invalid values
@@ -472,5 +472,32 @@ code = [[pcall(box.cfg, {log = 'syslog:identity=tarantool'})
 ]]
 test:is(run_script(code), 0, "syslog log configuration")
 
+--
+-- Check syslog socket configuration
+--
+code = [[
+local socket = require('socket')
+local log = require('log')
+local fio = require('fio')
+
+path = fio.pathjoin(fio.cwd(), 'log_unix_socket_test.sock')
+unix_socket = socket('AF_UNIX', 'SOCK_DGRAM', 0)
+unix_socket:bind('unix/', path)
+
+opt = string.format("syslog:server=unix:%s,identity=tarantool", path)
+res = 1
+box.cfg{log = opt, log_level = 5}
+log.info("Test socket syslog destination")
+buf = unix_socket:read("Test socket syslog destination", 30)
+if buf ~= nil then
+    if buf:match('Test socket syslog destination') then res = 0 end
+end
+
+unix_socket:close()                                                         
+os.remove(path) 
+os.exit(res)
+]]
+test:is(run_script(code), 0, "unix socket syslog log configuration")
+
 test:check()
 os.exit(0)
-- 
2.14.3 (Apple Git-98)

[tarantool-patches] [PATCH v4 4/4] box-tap:syslog remote destination test

[Olga Arkhangelskaia]

Adds syslog remote destination test in box-tap.
Test creates server, sets appropriate log level and redirects logs
to it. If log level received by the server is the same - test passes.
If syslogd is not running we use pcall.

Closes #3487
---
 test/box-tap/cfg.test.lua | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
index 2b1769395..34a6eaa66 100755
--- a/test/box-tap/cfg.test.lua
+++ b/test/box-tap/cfg.test.lua
@@ -6,7 +6,7 @@ local socket = require('socket')
 local fio = require('fio')
 local uuid = require('uuid')
 local msgpack = require('msgpack')
-test:plan(97)
+test:plan(98)
 
 --------------------------------------------------------------------------------
 -- Invalid values
@@ -499,5 +499,41 @@ os.exit(res)
 ]]
 test:is(run_script(code), 0, "unix socket syslog log configuration")
 
+--
+-- Check syslog remote configuration
+--
+code = [[
+local socket = require('socket')
+local log = require('log')
+
+addr = '127.0.0.1'
+port = 1000 + math.random(32768)
+
+sc = socket('AF_INET', 'SOCK_DGRAM', 'udp')
+local attempt = 0
+while attempt < 10 do
+    if not sc:bind (addr, port) then
+        port = 1000 + math.random(32768)
+        attempt = attempt + 1
+    else
+	break
+    end
+end
+sc:bind(addr, port)
+
+local opt = string.format("syslog:server=%s:%u,identity=tarantool", addr, port)
+local res = 1
+box.cfg{log = opt, log_level = 5}
+log.info('Test syslog destination')
+while (sc:readable(1)) do
+    buf = sc:recv(1000)
+    if buf:match('Test syslog destination') then res = 0 end
+end
+
+sc:close()
+os.exit(res)
+]]
+test:is(run_script(code), 0, "remote syslog log configuration")
+
 test:check()
 os.exit(0)
-- 
2.14.3 (Apple Git-98)

Re: [tarantool-patches] [PATCH v4 1/4] Configurable syslog destination

[Vladimir Davydov]

On Tue, Jul 31, 2018 at 01:18:30PM +0300, Olga Arkhangelskaia wrote:
> Added server option to syslog configuration.
> Server option is responsible for log destination. At the momemt
> there is two ways of usage:server=unix:/path/to/socket or
> server=ipv4:port. If port is not set default udp port 514 is used.
> If logging to syslog is set, however there is no sever options -
> default location is used: Linux /dev/log and Mac /var/run/syslog.
> 
> Closes #3487
> ---
>  src/say.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  src/say.h |  13 +++++++-
>  2 files changed, 110 insertions(+), 6 deletions(-)
> 
> diff --git a/src/say.c b/src/say.c
> index ac221dd19..526b8862f 100644
> --- a/src/say.c
> +++ b/src/say.c
> @@ -45,6 +46,7 @@
>  #include <arpa/inet.h>
>  #include <coio_task.h>
>  
> +#define DEFAULT_PORT 514

We don't use macros when we can define a constant in a enum, e.g.

	enum { DEFAULT_PORT = 512 };

Also, DEFAULT_PORT is a too generic name. I think you should prefix it
with SAY_SYSLOG_.

>  pid_t log_pid = 0;
>  int log_level = S_INFO;
>  enum say_format log_format = SF_PLAIN;
> @@ -473,16 +475,85 @@ syslog_connect_unix(const char *path)
>  	return fd;
>  }
>  
> +/**
> + * Connect to remote syslogd using server:port.
> + * @param server address string of remote host.

_ is missing between 'server' and 'address'.

> + * @retval not 0 Socket descriptor.
> + * @retval    -1 Socket error.
> + */
> +static int
> +syslog_connect_remote(const char *server_address)
> +{
> +	struct addrinfo *inf, hints, *ptr;
> +	const char *remote;
> +	char buf[10];
> +	char *portnum, *copy;
> +	int fd = -1;
> +
> +	copy = strdup(server_address);
> +	if (copy == NULL) {
> +		diag_set(OutOfMemory, strlen(server_address), "malloc",
> +			 "stslog server address");
> +		return fd;
> +	}
> +	portnum = copy;
> +	remote = strsep(&portnum, ":");
> +	if (portnum == NULL) {
> +		snprintf(buf, sizeof(buf), "%d", DEFAULT_PORT);
> +		portnum = buf;
> +	}
> +	memset(&hints, 0, sizeof(hints));
> +	hints.ai_family = AF_INET;
> +	hints.ai_socktype = SOCK_DGRAM;
> +	hints.ai_protocol = IPPROTO_UDP;
> +
> +	if (getaddrinfo(remote, (const char*)portnum, NULL, &inf) < 0) {
> +		diag_set(SystemError, "syslog: getaddrinfo failed %s",
> +			 gai_strerror(errno));

First, getaddrinfo() doesn't set errno. You are supposed to call
gai_strerror() on the code it returned.

Second, SystemError always appends strerror(errno) to the error message.
Since getaddrinfo() doesn't do that, you should set errno manually. EIO
seems to be a good choice. Take a look at coio_getaddrinfo() for an
example.

Third, there's no point to prepend the error message with "syslog:".
diag_set() includes file name and string to the error message so finding
a culprit shouldn't be a problem.

> +		goto out;
> +	}
> +	for (ptr = inf; ptr; ptr = ptr->ai_next) {
> +		fd = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
> +		if (fd < 0) {
> +			diag_set(SystemError, "syslog: socket failed %s",
> +				 strerror(errno));

Again. No point to prepend "syslog:" and append strerror(errno).

> +			continue;
> +		}
> +		if (connect(fd, inf->ai_addr, inf->ai_addrlen) != 0) {
> +			close(fd);
> +			fd = -1;
> +			diag_set(SystemError, "syslog:connect failed %s",
> +				 strerror(errno));

Ditto.

> +			continue;
> +		}
> +		break;
> +	}
> +	freeaddrinfo(inf);
> +out:
> +	free(copy);
> +	return fd;
> +}

> diff --git a/src/say.h b/src/say.h
> index 2c2395fe0..73697b1b7 100644
> --- a/src/say.h
> +++ b/src/say.h
> @@ -79,6 +79,12 @@ say_log_level_is_enabled(int level)
>  
>  extern enum say_format log_format;
>  
> +enum say_logger_syslog_server {

Let's rename this to say_syslog_server_type?

> +	SAY_SYSLOG_DEFAULT,
> +	SAY_SYSLOG_UNIX,
> +	SAY_SYSLOG_REMOTE
> +};
> +
>  enum say_logger_type {
>  	/**
>  	 * Before the app server core is initialized, we do not
> @@ -141,7 +147,10 @@ struct log {
>  	/** The current log level. */
>  	int level;
>  	enum say_logger_type type;
> -	/** path to file if logging to file. */
> +	enum say_logger_syslog_server server_type;

Missing comment to 'server_type'. Also, let's prefix it with 'syslog_',
like other syslog-related options (syslog_identity, syslog_facility).

> +	/** Path to file if logging to file, socket
> +	 *  or server address in case of syslog.
> +	 */

/**
 * Malformed comment format.
 * Multi-line comments should look like this.
 */

Re: [tarantool-patches] [PATCH v4 3/4] box-tap: syslog destination test unix socket

[Vladimir Davydov]

We don't submit tests accompanying a feature in separate patches unless
there's a reason to do that. Please fold patches 3 and 4 in patch 1.

On Tue, Jul 31, 2018 at 01:18:32PM +0300, Olga Arkhangelskaia wrote:
> Adds syslog destination unix test in box-tap.
> Test redirects logs to newly created unix socket and sets appropriate
> log level. If log receives the same level - test passes. In case if
> syslog is not configured we use pcall.
> 
> Closes #3487
> ---
>  test/box-tap/cfg.test.lua | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
> index 67e4c3af9..2b1769395 100755
> --- a/test/box-tap/cfg.test.lua
> +++ b/test/box-tap/cfg.test.lua
> @@ -6,7 +6,7 @@ local socket = require('socket')
>  local fio = require('fio')
>  local uuid = require('uuid')
>  local msgpack = require('msgpack')
> -test:plan(96)
> +test:plan(97)
>  
>  --------------------------------------------------------------------------------
>  -- Invalid values
> @@ -472,5 +472,32 @@ code = [[pcall(box.cfg, {log = 'syslog:identity=tarantool'})
>  ]]
>  test:is(run_script(code), 0, "syslog log configuration")
>  
> +--
> +-- Check syslog socket configuration
> +--

s/socket/unix socket

Also, we usually mention GitHub ticket in the comment to a test case,
e.g. gh-3487.

> +code = [[
> +local socket = require('socket')
> +local log = require('log')
> +local fio = require('fio')
> +
> +path = fio.pathjoin(fio.cwd(), 'log_unix_socket_test.sock')
> +unix_socket = socket('AF_UNIX', 'SOCK_DGRAM', 0)
> +unix_socket:bind('unix/', path)
> +
> +opt = string.format("syslog:server=unix:%s,identity=tarantool", path)
> +res = 1
> +box.cfg{log = opt, log_level = 5}
> +log.info("Test socket syslog destination")
> +buf = unix_socket:read("Test socket syslog destination", 30)
> +if buf ~= nil then
> +    if buf:match('Test socket syslog destination') then res = 0 end
> +end

I don't like that you use such a long string as a delimiter (first
argument of 'read' is delimiter, right?). It looks weird. Why not
rewrite the code exactly in the way you use for testing udp syslog
destination?

> +
> +unix_socket:close()                                                         
> +os.remove(path) 
> +os.exit(res)
> +]]
> +test:is(run_script(code), 0, "unix socket syslog log configuration")
> +
>  test:check()
>  os.exit(0)

Re: [tarantool-patches] [PATCH v4 4/4] box-tap:syslog remote destination test

[Vladimir Davydov]

On Tue, Jul 31, 2018 at 01:18:33PM +0300, Olga Arkhangelskaia wrote:
> Adds syslog remote destination test in box-tap.
> Test creates server, sets appropriate log level and redirects logs
> to it. If log level received by the server is the same - test passes.
> If syslogd is not running we use pcall.
> 
> Closes #3487
> ---
>  test/box-tap/cfg.test.lua | 38 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/test/box-tap/cfg.test.lua b/test/box-tap/cfg.test.lua
> index 2b1769395..34a6eaa66 100755
> --- a/test/box-tap/cfg.test.lua
> +++ b/test/box-tap/cfg.test.lua
> @@ -6,7 +6,7 @@ local socket = require('socket')
>  local fio = require('fio')
>  local uuid = require('uuid')
>  local msgpack = require('msgpack')
> -test:plan(97)
> +test:plan(98)
>  
>  --------------------------------------------------------------------------------
>  -- Invalid values
> @@ -499,5 +499,41 @@ os.exit(res)
>  ]]
>  test:is(run_script(code), 0, "unix socket syslog log configuration")
>  
> +--
> +-- Check syslog remote configuration
> +--
> +code = [[
> +local socket = require('socket')
> +local log = require('log')
> +
> +addr = '127.0.0.1'
> +port = 1000 + math.random(32768)
> +
> +sc = socket('AF_INET', 'SOCK_DGRAM', 'udp')
> +local attempt = 0
> +while attempt < 10 do
> +    if not sc:bind (addr, port) then
> +        port = 1000 + math.random(32768)
> +        attempt = attempt + 1
> +    else
> +	break

A tab instead of spaces. Please fix indentation.

> +    end
> +end
> +sc:bind(addr, port)
> +
> +local opt = string.format("syslog:server=%s:%u,identity=tarantool", addr, port)
> +local res = 1
> +box.cfg{log = opt, log_level = 5}
> +log.info('Test syslog destination')
> +while (sc:readable(1)) do

The parentheses are redundant.

> +    buf = sc:recv(1000)

I think that a message can get split (at least, theoretically).
Shouldn't you append the result to the buffer instead:

	buf = buf .. sc:recv(1000)

> +    if buf:match('Test syslog destination') then res = 0 end
> +end
> +
> +sc:close()
> +os.exit(res)
> +]]
> +test:is(run_script(code), 0, "remote syslog log configuration")
> +
>  test:check()
>  os.exit(0)