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HAProxy TCP log format (1.7)
8.2.2. TCP log format
---------------------
The TCP format is used when "option tcplog" is specified in the frontend, and
is the recommended format for pure TCP proxies. It provides a lot of precious
information for troubleshooting. Since this format includes timers and byte
counts, the log is normally emitted at the end of the session. It can be
emitted earlier if "option logasap" is specified, which makes sense in most
environments with long sessions such as remote terminals. Sessions which match
the "monitor" rules are never logged. It is also possible not to emit logs for
sessions for which no data were exchanged between the client and the server, by
specifying "option dontlognull" in the frontend. Successful connections will
not be logged if "option dontlog-normal" is specified in the frontend. A few
fields may slightly vary depending on some configuration options, those are
marked with a star ('*') after the field name below.
Example :
frontend fnt
mode tcp
option tcplog
log global
default_backend bck
backend bck
server srv1 127.0.0.1:8000
>>> Feb 6 12:12:56 localhost \
haproxy[14387]: 10.0.1.2:33313 [06/Feb/2009:12:12:51.443] fnt \
bck/srv1 0/0/5007 212 -- 0/0/0/0/3 0/0
Field Format Extract from the example above
1 process_name '[' pid ']:' haproxy[14387]:
2 client_ip ':' client_port 10.0.1.2:33313
3 '[' accept_date ']' [06/Feb/2009:12:12:51.443]
4 frontend_name fnt
5 backend_name '/' server_name bck/srv1
6 Tw '/' Tc '/' Tt* 0/0/5007
7 bytes_read* 212
8 termination_state --
9 actconn '/' feconn '/' beconn '/' srv_conn '/' retries* 0/0/0/0/3
10 srv_queue '/' backend_queue 0/0
Detailed fields description :
- "client_ip" is the IP address of the client which initiated the TCP
connection to haproxy. If the connection was accepted on a UNIX socket
instead, the IP address would be replaced with the word "unix". Note that
when the connection is accepted on a socket configured with "accept-proxy"
and the PROXY protocol is correctly used, or with a "accept-netscaler-cip"
and the NetScaler Client IP insetion protocol is correctly used, then the
logs will reflect the forwarded connection's information.
- "client_port" is the TCP port of the client which initiated the connection.
If the connection was accepted on a UNIX socket instead, the port would be
replaced with the ID of the accepting socket, which is also reported in the
stats interface.
- "accept_date" is the exact date when the connection was received by haproxy
(which might be very slightly different from the date observed on the
network if there was some queuing in the system's backlog). This is usually
the same date which may appear in any upstream firewall's log.
- "frontend_name" is the name of the frontend (or listener) which received
and processed the connection.
- "backend_name" is the name of the backend (or listener) which was selected
to manage the connection to the server. This will be the same as the
frontend if no switching rule has been applied, which is common for TCP
applications.
- "server_name" is the name of the last server to which the connection was
sent, which might differ from the first one if there were connection errors
and a redispatch occurred. Note that this server belongs to the backend
which processed the request. If the connection was aborted before reaching
a server, "<NOSRV>" is indicated instead of a server name.
- "Tw" is the total time in milliseconds spent waiting in the various queues.
It can be "-1" if the connection was aborted before reaching the queue.
See "Timers" below for more details.
- "Tc" is the total time in milliseconds spent waiting for the connection to
establish to the final server, including retries. It can be "-1" if the
connection was aborted before a connection could be established. See
"Timers" below for more details.
- "Tt" is the total time in milliseconds elapsed between the accept and the
last close. It covers all possible processing. There is one exception, if
"option logasap" was specified, then the time counting stops at the moment
the log is emitted. In this case, a '+' sign is prepended before the value,
indicating that the final one will be larger. See "Timers" below for more
details.
- "bytes_read" is the total number of bytes transmitted from the server to
the client when the log is emitted. If "option logasap" is specified, the
this value will be prefixed with a '+' sign indicating that the final one
may be larger. Please note that this value is a 64-bit counter, so log
analysis tools must be able to handle it without overflowing.
- "termination_state" is the condition the session was in when the session
ended. This indicates the session state, which side caused the end of
session to happen, and for what reason (timeout, error, ...). The normal
flags should be "--", indicating the session was closed by either end with
no data remaining in buffers. See below "Session state at disconnection"
for more details.
- "actconn" is the total number of concurrent connections on the process when
the session was logged. It is useful to detect when some per-process system
limits have been reached. For instance, if actconn is close to 512 when
multiple connection errors occur, chances are high that the system limits
the process to use a maximum of 1024 file descriptors and that all of them
are used. See section 3 "Global parameters" to find how to tune the system.
- "feconn" is the total number of concurrent connections on the frontend when
the session was logged. It is useful to estimate the amount of resource
required to sustain high loads, and to detect when the frontend's "maxconn"
has been reached. Most often when this value increases by huge jumps, it is
because there is congestion on the backend servers, but sometimes it can be
caused by a denial of service attack.
- "beconn" is the total number of concurrent connections handled by the
backend when the session was logged. It includes the total number of
concurrent connections active on servers as well as the number of
connections pending in queues. It is useful to estimate the amount of
additional servers needed to support high loads for a given application.
Most often when this value increases by huge jumps, it is because there is
congestion on the backend servers, but sometimes it can be caused by a
denial of service attack.
- "srv_conn" is the total number of concurrent connections still active on
the server when the session was logged. It can never exceed the server's
configured "maxconn" parameter. If this value is very often close or equal
to the server's "maxconn", it means that traffic regulation is involved a
lot, meaning that either the server's maxconn value is too low, or that
there aren't enough servers to process the load with an optimal response
time. When only one of the server's "srv_conn" is high, it usually means
that this server has some trouble causing the connections to take longer to
be processed than on other servers.
- "retries" is the number of connection retries experienced by this session
when trying to connect to the server. It must normally be zero, unless a
server is being stopped at the same moment the connection was attempted.
Frequent retries generally indicate either a network problem between
haproxy and the server, or a misconfigured system backlog on the server
preventing new connections from being queued. This field may optionally be
prefixed with a '+' sign, indicating that the session has experienced a
redispatch after the maximal retry count has been reached on the initial
server. In this case, the server name appearing in the log is the one the
connection was redispatched to, and not the first one, though both may
sometimes be the same in case of hashing for instance. So as a general rule
of thumb, when a '+' is present in front of the retry count, this count
should not be attributed to the logged server.
- "srv_queue" is the total number of requests which were processed before
this one in the server queue. It is zero when the request has not gone
through the server queue. It makes it possible to estimate the approximate
server's response time by dividing the time spent in queue by the number of
requests in the queue. It is worth noting that if a session experiences a
redispatch and passes through two server queues, their positions will be
cumulated. A request should not pass through both the server queue and the
backend queue unless a redispatch occurs.
- "backend_queue" is the total number of requests which were processed before
this one in the backend's global queue. It is zero when the request has not
gone through the global queue. It makes it possible to estimate the average
queue length, which easily translates into a number of missing servers when
divided by a server's "maxconn" parameter. It is worth noting that if a
session experiences a redispatch, it may pass twice in the backend's queue,
and then both positions will be cumulated. A request should not pass
through both the server queue and the backend queue unless a redispatch
occurs.
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