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syslog-ng Premium Edition 6.0.21 - Administration Guide

Preface Chapter 1. Introduction to syslog-ng Chapter 2. The concepts of syslog-ng Chapter 3. Installing syslog-ng Chapter 4. The syslog-ng PE quick-start guide Chapter 5. The syslog-ng PE configuration file Chapter 6. Collecting log messages — sources and source drivers Chapter 7. Sending and storing log messages — destinations and destination drivers Chapter 8. Routing messages: log paths, reliability, and filters Chapter 9. Global options of syslog-ng PE Chapter 10. TLS-encrypted message transfer Chapter 12.  Reliable Log Transfer Protocol™ Chapter 13. Reliability and minimizing the loss of log messages Chapter 14. Manipulating messages Chapter 15. Parsing and segmenting structured messages Chapter 16. Processing message content with a pattern database Chapter 17. Statistics and metrics of syslog-ng Chapter 18. Multithreading and scaling in syslog-ng PE Chapter 19. Troubleshooting syslog-ng Chapter 20. Best practices and examples

Storing messages in an SQL database

The sql() driver sends messages into an SQL database. Currently the Microsoft SQL (MSSQL), MySQL, Oracle, PostgreSQL, and SQLite databases are supported.

NOTE:

In order to use this destination, syslog-ng Premium Edition must run in server mode. Typically, only the central syslog-ng Premium Edition server uses this destination. For details on the server mode, see the section called “Server mode”.

Declaration: 

sql(database_type host_parameters database_parameters [options]);

The sql() driver has the following required parameters: type(), database(), table(), columns(), and values().

Caution:

The syslog-ng application requires read and write access to the SQL table, otherwise it cannot verify that the destination table exists.

Currently the syslog-ng application has default schemas for the different databases and uses these defaults if the database schema (for example columns and column types) is not defined in the configuration file. However, these schemas will be deprecated and specifying the exact database schema will be required in later versions of syslog-ng.

NOTE:

In addition to the standard syslog-ng packages, the sql() destination requires database-specific packages to be installed. These packages are automatically installed by the binary syslog-ng installer.

The sql() driver is currently not available for every platform that is supported by syslog-ng. For a list of platforms that support the sql() driver, visit this link.

The table and value parameters can include macros to create tables and columns dynamically (for details, see the section called “Macros of syslog-ng PE”).

Caution:

When using macros in table names, note that some databases limit the maximum allowed length of table names. Consult the documentation of the database for details.

Inserting the records into the database is performed by a separate thread. The syslog-ng application automatically performs the escaping required to insert the messages into the database.

Example 7.34. Using the sql() driver

The following example sends the log messages into a PostgreSQL database running on the logserver host. The messages are inserted into the logs database, the name of the table includes the exact date and the name of the host sending the messages. The syslog-ng application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

destination d_sql {
  sql(type(pgsql)
  host("logserver") username("syslog-ng") password("password")
  database("logs")
  table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
  columns("datetime", "host", "program", "pid", "message")
  values("{$R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid", "message"));
};

The following example specifies the type of the database columns as well:

destination d_sql {
  sql(type(pgsql)
  host("logserver") username("syslog-ng") password("password")
  database("logs")
  table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
  columns("datetime varchar(16)", "host varchar(32)", "program  varchar(20)", "pid varchar(8)", "message  varchar(200)")
  values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid", "message"));
};

Using the sql() driver with an Oracle database

The Oracle sql destination has some special aspects that are important to note.

  • The hostname of the database server is set in the tnsnames.ora file, not in the host parameter of the sql() destination.

    If the tnsnames.ora file is not located in the /etc directory (or in the /var/opt/oracle directory on Solaris), set the following Oracle-related environment variables, so syslog-ng PE will find the file: ORACLE_BASE, ORACLE_HOME, and ORACLE_SID. For details, see the documentation of the Oracle Instant Client.

  • You cannot use the same database() settings in more than one destination, because the database() option of the SQL driver is just a reference to the connection string of the tnsnames.ora file. To overcome this problem, you can duplicate the connections in the tnsnames.ora file under a different name, and use a different table in each Oracle destination in syslog-ng PE.

  • As certain database versions limit the maximum length of table names, macros in the table names should be used with care.

  • In the current version of syslog-ng PE, the types of database columns must be explicitly set for the Oracle destination. The column used to store the text part of the syslog messages should be able to store messages as long as the longest message permitted by syslog-ng, therefore it is usually recommended to use the varchar2 or clob column type. (The maximum length of the messages can be set using the log-msg-size() option.) For details, see the following example.

  • The Oracle Instant Client used by syslog-ng PE supports only the following character sets:

    • Single-byte character sets: US7ASCII, WE8DEC, WE8MSWIN1252, and WE8ISO8859P1

    • Unicode character sets: UTF8, AL16UTF16, and AL32UTF8

Example 7.35. Using the sql() driver with an Oracle database

The following example sends the log messages into an Oracle database running on the logserver host, which must be set in the /etc/tnsnames.ora file. The messages are inserted into the LOGS database, the name of the table includes the exact date when the messages were sent. The syslog-ng application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

destination d_sql {
  sql(type(oracle)
  username("syslog-ng") password("password")
  database("LOGS")
  table("msgs_${R_YEAR}${R_MONTH}${R_DAY}")
  columns("datetime varchar(16)", "host varchar(32)", "program varchar(32)", "pid varchar(8)", "message varchar2")
  values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid", "message"));
};

The Oracle Instant Client retrieves the address of the database server from the /etc/tnsnames.ora file. Edit or create this file as needed for your configuration. A sample is provided below.

LOGS =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)
(HOST = logserver)
(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = EXAMPLE.SERVICE)
)
)

Using the sql() driver with a Microsoft SQL database

The mssql database driver can access Microsoft SQL (MSSQL) destinations. This driver has some special aspects that are important to note.

  • The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. For details, see the following example.

  • As certain database versions limit the maximum length of table names, macros in the table names should be used with care.

  • In the current version of syslog-ng PE, the types of database columns must be explicitly set for the MSSQL destination.

    Caution:

    The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

  • The column used to store the text part of the syslog messages should be able to store messages as long as the longest message permitted by syslog-ng. The varchar column type can store maximum 4096 bytes-long messages. The maximum length of the messages can be set using the log-msg-size() option. For details, see the following example.

  • Remote access for SQL users must be explicitly enabled on the Microsoft Windows host running the Microsoft SQL Server. For details, see Procedure 3.12, “Configuring Microsoft SQL Server to accept logs from syslog-ng”.

Example 7.36. Using the sql() driver with an MSSQL database

The following example sends the log messages into an MSSQL database running on the logserver host. The messages are inserted into the syslogng database, the name of the table includes the exact date when the messages were sent. The syslog-ng application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

destination d_mssql {
sql(type(mssql) host("logserver") port("1433")
  username("syslogng") password("syslogng") database("syslogng")
  table("msgs_${R_YEAR}${R_MONTH}${R_DAY}")columns("datetime varchar(16)", "host varchar(32)",
  "program varchar(32)", "pid varchar(8)", "message varchar(4096)")
  values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid"));
};

The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. Edit or create this file as needed for your configuration. A sample is provided below.

[default]
date = "%Y-%m-%d %H:%M:%S"

The way syslog-ng interacts with the database

Used SQL operations by syslog-ng. 

Create table:

  • If the given table does not exist, syslog-ng tries to create it with the given column types.

  • The syslog-ng PE application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

  • If syslog-ng cannot create or alter a table, it tries to do it again when it reaches the next time-reopen().

Alter table:

  • If the table structure is different from given structure in an existing table, syslog-ng tries to add columns in this table but never will delete or modify an existing column.

  • If syslog-ng PE cannot create or alter a table, it tries to do it again when reach the next time-reopen().

  • The syslog-ng PE application requires read and write access to the SQL table, otherwise it cannot verify that the destination table exists.

Insert table:

  • Insert new records in a table.

  • Inserting the records into the database is performed by a separate thread.

  • The syslog-ng PE application automatically performs the escaping required to insert the messages into the database.

  • If insert returns with error, syslog-ng tries to insert the message +two times by default, then drops it. Retrying time is the value of time-reopen().

Encoding. 

The syslog-ng PE application uses UTF-8 by default when writes logs into database.

Start/stop and reload. 

Start:

  • The syslog-ng PE application will connect to database automatically after starting regardless existing incoming messages.

Stop:

  • The syslog-ng PE application will close the connection to database before shutting down.

Possibility of losing logs:

  • The syslog-ng PE application cannot lose logs during shutting down if disk buffer was given and it is not full yet.

  • The syslog-ng PE application cannot lose logs during shutting down if disk buffer was not given.

Reload:

  • The syslog-ng PE application will close the connection to database if it received SIGHUP signal (reload).

  • It will reconnect to the database when it tries to send a new message to this database again.

Macros: 

The value of ${SEQNUM} macro will be overrided by sql driver regardless of local or relayed incoming message.

It will be grown continously.

MySQL-specific interaction methods

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

MsSQL-specific interaction methods

In SQL Server 2005 this restriction is lifted - kind of. The total length of all key columns in an index cannot exceed 900 bytes.

If you are using null() in your configuration, be sure that the columns allow NULL to insert. Give the column as the following example: "datetime varchar(16) NULL".

The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. [default] date = "%Y-%m-%d %H:%M:%S".

Supported SQL destinations by platform

Table 7.2. Supported SQL destinations by platform

Platform \ Database MSSQL MySQL PgSQL SQLite Oracle
AIX -
Linux (linux_glibc236): CentOS 5
Linux (linux_glibc236): CentOS 6
Linux (linux_glibc236): CentOS 7
Linux (linux_glibc236): Debian 7
Linux (linux_glibc236): openSUSE 11
Linux (linux_glibc236): Oracle Linux 5
Linux (linux_glibc236): Oracle Linux 6
Linux (linux_glibc236): Oracle Linux 7
Linux (linux_glibc236): SLES 11
Linux (linux_glibc236): Red Hat EL 5
Linux (linux_glibc236): Red Hat EL 6
Linux (linux_glibc236): Red Hat EL 7
Linux (linux_glibc236): Ubuntu 12.04
Linux (linux_glibc236): Ubuntu 14.04
FreeBSD 8 -
FreeBSD 9 -
FreeBSD 10 -
HP-UX 11v2_on IA64 -
Solaris 10 on SPARC and SPARC64
Solaris 11 on SPARC and SPARC64
Solaris 10 on x86_64 -
Solaris 11 on x86_64 -

sql() destination options

NOTE:

In order to use this destination, syslog-ng Premium Edition must run in server mode. Typically, only the central syslog-ng Premium Edition server uses this destination. For details on the server mode, see the section called “Server mode”.

This driver sends messages into an SQL database. The sql() destination has the following options:

columns()
Type: string list
Default: "date", "facility", "level", "host", "program", "pid", "message"

Description: Name of the columns storing the data in fieldname [dbtype] format. The [dbtype] parameter is optional, and specifies the type of the field. By default, syslog-ng PE creates text columns. Note that not every database engine can index text fields.

Caution:

The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

database()
Type: string
Default: logs

Description: Name of the database that stores the logs. Macros cannot be used in database name. Also, when using an Oracle database, you cannot use the same database() settings in more than one destination.

disk-buffer()

Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

reliable()
Type: yes|no
Default: no

Description: If set to yes, syslog-ng PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.

Caution:

Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost.

dir()
Type: string
Default: N/A

Description: Defines the folder where the disk-buffer files are stored. This option has priority over --qdisk-dir=.

Caution:

When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file, or at least remove the relevant persist-entry.

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file or the relevant entry is not deleted after modifying the dir() option, then following a restart, syslog-ng PE will look for or create disk-buffer files in their old location. To ensure that syslog-ng PE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

disk-buf-size()
Type: number (bytes)
Default:
Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.
mem-buf-length()
Type: number (messages)
Default: 10000
Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.
mem-buf-size()
Type: number (bytes)
Default: 163840000
Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.
quot-size()
Type: number (messages)
Default: 64
Description: The number of messages stored in the output buffer of the destination.

Options reliable() and disk-buf-size() are required options.

Example 7.37. Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network(
            "127.0.0.1"
            port(3333)
            disk-buffer(
                mem-buf-size(10000)
                disk-buf-size(2000000)
                reliable(yes)
                dir("/tmp/disk-buffer")
            )
        );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network(
            "127.0.0.1"
            port(3333)
            disk-buffer(
                mem-buf-length(10000)
                disk-buf-size(2000000)
                reliable(no)
                dir("/tmp/disk-buffer")
            )
        );
};

flags()
Type: list of flags
Default: empty string

Description: Flags related to the sql() destination.

  • dont-create-tables: Enable this flag to prevent syslog-ng PE from creating non-existing database tables automatically. The syslog-ng PE application typically has to create tables if you use macros in the table names. Available in syslog-ng PE version 4.0 and later.

  • explicit-commits: By default, syslog-ng PE commits every log message to the target database individually. When the explicit-commits option is enabled, messages are committed in batches. This improves the performance, but results in some latency, as the messages are not immediately sent to the database. The size and frequency of batched commits can be set using the flush-lines() parameter. The explicit-commits option is available in syslog-ng PE version 4.0 and later.

Example 7.38. Setting flags for SQL destinations

The following example sets the dont-create-tables and explicit-commits flags for an sql() destination.

flags(dont-create-tables,explicit-commits)

flush-lines()
Type: number (messages)
Default: Use global setting.

Description: Specifies how many lines are sent to a destination at a time. The syslog-ng PE application waits for this number of lines to accumulate and sends them off in a single batch. Setting this number high increases throughput as fully filled frames are sent to the destination, but also increases message latency.

For optimal performance when sending messages to an syslog-ng PE server, make sure that the flush-lines() is smaller than the window size set using the log-iw-size() option in the source of your server.

flush-timeout() (OBSOLETE)
Type: time in milliseconds
Default: Use global setting.

Description: This is an obsolete option. Specifies the time syslog-ng waits for lines to accumulate in its output buffer. For details, see the flush-lines() option.

NOTE:

This option will be removed from the list of acceptable options. After that, your configuration will become invalid if it still contains the flush-timeout() option. To avoid future problems, remove this option from your configuration.

frac-digits()
Type: number (digits of fractions of a second)
Default: Value of the global option (which defaults to 0)

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

host()
Type: hostname or IP address
Default: n/a

Description: Hostname of the database server. Note that Oracle destinations do not use this parameter, but retrieve the hostname from the /etc/tnsnames.ora file.

NOTE:

If you specify host="localhost", syslog-ng will use a socket to connect to the local database server. Use host="127.0.0.1" to force TCP communication between syslog-ng and the local database server.

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

indexes()
Type: string list
Default: "date", "facility", "host", "program"

Description: The list of columns that are indexed by the database to speed up searching. To disable indexing for the destination, include the empty indexes() parameter in the destination, simply omitting the indexes parameter will cause syslog-ng to request indexing on the default columns.

The syslog-ng PE application will create the name of indexes automaticaly with the following method:

  • In case of MsSQL, PostgreSQL, MySQL or SQLite or (Oracle but tablename < 30 characters): {table}_{column}_idx.

  • In case of Oracle and tablename > 30 characters: md5sum of {table}_{column}-1 and the first character will be replaced by "i" character and the md5sum will be truncated to 30 characters.

local-time-zone()
Type: name of the timezone, or the timezone offset
Default: The local timezone.

Description: Sets the timezone used when expanding filename and tablename templates.

The timezone can be specified as using the name of the (for example time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

log-fifo-size()
Type: number (messages)
Default: Use global setting.

Description: The number of messages that the output queue can store.

null()
Type: string
Default:

Description: If the content of a column matches the string specified in the null() parameter, the contents of the column will be replaced with an SQL NULL value. If unset (by default), the option does not match on any string. For details, see the Example 7.39, “Using SQL NULL values”.

Example 7.39. Using SQL NULL values

The null() parameter of the SQL driver can be used to replace the contents of a column with a special SQL NULL value. To replace every column that contains an empty string with NULL, use the null("") option, for example

destination d_sql {
    sql(type(pgsql)
    host("logserver") username("syslog-ng") password("password")
    database("logs")
    table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
    columns("datetime", "host", "program", "pid", "message")
    values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
    indexes("datetime", "host", "program", "pid", "message")
    null(""));
};

To replace only a specific column (for example pid) if it is empty, assign a default value to the column, and use this default value in the null() parameter:

destination d_sql {
    sql(type(pgsql)
    host("logserver") username("syslog-ng") password("password")
    database("logs")
    table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
    columns("datetime", "host", "program", "pid", "message")
    values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID:-@@NULL@@}", "${MSGONLY}")
    indexes("datetime", "host", "program", "pid", "message")
    null("@@NULL@@"));
};

Ensure that the default value you use does not appear in the actual log messages, because other occurrences of this string will be replaced with NULL as well.


password()
Type: string
Default: n/a

Description: Password of the database user.

port()
Type: number (port number)
Default: 1433 TCP for MSSQL, 3306 TCP for MySQL, 1521 for Oracle, and 5432 TCP for PostgreSQL

Description: The port number to connect to.

retries

Type: number (insertion attempts)
Default: 3

Description: The number of insertion attempts. If syslog-ng PE could not insert a message into the database, it will repeat the attempt until the number of attempts reaches retries, then drops the connection to the database. For example, syslog-ng PE will try to insert a message maximum three times by default (once for first insertion and twice if the first insertion was failed).

session-statements()
Type: comma-separated list of SQL statements
Default: empty string

Description: Specifies one or more SQL-like statement which is executed after syslog-ng PE has successfully connected to the database. For example:

session-statements("SET COLLATION_CONNECTION='utf8_general_ci'")

Caution:

The syslog-ng PE application does not validate or limit the contents of customized queries. Consequently, queries performed with a user with write-access can potentially modify or even harm the database. Use customized queries with care, and only for your own responsibility.

table()
Type: string
Default: messages

Description: Name of the database table to use (can include macros). When using macros, note that some databases limit the length of table names.

time-zone()
Type: name of the timezone, or the timezone offset
Default: unspecified

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see the section called “Date-related macros”.

The timezone can be specified as using the name of the (for example time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

type()
Type: mssql, mysql, oracle, pgsql, or sqlite3
Default: mysql

Description: Specifies the type of the database, that is, the DBI database driver to use. Use the mssql option to send logs to an MSSQL database. For details, see the examples of the databases on the following sections.

username()
Type: string
Default: n/a

Description: Name of the database user.

values()
Type: string list
Default: "${R_YEAR}-${R_MONTH}-${R_DAY}, ${R_HOUR}:${R_MIN}:${R_SEC}", "${FACILITY}", "${LEVEL}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}"

Description: The parts of the message to store in the fields specified in the columns() parameter.

It is possible to give a special value calling: default (without quotation marks).It means that the value will be used that is the default of the column type of this value.

Example 7.40. Value: default

columns("date datetime", "host varchar(32)", "row_id serial")
values("${R_DATE}", "${HOST}", default)

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