The configuration file is in “ini” format. Section names are between “[” and “]”. Lines starting with “;” or “#” are taken as comments and ignored. The characters “;” and “#” are not recognized as special when they appear later in the line.
Specifies the log file. For daemonization (-d), either this or
syslog need to be set.
The log file is kept open, so after rotation, kill -HUP
or on console RELOAD; should be done.
On Windows, the service must be stopped and started.
Note that setting logfile does not by itself turn off logging to
stderr. Use the command-line option -q or -d for that.
Default: not set
Specifies the PID file. Without pidfile set, daemonization (-d) is not allowed.
Default: not set
Specifies a list (comma-separated) of addresses where to listen for TCP connections.
You may also use * meaning “listen on all addresses”. When not set,
only Unix socket connections are accepted.
Addresses can be specified numerically (IPv4/IPv6) or by name.
Default: not set
Which port to listen on. Applies to both TCP and Unix sockets.
Default: 6432
Specifies the location for Unix sockets. Applies to both the listening socket and to
server connections. If set to an empty string, Unix sockets are disabled.
A value that starts with @ specifies that a Unix socket in the
abstract namespace should be created (currently supported on Linux and
Windows).
For online reboot (-R) to work, a Unix socket needs to be
configured, and it needs to be in the file-system namespace.
Default: /tmp (empty on Windows)
File system mode for Unix socket. Ignored for sockets in the abstract namespace. Not supported on Windows.
Default: 0777
Group name to use for Unix socket. Ignored for sockets in the abstract namespace. Not supported on Windows.
Default: not set
If set, specifies the Unix user to change to after startup. Works only if PgBouncer is started as root or if it’s already running as the given user. Not supported on Windows.
Default: not set
Specifies when a server connection can be reused by other clients.
Maximum number of client connections allowed.
When this setting is increased, then the file descriptor limits in the
operating system might also have to be increased. Note that the
number of file descriptors potentially used is more than
max_client_conn. If each user connects under its own user name to
the server, the theoretical maximum used is:
max_client_conn + (max pool_size * total databases * total users)
If a database user is specified in the connection string (all users connect under the same user name), the theoretical maximum is:
max_client_conn + (max pool_size * total databases)
The theoretical maximum should never be reached, unless somebody deliberately crafts a special load for it. Still, it means you should set the number of file descriptors to a safely high number.
Search for ulimit in your favorite shell man page.
Note: ulimit does not apply in a Windows environment.
Default: 100
How many server connections to allow per user/database pair. Can be overridden in the per-database configuration.
Default: 20
Add more server connections to pool if below this number. Improves behavior when the normal load suddenly comes back after a period of total inactivity. The value is effectively capped at the pool size.
Only enforced for pools where at least one of the following is true:
[database] section for the pool has a value set for the
user key (aka forced user)Default: 0 (disabled)
How many additional connections to allow to a pool (see reserve_pool_timeout). 0 disables.
Default: 0 (disabled)
If a client has not been serviced in this time, use additional connections from the reserve pool. 0 disables. [seconds]
Default: 5.0
Do not allow more than this many server connections per database (regardless of user). This considers the PgBouncer database that the client has connected to, not the PostgreSQL database of the outgoing connection.
This can also be set per database in the [databases] section.
Note that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.
Default: 0 (unlimited)
Do not allow more than this many server connections per user (regardless of database). This considers the PgBouncer user that is associated with a pool, which is either the user specified for the server connection or in absence of that the user the client has connected as.
This can also be set per user in the [users] section.
Note that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.
Default: 0 (unlimited)
By default, PgBouncer reuses server connections in LIFO (last-in, first-out) manner, so that few connections get the most load. This gives best performance if you have a single server serving a database. But if there is a round-robin system behind a database address (TCP, DNS, or host list), then it is better if PgBouncer also uses connections in that manner, thus achieving uniform load.
Default: 0
By default, PgBouncer tracks client_encoding, datestyle, timezone, standard_conforming_strings
and application_name parameters per client. To allow other parameters to be tracked, they can be
specified here, so that PgBouncer knows that they should be maintained in the client variable cache
and restored in the server whenever the client becomes active.
If you need to specify multiple values, use a comma-separated list (e.g.
default_transaction_read_only, IntervalStyle)
Note: Most parameters cannot be tracked this way. The only parameters that can be tracked are ones that
Postgres reports to the client. Postgres has
an official list of parameters that it reports to the client.
Postgres extensions can change this list though, they can add parameters themselves that they also report,
and they can start reporting already existing parameters that Postgres does not report.
Notably Citus 12.0+ causes Postgres to also report search_path.
The Postgres protocol allows specifying parameters settings, both directly as a
parameter in the startup packet, or inside the options startup
packet. Parameters specified using both of these methods are
supported by track_extra_parameters. However, it’s not possible to include
options itself in track_extra_parameters, only the parameters contained in
options.
Default: IntervalStyle
By default, PgBouncer allows only parameters it can keep track of in startup
packets: client_encoding, datestyle, timezone and standard_conforming_strings.
All others parameters will raise an error. To allow others parameters, they can be
specified here, so that PgBouncer knows that they are handled by the admin and it can ignore them.
If you need to specify multiple values, use a comma-separated list (e.g.
options,extra_float_digits)
The Postgres protocol allows specifying parameters settings, both directly as a
parameter in the startup packet, or inside the options startup
packet. Parameters specified using both of these methods are
supported by ignore_startup_parameters. It’s even possible to include
options itself in track_extra_parameters, which results in any unknown
parameters contained inside options to be ignored.
Default: empty
The peer id used to identify this PgBouncer process in a group of PgBouncer
processes that are peered together. The peer_id value should be unique within
a group of peered PgBouncer processes. When set to 0 pgbouncer peering is
disabled. See the docs for the [peers] section for more information. The
maximum value that can be used for the peer_id is 16383.
Default: 0
Disable the Simple Query protocol (PQexec). Unlike the Extended Query protocol, Simple Query allows multiple queries in one packet, which allows some classes of SQL-injection attacks. Disabling it can improve security. Obviously, this means only clients that exclusively use the Extended Query protocol will stay working.
Default: 0
Add the client host address and port to the application name setting set on connection start.
This helps in identifying the source of bad queries etc. This logic applies
only at the start of a connection. If application_name is later changed with SET,
PgBouncer does not change it again.
Default: 0
Show location of current config file. Changing it will make PgBouncer use another
config file for next RELOAD / SIGHUP.
Default: file from command line
Used on win32 service registration.
Default: pgbouncer
Alias for service_name.
Sets how often the averages shown in various SHOW commands are
updated and how often aggregated statistics are written to the log
(but see log_stats). [seconds]
Default: 60
When this is set to a non-zero value PgBouncer tracks protocol-level named prepared statements related commands sent by the client in transaction and statement pooling mode. PgBouncer makes sure that any statement prepared by a client is available on the backing server connection. Even when the statement was originally prepared on another server connection.
PgBouncer internally examines all the queries that are sent by clients as a prepared
statement, and gives each unique query string an internal name with
the format PGBOUNCER_{unique_id}. If the same query string is prepared
multiple times (possibly by different clients), then these queries share the
same internal name. PgBouncer only prepares the statement on the actual
PostgreSQL server using the internal name (so not the name provided by the
client). PgBouncer keeps track of the name that the client gave to each
prepared statement. It then rewrites each command that uses a prepared
statement to by replacing the client side name with the the internal name (e.g.
replacing my_prepared_statement with PGBOUNCER_123) before forwarding that
command to the server. More importantly, if the prepared statement that the
client wants to execute is not yet prepared on the server (e.g. because a
different server is now assigned to the client than when the client prepared
the statement), then PgBouncer transparently prepares the statement before
executing it.
Note: This tracking and rewriting of prepared statement commands does not work
for SQL-level prepared statement commands, so PREPARE, EXECUTE and
DEALLOCATE are forwarded straight to Postgres. The exception to this rule are
the DEALLOCATE ALL and DISCARD ALL commands, these do work as expected and
will clear the prepared statements that PgBouncer tracked for the client that
sends this command.
The actual value of this setting controls the number of prepared statements kept active in an LRU cache on a single server connection. When the setting is set to 0 prepared statement support for transaction and statement pooling is disabled. To get the best performance you should try to make sure that this setting is larger than the amount of commonly used prepared statements in your application. Keep in mind that the higher this value, the larger the memory footprint of each PgBouncer connection will be on your PostgreSQL server, because it will keep more queries prepared on those connections. It also increases the memory footprint of PgBouncer itself, because it now needs to keep track of query strings.
The impact on PgBouncer memory usage is not that big though:
pkt_buf. This limit is often not reached
though, it only happens when the queries in your prepared statements are
between 2 and 4 times the size of pkt_buf.So if you consider the following as an example scenario:
pkt_buf parameter is set to the default of 4096 (4kB)Then, PgBouncer needs at most the following amount of memory to handle these prepared statements:
200 x 5kB + 1000 x 4 x 4kB = ~17MB of memory.
Tracking prepared statements does not only come with a memory cost, but also
with increased CPU usage, because PgBouncer needs to inspect and rewrite the
queries. Multiple PgBouncer instances can listen on the same port to use more
than one core for processing, see the documentation for the so_reuseport
option for details.
But of course there are also performance benefits to prepared statements. Just
as when connecting to PostgreSQL directly, by preparing a query that is
executed many times, it reduces the total amount of parsing and planning that
needs to be done. The way that PgBouncer tracks prepared statements is
especially beneficial to performance when multiple clients prepare the same
queries. Because client connections automatically reuse a prepared statement on
a server connection, even if it was prepared by another client. As an example, if
you have a pool_size of 20 and you have 100 clients that all prepare the
exact same query, then the query is prepared (and thus parsed) only 20 times on
the PostgreSQL server.
The reuse of prepared statements has one downside. If the return or argument types of a prepared statement changes across executions then PostgreSQL currently throws an error such as:
ERROR: cached plan must not change result type
You can avoid such errors by not having multiple clients that use the exact
same query string in a prepared statement, but expecting different argument or
result types. One of the most common ways of running into this issue is during
a DDL migration where you add a new column or change a column type on an
existing table. In those cases you can run RECONNECT on the PgBouncer admin
console after doing the migration to force a re-prepare of the query and make
the error go away.
Default: 0
PgBouncer handles its own client authentication and has its own database of users. These settings control this.
How to authenticate users.
auth_file may contain both MD5-encrypted and plain-text
passwords. If md5 is configured and a user has a SCRAM secret,
then SCRAM authentication is used automatically instead.auth_file has to contain
SCRAM secrets or plain-text passwords.auth_file.trust method, but the user name given is ignored. Requires that all
databases are configured to log in as a specific user. Additionally, the console
database allows any user to log in as admin.auth_hba_file. This allows different
authentication methods for different access paths, for example: connections
over Unix socket use the peer auth method, connections over TCP
must use TLS.auth_file is ignored. This method is not
compatible with databases using the auth_user option. The service name reported to
PAM is “pgbouncer”. pam is not supported in the HBA configuration file.HBA configuration file to use when auth_type is hba. See
section HBA file format below about details.
Default: not set
Identity map file to use when auth_type is hba and a user map will be defined. See
section Ident map file format below about details.
Default: not set
The name of the file to load user names and passwords from. See section Authentication file format below about details.
Most authentication types (see above) require that either auth_file
or auth_user be set; otherwise there would be no users defined.
Default: not set
If auth_user is set, then any user not specified in auth_file will be
queried through the auth_query query from pg_shadow in the database,
using auth_user. The password of auth_user will be taken from auth_file.
(If the auth_user does not require a password then it does not need
to be defined in auth_file.)
Direct access to pg_shadow requires admin rights. It’s preferable to use a non-superuser that calls a SECURITY DEFINER function instead.
Default: not set
Query to load user’s password from database.
Direct access to pg_shadow requires admin rights. It’s preferable to use a non-superuser that calls a SECURITY DEFINER function instead.
Note that the query is run inside the target database. So if a function is used, it needs to be installed into each database.
Default: SELECT usename, passwd FROM pg_shadow WHERE usename=$1
Database name in the [database] section to be used for authentication purposes. This
option can be either global or overridden in the connection string if this parameter is
specified.
Toggles syslog on/off. On Windows, the event log is used instead.
Default: 0
Under what name to send logs to syslog.
Default: pgbouncer (program name)
Under what facility to send logs to syslog.
Possibilities: auth, authpriv, daemon, user, local0-7.
Default: daemon
Log successful logins.
Default: 1
Log disconnections with reasons.
Default: 1
Log error messages the pooler sends to clients.
Default: 1
Write aggregated statistics into the log, every stats_period. This
can be disabled if external monitoring tools are used to grab the same
data from SHOW commands.
Default: 1
Increase verbosity. Mirrors the “-v” switch on the command line.
For example, using “-v -v” on the command line is the same as verbose=2.
Default: 0
Comma-separated list of database users that are allowed to connect and
run all commands on the console. Ignored when auth_type is any,
in which case any user name is allowed in as admin.
Default: empty
Comma-separated list of database users that are allowed to connect and
run read-only queries on the console. That means all SHOW commands except
SHOW FDS.
Default: empty
Query sent to server on connection release, before making it
available to other clients. At that moment no transaction is in
progress, so the value should not include ABORT or ROLLBACK.
The query is supposed to clean any changes made to the database session
so that the next client gets the connection in a well-defined state. The default is
DISCARD ALL, which cleans everything, but that leaves the next client
no pre-cached state. It can be made lighter, e.g. DEALLOCATE ALL
to just drop prepared statements, if the application does not break when
some state is kept around.
When transaction pooling is used, the server_reset_query is not used,
because in that mode, clients must not use any session-based features, since each transaction
ends up in a different connection and thus gets a different session state.
Default: DISCARD ALL
Whether server_reset_query should be run in all pooling modes. When this
setting is off (default), the server_reset_query will be run only in pools
that are in sessions-pooling mode. Connections in transaction-pooling mode
should not have any need for a reset query.
This setting is for working around broken setups that run applications that use session features over a transaction-pooled PgBouncer. It changes non-deterministic breakage to deterministic breakage: Clients always lose their state after each transaction.
Default: 0
How long to keep released connections available for immediate re-use, without running
server_check_query on it. If 0 then the check is always run.
Default: 30.0
Simple do-nothing query to check if the server connection is alive.
If an empty string, then sanity checking is disabled.
Default: select 1
Disconnect a server in session pooling mode immediately or after the
end of the current transaction if it is in “close_needed” mode (set by
RECONNECT, RELOAD that changes connection settings, or DNS
change), rather than waiting for the session end. In statement or
transaction pooling mode, this has no effect since that is the default
behavior there.
If because of this setting a server connection is closed before the end of the client session, the client connection is also closed. This ensures that the client notices that the session has been interrupted.
This setting makes connection configuration changes take effect sooner if session pooling and long-running sessions are used. The downside is that client sessions are liable to be interrupted by a configuration change, so client applications will need logic to reconnect and reestablish session state. But note that no transactions will be lost, because running transactions are not interrupted, only idle sessions.
Default: 0
The pooler will close an unused (not currently linked to any client connection) server connection that has been connected longer than this. Setting it to 0 means the connection is to be used only once, then closed. [seconds]
This can also be set per database in the [databases] section.
Default: 3600.0
If a server connection has been idle more than this many seconds it will be closed. If 0 then this timeout is disabled. [seconds]
Default: 600.0
If connection and login don’t finish in this amount of time, the connection will be closed. [seconds]
Default: 15.0
If login to the server failed, because of failure to connect or from authentication, the pooler waits this much before retrying to connect. During the waiting interval, new clients trying to connect to the failing server will get an error immediately without another connection attempt. [seconds]
The purpose of this behavior is that clients don’t unnecessarily queue
up waiting for a server connection to become available if the server
is not working. However, it also means that if a server is
momentarily failing, for example during a restart or if the
configuration was erroneous, then it will take at least this long
until the pooler will consider connecting to it again. Planned events
such as restarts should normally be managed using the PAUSE command
to avoid this.
Default: 15.0
If a client connects but does not manage to log in in this amount of time, it
will be disconnected. Mainly needed to avoid dead connections stalling
SUSPEND and thus online restart. [seconds]
Default: 60.0
If the automatically created (via “*”) database pools have been unused this many seconds, they are freed. The negative aspect of that is that their statistics are also forgotten. [seconds]
Default: 3600.0
How long DNS lookups can be cached. The actual DNS TTL is ignored. [seconds]
Default: 15.0
How long DNS errors and NXDOMAIN DNS lookups can be cached. [seconds]
Default: 15.0
Period to check if a zone serial has changed.
PgBouncer can collect DNS zones from host names (everything after first dot) and then periodically check if the zone serial changes. If it notices changes, all host names under that zone are looked up again. If any host IP changes, its connections are invalidated.
Works only with c-ares backend (configure option --with-cares).
Default: 0.0 (disabled)
The location of a custom resolv.conf file. This is to allow
specifying custom DNS servers and perhaps other name resolution
options, independent of the global operating system configuration.
Requires evdns (>= 2.0.3) or c-ares (>= 1.15.0) backend.
The parsing of the file is done by the DNS backend library, not PgBouncer, so see the library’s documentation for details on allowed syntax and directives.
Default: empty (use operating system defaults)
TLS mode to use for connections from clients. TLS connections
are disabled by default. When enabled, client_tls_key_file
and client_tls_cert_file must be also configured to set up
the key and certificate PgBouncer uses to accept client connections.
The most common certificate file format usable by PgBouncer is pem.
allow.verify-ca.Private key for PgBouncer to accept client connections.
Default: not set
Certificate for private key. Clients can validate it.
Default: not set
Root certificate file to validate client certificates.
Default: not set
Which TLS protocol versions are allowed. Allowed values: tlsv1.0, tlsv1.1, tlsv1.2, tlsv1.3.
Shortcuts: all (tlsv1.0,tlsv1.1,tlsv1.2,tlsv1.3), secure (tlsv1.2,tlsv1.3), legacy (all).
Default: secure
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts:
default/secure/fast/normal (these all use system wide OpenSSL defaults)all (enables all ciphers, not recommended)Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections.
Default: default
Elliptic Curve name to use for ECDH key exchanges.
Allowed values: none (DH is disabled), auto (256-bit ECDH), curve name
Default: auto
DHE key exchange type.
Allowed values: none (DH is disabled), auto (2048-bit DH), legacy (1024-bit DH)
Default: auto
TLS mode to use for connections to PostgreSQL servers. The default mode is
prefer.
server_tls_ca_file. Server host name is not checked
against certificate.server_tls_ca_file. Server host name must match
certificate information.Root certificate file to validate PostgreSQL server certificates.
Default: not set
Private key for PgBouncer to authenticate against PostgreSQL server.
Default: not set
Certificate for private key. PostgreSQL server can validate it.
Default: not set
Which TLS protocol versions are allowed. Allowed values: tlsv1.0, tlsv1.1, tlsv1.2, tlsv1.3.
Shortcuts: all (tlsv1.0,tlsv1.1,tlsv1.2,tlsv1.3), secure (tlsv1.2,tlsv1.3), legacy (all).
Default: secure
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts:
default/secure/fast/normal (these all use system wide OpenSSL defaults)all (enables all ciphers, not recommended)Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections.
Default: default
Setting the following timeouts can cause unexpected errors.
Queries running longer than that are canceled. This should be used only with
a slightly smaller server-side statement_timeout, to apply only for network
problems. [seconds]
Default: 0.0 (disabled)
Maximum time queries are allowed to spend waiting for execution. If the query is not assigned to a server during that time, the client is disconnected. 0 disables. If this is disabled, clients will be queued indefinitely. [seconds]
This setting is used to prevent unresponsive servers from grabbing up connections. It also helps when the server is down or rejects connections for any reason.
Default: 120.0
Maximum time cancellation requests are allowed to spend waiting for execution. If the cancel request is not assigned to a server during that time, the client is disconnected. 0 disables. If this is disabled, cancel requests will be queued indefinitely. [seconds]
This setting is used to prevent a client locking up when a cancel cannot be forwarded due to the server being down.
Default: 10.0
Client connections idling longer than this many seconds are closed. This should be larger than the client-side connection lifetime settings, and only used for network problems. [seconds]
Default: 0.0 (disabled)
If a client has been in “idle in transaction” state longer, it will be disconnected. [seconds]
Default: 0.0 (disabled)
How long to wait for buffer flush during SUSPEND or reboot (-R).
A connection is dropped if the flush does not succeed. [seconds]
Default: 10
Internal buffer size for packets. Affects size of TCP packets sent and general memory usage. Actual libpq packets can be larger than this, so no need to set it large.
Default: 4096
Maximum size for PostgreSQL packets that PgBouncer allows through. One packet is either one query or one result set row. The full result set can be larger.
Default: 2147483647
Backlog argument for listen(2). Determines how many new unanswered connection attempts are kept in the queue. When the queue is full, further new connections are dropped.
Default: 128
How many times to process data on one connection, before proceeding.
Without this limit, one connection with a big result set can stall
PgBouncer for a long time. One loop processes one pkt_buf amount of data.
0 means no limit.
Default: 5
Specifies whether to set the socket option SO_REUSEPORT on TCP
listening sockets. On some operating systems, this allows running
multiple PgBouncer instances on the same host listening on the same
port and having the kernel distribute the connections automatically.
This option is a way to get PgBouncer to use more CPU cores.
(PgBouncer is single-threaded and uses one CPU core per instance.)
The behavior in detail depends on the operating system kernel. As of
this writing, this setting has the desired effect on (sufficiently
recent versions of) Linux, DragonFlyBSD, and FreeBSD. (On FreeBSD, it
applies the socket option SO_REUSEPORT_LB instead.) Some other
operating systems support the socket option but it won’t have the
desired effect: It will allow multiple processes to bind to the same
port but only one of them will get the connections. See your
operating system’s setsockopt() documentation for details.
On systems that don’t support the socket option at all, turning this setting on will result in an error.
Each PgBouncer instance on the same host needs different settings for
at least unix_socket_dir and pidfile, as well as logfile if that
is used. Also note that if you make use of this option, you can no
longer connect to a specific PgBouncer instance via TCP/IP, which
might have implications for monitoring and metrics collection.
To make sure query cancellations keep working, you should set up PgBouncer
peering between the different PgBouncer processes. For details look at docs
for the peer_id configuration option and the peers configuration section.
There’s also an example that uses peering and so_reuseport in the example
section of these docs.
Default: 0
Sets the TCP_DEFER_ACCEPT socket option; see man 7 tcp for
details. (This is a Boolean option: 1 means enabled. The actual
value set if enabled is currently hardcoded to 45 seconds.)
This is currently only supported on Linux.
Default: 1 on Linux, otherwise 0
Default: not set
Turns on basic keepalive with OS defaults.
On Linux, the system defaults are tcp_keepidle=7200, tcp_keepintvl=75, tcp_keepcnt=9. They are probably similar on other operating systems.
Default: 1
Default: not set
Default: not set
Default: not set
Sets the TCP_USER_TIMEOUT socket option. This specifies the maximum
amount of time in milliseconds that transmitted data may remain
unacknowledged before the TCP connection is forcibly closed. If set
to 0, then operating system’s default is used.
This is currently only supported on Linux.
Default: 0
The section [databases] defines the names of the databases that
clients of PgBouncer can connect to and specifies where those
connections will be routed. The section contains key=value lines like
dbname = connection string
where the key will be taken as a database name and the value as a connection string, consisting of key=value pairs of connection parameters, described below (similar to libpq, but the actual libpq is not used and the set of available features is different). Example:
foodb = host=host1.example.com port=5432
bardb = host=localhost dbname=bazdb
The database name can contain characters _0-9A-Za-z without quoting.
Names that contain other characters need to be quoted with standard SQL
identifier quoting: double quotes, with “” for a single instance of a double quote.
The database name “pgbouncer” is reserved for the admin console and cannot be used as a key here.
“*” acts as a fallback database: If the exact name does not exist, its value is taken as connection string for the requested database. For example, if there is an entry (and no other overriding entries)
* = host=foo
then a connection to PgBouncer specifying a database “bar” will effectively behave as if an entry
bar = host=foo dbname=bar
exists (taking advantage of the default for dbname being the
client-side database name; see below).
Such automatically created database entries are cleaned up
if they stay idle longer than the time specified by the autodb_idle_timeout
parameter.
Destination database name.
Default: same as client-side database name
Host name or IP address to connect to. Host names are resolved
at connection time, the result is cached per dns_max_ttl parameter.
When a host name’s resolution changes, existing server connections are
automatically closed when they are released (according to the pooling
mode), and new server connections immediately use the new resolution.
If DNS returns several results, they are used in a round-robin
manner.
If the value begins with /, then a Unix socket in the file-system
namespace is used. If the value begins with @, then a Unix socket
in the abstract namespace is used.
A comma-separated list of host names or addresses can be specified.
In that case, connections are made in a round-robin manner. (If a
host list contains host names that in turn resolve via DNS to multiple
addresses, the round-robin systems operate independently. This is an
implementation dependency that is subject to change.) Note that in a
list, all hosts must be available at all times: There are no
mechanisms to skip unreachable hosts or to select only available hosts
from a list or similar. (This is different from what a host list in
libpq means.) Also note that this only affects how the destinations
of new connections are chosen. See also the setting
server_round_robin for how clients are assigned to already
established server connections.
Examples:
host=localhost
host=127.0.0.1
host=2001:0db8:85a3:0000:0000:8a2e:0370:7334
host=/var/run/postgresql
host=192.168.0.1,192.168.0.2,192.168.0.3
Default: not set, meaning to use a Unix socket
Default: 5432
If user= is set, all connections to the destination database will be
done with the specified user, meaning that there will be only one pool
for this database.
Otherwise, PgBouncer logs into the destination database with the client user name, meaning that there will be one pool per user.
If no password is specified here, the password from the auth_file will
be used for the user specified above. Dynamic forms of password discovery
such as auth_query are not currently supported.
Override of the global auth_user setting, if specified.
Override of the global auth_query setting, if specified. The entire SQL statement needs to be enclosed in single quotes.
Override of the global auth_dbname setting, if specified.
Set the maximum size of pools for this database. If not set,
the default_pool_size is used.
Set the minimum pool size for this database. If not set, the global min_pool_size is
used.
Only enforced if at least one of the following is true:
[database] section has a value set for the user key
(aka forced user)Set additional connections for this database. If not set, reserve_pool_size is
used.
Query to be executed after a connection is established, but before allowing the connection to be used by any clients. If the query raises errors, they are logged but ignored otherwise.
Set the pool mode specific to this database. If not set,
the default pool_mode is used.
Configure a database-wide maximum (i.e. all pools within the database will not have more than this many server connections).
Configure the server_lifetime per database. If not set the database will fall back
to the instance wide configured value for server_lifetime
Ask specific client_encoding from server.
Ask specific datestyle from server.
Ask specific timezone from server.
This section contains key=value lines like
user1 = settings
where the key will be taken as a user name and the value as a list of key=value pairs of configuration settings specific for this user. Example:
user1 = pool_mode=session
Only a few settings are available here.
Note that when auth_file is configured, if a user is defined in this section
but not listed in auth_file, pgBouncer will attempt to use auth_query to
find a password for that user if auth_user is set. If auth_user is not set,
pgBouncer will pretend the user exists and fail to return “no such user”
messages to the client, but neither will it accept any provided password.
Set the maximum size of pools for all connections from this user. If not set,
the database or default_pool_size is used.
Set the pool mode to be used for all connections from this user. If not set, the
database or default pool_mode is used.
Configure a maximum for the user (i.e. all pools with the user will not have more than this many server connections).
The section [peers] defines the peers that PgBouncer can forward cancellation
requests to and where those cancellation requests will be routed.
PgBouncer processes can be peered together in a group by defining a peer_id
value and a [peers] section in the configs of all the PgBouncer processes.
These PgBouncer processes can then forward cancellations requests to the process
that it originated from. This is needed to make cancellations work when
multiple PgBouncer processes (possibly on different servers) are behind the same
TCP load balancer. Cancellation requests are sent over different TCP
connections than the query they are cancelling, so a TCP load balancer might
send the cancellation request connection to a different process than the one
that it was meant for. By peering them these cancellation requests eventually
end up at the right process. A more in-depth explanation is provided in this
recording of a conference talk.
The section contains key=value lines like
peer_id = connection string
Where the key will be taken as a peer_id and the value as a connection string,
consisting of key=value pairs of connection parameters, described below (similar
to libpq, but the actual libpq is not used and the set of available features is
different). Example:
1 = host=host1.example.com
2 = host=/tmp/pgbouncer-2 port=5555
Note 1: For peering to work, the peer_id of each PgBouncer process in the group
must be unique within the peered group. And the [peers] section should
contain entries for each of those peer ids. An example can be found in the
examples section of these docs. It is allowed, but not necessary, for the
[peers] section to contain the peer_id of the PgBouncer that the config is
for. Such an entry will be ignored, but it is allowed to config management easy.
Because it allows using the exact same [peers] section for multiple
configs.
Note 2: Cross-version peering is supported as long as all peers are on the same side of the v1.21.0 version boundary. In v1.21.0 some breaking changes were made in how we encode the cancellation tokens that made them incompatible with the ones created by earlier versions.
Host name or IP address to connect to. Host names are resolved at connection
time, the result is cached per dns_max_ttl parameter. If DNS returns several
results, they are used in a round-robin manner. But in general it’s not
recommended to use a hostname that resolves to multiple IPs, because then the
cancel request might still be forwarded to the wrong node and it would need to
be forwarded again (which is only allowed up to three times).
If the value begins with /, then a Unix socket in the file-system namespace is
used. If the value begins with @, then a Unix socket in the abstract
namespace is used.
Examples:
host=localhost
host=127.0.0.1
host=2001:0db8:85a3:0000:0000:8a2e:0370:7334
host=/var/run/pgbouncer-1
Default: 6432
Set the maximum number of cancel requests that can be in flight to the peer at
the same time. It’s quite normal for cancel requests to arrive in bursts, e.g.
when the backing Postgres server slow or down. So it’s important for
pool_size to not be so low that it cannot handle these bursts.
If not set, the default_pool_size is used.
The PgBouncer configuration file can contain include directives, which specify another configuration file to read and process. This allows splitting the configuration file into physically separate parts. The include directives look like this:
%include filename
If the file name is not an absolute path, it is taken as relative to the current working directory.
This section describes the format of the file specified by the
auth_file setting. It is a text file in the following format:
"username1" "password" ...
"username2" "md5abcdef012342345" ...
"username2" "SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>"
There should be at least 2 fields, surrounded by double quotes. The first field is the user name and the second is either a plain-text, a MD5-hashed password, or a SCRAM secret. PgBouncer ignores the rest of the line. Double quotes in a field value can be escaped by writing two double quotes.
PostgreSQL MD5-hashed password format:
"md5" + md5(password + username)
So user admin with password 1234 will have MD5-hashed password
md545f2603610af569b6155c45067268c6b.
PostgreSQL SCRAM secret format:
SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>
See the PostgreSQL documentation and RFC 5803 for details on this.
The passwords or secrets stored in the authentication file serve two purposes. First, they are used to verify the passwords of incoming client connections, if a password-based authentication method is configured. Second, they are used as the passwords for outgoing connections to the backend server, if the backend server requires password-based authentication (unless the password is specified directly in the database’s connection string).
If the password is stored in plain text, it can be used for any password-based authentication used in the backend server; plain text, MD5 or SCRAM (see https://www.postgresql.org/docs/current/auth-password.html for details).
MD5-hashed passwords can be used if backend server uses MD5 authentication (or specific users have MD5-hashed passwords).
SCRAM secrets can only be used for logging into a server if the client authentication also uses SCRAM, the PgBouncer database definition does not specify a user name, and the SCRAM secrets are identical in PgBouncer and the PostgreSQL server (same salt and iterations, not merely the same password). This is due to an inherent security property of SCRAM: The stored SCRAM secret cannot by itself be used for deriving login credentials.
The authentication file can be written by hand, but it’s also useful
to generate it from some other list of users and passwords. See
./etc/mkauth.py for a sample script to generate the authentication
file from the pg_shadow system table. Alternatively, use
auth_query instead of auth_file to avoid having to maintain a
separate authentication file.
If the backend server is configured to use SCRAM password authentication PgBouncer cannot successfully authenticate if it does not know either a) user password in plain text or b) corresponding SCRAM secret.
Some cloud providers (i.e. AWS RDS) prohibit access to PostgreSQL sensitive system tables
for fetching passwords. Even for the most privileged user (i.e. member of rds_superuser) the
select * from pg_authid; returns the ERROR: permission denied for table pg_authid.
That is a known behaviour
(blog).
Therefore, fetching an existing SCRAM secret once it has been stored in a managed server is impossible which makes it hard to configure PgBouncer to use the same SCRAM secret. Nevertheless, SCRAM secret can still be configured and used on both sides using the following trick:
Generate SCRAM secret for arbitrary password with a tool that is capable of printing out the secret.
For example psql --echo-hidden and the command \password prints out the SCRAM secret
to the console before sending it over to the server.
$ psql --echo-hidden <connection_string>
postgres=# \password <role_name>
Enter new password for user "<role_name>":
Enter it again:
********* QUERY **********
ALTER USER <role_name> PASSWORD 'SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>'
**************************
Note down the SCRAM secret from the QUERY and set it in PgBouncer’s userlist.txt.
If you used a tool other than psql --echo-hidden then you need to set the SCRAM secret also in the server
(you can use alter role <role_name> password '<scram_secret>' for that).
The location of the HBA file is specified by the setting
auth_hba_file. It is only used if auth_type is set to hba.
The file follows the format of the PostgreSQL pg_hba.conf file
(see https://www.postgresql.org/docs/current/auth-pg-hba-conf.html).
local, host, hostssl, hostnossl.all, replication, sameuser, @file, multiple names. Not supported: samerole, samegroup.all, @file, multiple names. Not supported: +groupname.all, IPv4, IPv6. Not supported: samehost, samenet, DNS names, domain prefixes.auth_type
are supported, plus peer and reject, but except any and pam, which only work globally.map=) parameter is supported when auth_type is cert or peer.The location of the ident map file is specified by the setting
auth_ident_file. It is only loaded if auth_type is set to hba.
The file format is a simplified variation of the PostgreSQL ident map file (see https://www.postgresql.org/docs/current/auth-username-maps.html).
map-name system-username database-username.all or a single postgres user name. Not supported: +groupname, regular expressions.Small example configuration:
[databases]
template1 = host=localhost dbname=template1 auth_user=someuser
[pgbouncer]
pool_mode = session
listen_port = 6432
listen_addr = localhost
auth_type = md5
auth_file = users.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
admin_users = someuser
stats_users = stat_collector
Database examples:
[databases]
; foodb over Unix socket
foodb =
; redirect bardb to bazdb on localhost
bardb = host=localhost dbname=bazdb
; access to destination database will go with single user
forcedb = host=localhost port=300 user=baz password=foo client_encoding=UNICODE datestyle=ISO
Example of a secure function for auth_query:
CREATE OR REPLACE FUNCTION pgbouncer.user_lookup(in i_username text, out uname text, out phash text)
RETURNS record AS $$
BEGIN
SELECT usename, passwd FROM pg_catalog.pg_shadow
WHERE usename = i_username INTO uname, phash;
RETURN;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;
REVOKE ALL ON FUNCTION pgbouncer.user_lookup(text) FROM public, pgbouncer;
GRANT EXECUTE ON FUNCTION pgbouncer.user_lookup(text) TO pgbouncer;
Example configs for 2 peered PgBouncer processes to create a multi-core
PgBouncer setup using so_reuseport. The config for the first process:
[databases]
postgres = host=localhost dbname=postgres
[peers]
1 = host=/tmp/pgbouncer1
2 = host=/tmp/pgbouncer2
[pgbouncer]
listen_addr=127.0.0.1
auth_file=auth_file.conf
so_reuseport=1
unix_socket_dir=/tmp/pgbouncer1
peer_id=1
The config for the second process:
[databases]
postgres = host=localhost dbname=postgres
[peers]
1 = host=/tmp/pgbouncer1
2 = host=/tmp/pgbouncer2
[pgbouncer]
listen_addr=127.0.0.1
auth_file=auth_file.conf
so_reuseport=1
; only unix_socket_dir and peer_id are different
unix_socket_dir=/tmp/pgbouncer2
peer_id=2
pgbouncer(1) - man page for general usage, console commands