PgBouncer
pgbouncer.ini
Description
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.
Generic settings
logfile
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
pidfile
Specifies the PID file. Without pidfile set, daemonization (-d) is not allowed.
Default: not set
listen_addr
Specifies a list 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
unix_socket_dir
Specifies location for Unix sockets. Applies to both listening socket and server connections. If set to an empty string, Unix sockets are disabled. Required for online reboot (-R) to work.
Default: /tmp (empty on Windows)
user
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 given user. Not supported on Windows.
Default: not set
auth_file
The name of the file to load user names and passwords from. See section Authentication file format below about details.
Default: not set
auth_type
How to authenticate users.
- pam
-
PAM is used to authenticate users,
auth_fileis ignored. This method is not compatible with databases using theauth_useroption. The service name reported to PAM is “pgbouncer”.pamis not supported in the HBA configuration file. - hba
-
The actual authentication type is loaded from
auth_hba_file. This allows different authentication methods for different access paths, for example: connections over Unix socket use thepeerauth method, connections over TCP must use TLS. - cert
-
Client must connect over TLS connection with a valid client certificate. The user name is then taken from the CommonName field from the certificate.
- md5
-
Use MD5-based password check. This is the default authentication method.
auth_filemay contain both MD5-encrypted and plain-text passwords. Ifmd5is configured and a user has a SCRAM secret, then SCRAM authentication is used automatically instead. - scram-sha-256
-
Use password check with SCRAM-SHA-256.
auth_filehas to contain SCRAM secrets or plain-text passwords. - plain
-
The clear-text password is sent over the wire. Deprecated.
- trust
-
No authentication is done. The user name must still exist in
auth_file. - any
-
Like the
trustmethod, 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_query
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
auth_user
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
pool_mode
Specifies when a server connection can be reused by other clients.
- session
-
Server is released back to pool after client disconnects. Default.
- transaction
-
Server is released back to pool after transaction finishes.
- statement
-
Server is released back to pool after query finishes. Transactions spanning multiple statements are disallowed in this mode.
max_client_conn
Maximum number of client connections allowed. When increased then the file descriptor limits should also be increased. Note that the actual number of file descriptors used is more than max_client_conn. The theoretical maximum used is:
max_client_conn + (max pool_size * total databases * total users)
if each user connects under its own user name to the server. 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 be never 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
default_pool_size
How many server connections to allow per user/database pair. Can be overridden in the per-database configuration.
Default: 20
min_pool_size
Add more server connections to pool if below this number. Improves behavior when usual load comes suddenly back after period of total inactivity. The value is effectively capped at the pool size.
Default: 0 (disabled)
reserve_pool_size
How many additional connections to allow to a pool (see reserve_pool_timeout). 0 disables.
Default: 0 (disabled)
reserve_pool_timeout
If a client has not been serviced in this many seconds, use additional connections from the reserve pool. 0 disables.
Default: 5.0
max_db_connections
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)
max_user_connections
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)
server_round_robin
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 TCP round-robin behind a database IP address, then it is better if PgBouncer also uses connections in that manner, thus achieving uniform load.
Default: 0
ignore_startup_parameters
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.
Default: empty
disable_pqexec
Disable Simple Query protocol (PQexec). Unlike 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
application_name_add_host
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 on start of connection. If application_name is later changed with SET, PgBouncer does not change it again.
Default: 0
Log settings
syslog_facility
Under what facility to send logs to syslog. Possibilities: auth, authpriv, daemon, user, local0-7.
Default: daemon
Console access control
Connection sanity checks, timeouts
server_reset_query
Query sent to server on connection release, before making it available to other clients. At that moment no transaction is in progress so it 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, as clients must not use any session-based features as each transaction ends up in a different connection and thus gets a different session state.
Default: DISCARD ALL
server_reset_query_always
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
server_check_delay
How long to keep released connections available for immediate re-use, without running sanity-check queries on it. If 0 then the query is ran always.
Default: 30.0
server_check_query
Simple do-nothing query to check if the server connection is alive.
If an empty string, then sanity checking is disabled.
Default: SELECT 1;
server_fast_close
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
server_lifetime
The pooler will close an unused 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]
Default: 3600.0
server_idle_timeout
If a server connection has been idle more than this many seconds it will be dropped. If 0 then timeout is disabled. [seconds]
Default: 600.0
server_connect_timeout
If connection and login won’t finish in this amount of time, the connection will be closed. [seconds]
Default: 15.0
server_login_retry
If login failed, because of failure from connect() or authentication that pooler waits this much before retrying to connect. [seconds]
Default: 15.0
client_login_timeout
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
autodb_idle_timeout
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
dns_max_ttl
How long the DNS lookups can be cached. If a DNS lookup returns several answers, PgBouncer will robin-between them in the meantime. The actual DNS TTL is ignored. [seconds]
Default: 15.0
dns_zone_check_period
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 UDNS and c-ares backends (--with-udns or --with-cares to configure).
Default: 0.0 (disabled)
resolv_conf
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 settings
client_tls_sslmode
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.
- disable
-
Plain TCP. If client requests TLS, it’s ignored. Default.
- allow
-
If client requests TLS, it is used. If not, plain TCP is used. If the client presents a client certificate, it is not validated.
- prefer
-
Same as
allow. - require
-
Client must use TLS. If not, the client connection is rejected. If the client presents a client certificate, it is not validated.
- verify-ca
-
Client must use TLS with valid client certificate.
- verify-full
-
Same as
verify-ca.
client_tls_protocols
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
client_tls_ciphers
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts: default/secure, compat/legacy, insecure/all, normal, fast.
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: fast
client_tls_ecdhcurve
Elliptic Curve name to use for ECDH key exchanges.
Allowed values: none (DH is disabled), auto (256-bit ECDH), curve name.
Default: auto
client_tls_dheparams
DHE key exchange type.
Allowed values: none (DH is disabled), auto (2048-bit DH), legacy (1024-bit DH).
Default: auto
server_tls_sslmode
TLS mode to use for connections to PostgreSQL servers. TLS connections are disabled by default.
- disable
-
Plain TCP. TCP is not even requested from the server. Default.
- allow
-
FIXME: if server rejects plain, try TLS?
- prefer
-
TLS connection is always requested first from PostgreSQL, when refused connection will be established over plain TCP. Server certificate is not validated.
- require
-
Connection must go over TLS. If server rejects it, plain TCP is not attempted. Server certificate is not validated.
- verify-ca
-
Connection must go over TLS and server certificate must be valid according to
server_tls_ca_file. Server host name is not checked against certificate. - verify-full
-
Connection must go over TLS and server certificate must be valid according to
server_tls_ca_file. Server host name must match certificate information.
server_tls_ca_file
Root certificate file to validate PostgreSQL server certificates.
Default: not set
server_tls_key_file
Private key for PgBouncer to authenticate against PostgreSQL server.
Default: not set
server_tls_cert_file
Certificate for private key. PostgreSQL server can validate it.
Default: not set
server_tls_protocols
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
server_tls_ciphers
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts: default/secure, compat/legacy, insecure/all, normal, fast.
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: fast
Dangerous timeouts
Setting the following timeouts can cause unexpected errors.
query_timeout
Queries running longer than that are canceled. This should be used only with slightly smaller server-side statement_timeout, to apply only for network problems. [seconds]
Default: 0.0 (disabled)
query_wait_timeout
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. This is used to prevent unresponsive servers from grabbing up connections. [seconds]
It also helps when the server is down or database rejects connections for any reason. If this is disabled, clients will be queued indefinitely.
Default: 120
client_idle_timeout
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)
Low-level network settings
pkt_buf
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
max_packet_size
Maximum size for PostgreSQL packets that PgBouncer allows through. One packet is either one query or one result set row. Full result set can be larger.
Default: 2147483647
listen_backlog
Backlog argument for listen(2). Determines how many new unanswered connection attempts are kept in queue. When the queue is full, further new connections are dropped.
Default: 128
sbuf_loopcnt
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
so_reuseport
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.
Default: 0
tcp_defer_accept
For details on this and other TCP options, please see man 7 tcp.
Default: 45 on Linux, otherwise 0
tcp_keepalive
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
tcp_user_timeout
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
Section [databases]
This contains key=value pairs where the key will be taken as a database name and the value as a libpq connection string style list of key=value pairs. Not all features known from libpq can be used (service=, .pgpass), since the actual libpq is not used.
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.
“*” acts as a fallback database: if the exact name does not exist, its value is taken as connection string for requested database. Such automatically created database entries are cleaned up if they stay idle longer than the time specified by the autodb_idle_timeout parameter.
host
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 round-robin manner.
Default: not set, meaning to use a Unix socket
user
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.
password
The length for password is limited to 160 characters maximum.
If no password is specified here, the password from the auth_file or auth_query will be used.
pool_size
Set the maximum size of pools for this database. If not set, the default_pool_size is used.
connect_query
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.
Section [users]
This contains key=value pairs where the key will be taken as a user name and the value as a libpq connection string style list of key=value pairs of configuration settings specific for this user. Only a few settings are available here.
Include directive
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 absolute path it is taken as relative to current working directory.
Authentication file format
PgBouncer needs its own user database. The users are loaded from 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). The latter works if the password is stored in plain text or MD5-hashed. 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.
HBA file format
It follows the format of the PostgreSQL pg_hba.conf file (see https://www.postgresql.org/docs/current/auth-pg-hba-conf.html).
-
Supported record types:
local,host,hostssl,hostnossl. -
Database field: Supports
all,sameuser,@file, multiple names. Not supported:replication,samerole,samegroup. -
User name field: Supports
all,@file, multiple names. Not supported:+groupname. -
Address field: Supports IPv4, IPv6. Not supported: DNS names, domain prefixes.
-
Auth-method field: Only methods supported by PgBouncer’s
auth_typeare supported, exceptanyandpam, which only work globally. User name map (map=) parameter is not supported.
Example
Minimal config:
[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 defaults:
[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;