Upstream#
Provides context for describing groups of servers that can be used in the proxy_pass directive. Describes a group of servers. Servers can listen on different ports. In addition, servers listening on TCP and UNIX domain sockets can be mixed. Example: By default, connections are distributed between the servers using a weighted round-robin balancing method. In the above example, each 7 connections will be distributed as follows: 5 connections go to backend1.example.com:1935 and one connection to each of the second and third servers. If an error occurs during communication with a server, the connection will be passed to the next server, and so on until all of the functioning servers will be tried. If communication with all servers fails, the connection will be closed. Defines the address and other parameters of a server. The address can be specified as a domain name or IP address with an obligatory port, or as a UNIX domain socket path specified after the The following parameters can be defined: Sets the weight of the server; by default, 1. Limits the maximum number of simultaneous active connections to the proxied server. Default value is Here, an unsuccessful attempt is an error or timeout while establishing a
connection with the server. Note If a If an upstream contains only one server
after all its The default number of attempts. Disables the accounting of attempts. By default, this is set to 10 seconds. Note If a If an upstream contains only one server
after all its Marks the server as a backup server. It will be passed requests when the primary servers are unavailable. Marks the server as permanently unavailable. Marks the server as draining; this means
it receives only requests from the sessions
that were bound earlier with sticky.
Otherwise it behaves similarly to Caution The The Added in version 1.3.0. Enables monitoring changes to the list of IP addresses that
corresponds to a domain name, updating it without a configuration reload.
The group must reside in a
shared memory zone;
also, a resolver must be defined. Enables resolving DNS SRV records and sets the service name.
For this parameter to work, the resolve parameter must also be specified,
without specifying the server port in the hostname. If there are no dots in the service name,
the name is formed according to the RFC standard:
the service name is prefixed with Angie resolves the SRV records
by combining the normalized service name and the hostname
and obtaining the list of servers for the combination via DNS,
along with their priorities and weights. Top-priority SRV records
(ones that share the minimum priority value)
resolve into primary servers,
and other records become backup servers.
If Weight is similar to the This example will look up the Added in version 1.2.0: Angie Added in version 1.1.0-P1: Angie PRO Sets the server ID in the group. If the parameter is not specified,
the ID is set as a hexadecimal MD5 hash
of the IP address and port or UNIX domain socket path. Added in version 1.4.0. Sets the time for a server to recover its weight
when returning to service
with round-robin or least_conn
load balancing methods. If the parameter is set
and a server is again considered healthy
after a failure according to max_fails and upstream_probe (PRO),
the server gradually recovers its designated weight
over the specified time period. If the parameter is not set,
in a similar situation
the server immediately starts working with its designated weight. Note If only one Added in version 1.4.0: PRO Specifies the file where the upstream server list is persistently stored.
When installing from
our packages,
a dedicated directory
The server list format here is similar to Caution To use the Defines the name and size of the shared memory zone that stores the group's configuration and runtime state, shared between worker processes. Multiple groups can use the same zone. In this case, it is sufficient to specify the size only once. Added in version 1.10.0: PRO The directive enables the ability to start server selection not from the primary group,
but from the active group, i.e., the one where a server was successfully found previously.
If a server cannot be found in the active group for the next request,
and the search moves to the backup group,
this backup group becomes active,
and subsequent requests are first directed to servers in this group. If the Example: If the load balancer switches from primary servers to the backup group,
all subsequent requests are handled by this backup group for 2 minutes.
After 2 minutes expire, the load balancer re-checks the primary servers
and makes them active again if they are working normally. Added in version 1.7.0: PRO Default — upstream Enables a feedback-based load balancing mechanism for the The following parameters can be specified: The variable from which the feedback value is taken.
It should represent a performance or health metric;
it is assumed to be provided by the server. The value is evaluated with each response from the server
and factored into the moving average
according to If the parameter is set, the feedback value is interpreted inversely:
lower values indicate better performance. The factor by which the feedback value is weighted
when calculating the average.
Valid values are integers from 0 to 99.
Default is The average is calculated using the exponential smoothing formula. The larger the factor, the less new values affect the average;
if Specifies a condition variable
that controls how connections are accounted for in the calculation.
The average value is updated with the feedback value
only if the condition variable
is not equal to Note By default, traffic from probes
is not included in the calculation;
combining the $upstream_probe variable
with Example: This configuration categorizes servers by feedback levels
based on protocols used in individual sessions,
and also adds a condition on $upstream_probe
to account only for Specifies a load balancing method for the group where client-server mapping is determined using a hashed key value. The key can contain text, variables, and their combinations. Usage example: The method is compatible with the Perl Cache::Memcached library. If the Specifies a load balancing method for the group where a connection is passed to the server with the least number of active connections, taking into account server weights. If several servers are suitable, they are selected cyclically (round-robin) with their weights taken into account. Default — upstream Specifies a load balancing method for the group where the probability of passing
a connection to an active server is inversely proportional to its average
response time; the smaller it is, the more connections the server will receive. The directive accounts for the average connection establishment time. The directive uses the average time to receive the first byte of the response. The directive uses the average time to receive the complete response. Added in version 1.7.0: PRO Serves the same function as response_time_factor (PRO)
and overrides it if the parameter is set. Specifies a condition variable
that controls which connections are accounted for in the calculation.
The average value is updated
only if the connection's condition variable
is not equal to Note By default, probes
are not included in the calculation;
combining the $upstream_probe variable
with The current values are presented as Specifies a load balancing method for the group where a connection is passed to a randomly selected server, taking into account server weights. If the optional Sets the smoothing factor for the least_time (PRO) load balancing method,
using the previous value when calculating the average response time
according to the exponential weighted moving average formula. The larger the specified number, the less new values influence the average;
if The respective moving averages are presented as Note Only successful responses are considered in the calculation;
what constitutes an unsuccessful response
is determined by the proxy_next_upstream directives. Added in version 1.6.0: Angie Added in version 1.6.0: Angie PRO Default — upstream Configures the binding of client sessions to proxied servers
in the mode specified by the first parameter;
to drain requests from servers
that have the Attention The This mode uses predefined route identifiers
that can be embedded in connection properties accessible to Angie.
It is less flexible because it relies on predefined values
but is better suited if such identifiers are already in use. Here, when establishing a connection, the proxied server
can assign a route to the client and return its identifier
in a manner known to both.
The value of the sid parameter
of the server directive
must be used as the route identifier.
Note that the parameter is additionally hashed
if the sticky_secret directive is set. Subsequent connections from clients wishing to use this route
must contain the server-issued identifier in a way
that ensures it ends up in Angie variables. The directive parameters specify variables for routing.
To select the server where the incoming connection is routed,
the first non-empty variable is used;
it is then compared with the sid parameter
of the server directive.
If selecting a server fails
or the chosen server cannot accept the connection,
another server is selected
according to the configured balancing method. Here,
Angie looks for the route identifier in the This mode uses a dynamically generated key
to bind a client to a specific proxied server;
it is more flexible
because it assigns servers on the fly,
stores sessions in a shared memory zone,
and supports various ways of passing session identifiers. Here, a session is created
based on connection properties from the proxied server.
The The session identifier is the value of the first non-empty variable
specified with Sessions are stored in a shared memory zone;
its name and size are set by the By default, Angie extends the session lifetime,
updating the last access timestamp with each use.
The Subsequent connections from clients wishing to use the session
must contain its identifier
in a way that ensures it ends up in a non-empty variable
specified with The In the example, Angie creates and looks up sessions
using the $rdp_cookie variable: The Angie relies entirely on the remote store:
it does not cache sessions locally
(although it allows caching store responses via The The store receives the session identifier from On the Angie side, two special variables are provided for this:
$sticky_sessid and $sticky_sid, respectively.
Note If Additionally, in this case, the A 200 response from the remote store
indicates that it has accepted the session
and stored it with the proposed values for future use. A 409 response from the remote store
indicates that the given session identifier already exists.
In this case, the response must contain an alternative session identifier
in the Below is a simplified configuration example.
The remote store returns the session identifier in the Added in version 1.6.0: Angie Added in version 1.6.0: Angie PRO When enabled, causes Angie to return a connection error to the client
if the desired server is unavailable,
instead of using any other available server
as it would when no servers in the group are available. Added in version 1.6.0: Angie Added in version 1.6.0: Angie PRO Adds the string as salt to the MD5 hashing function
for the sticky directive in Salt is appended after the hashed value;
to independently verify the hashing mechanism: The Used with Used with stores the IP address and port, or the path to the UNIX domain socket of the upstream server. If several servers were contacted during request processing, their addresses are separated by commas, e.g.: 192.168.1.1:1935, 192.168.1.2:1935, unix:/tmp/sock If a server cannot be selected, the variable keeps the name of the server group. number of bytes received from an upstream server. Values from several connections are separated by commas and colons like addresses in the $upstream_addr variable. number of bytes sent to an upstream server. Values from several connections are separated by commas and colons like addresses in the $upstream_addr variable. time to connect to the upstream server; the time is kept in seconds with millisecond resolution. Times of several connections are separated by commas and colons like addresses in the $upstream_addr variable. time to receive the first byte of data; the time is kept in seconds with millisecond resolution. Times of several connections are separated by commas like addresses in the $upstream_addr variable. session duration in seconds with millisecond resolution. Times of several connections are separated by commas like addresses in the $upstream_addr variable. Status of sticky connections. Connection routed to upstream without sticky enabled. Connection without sticky information. Connection with sticky information routed to the desired backend. Connection with sticky information routed to the backend
selected by the load balancing algorithm. Values from multiple connections are separated by commas and colons,
similar to addresses in the $upstream_addr variable.Configuration Example#
upstream backend {
hash $remote_addr consistent;
zone backend 1m;
server backend1.example.com:1935 weight=5;
server unix:/tmp/backend3;
server backend3.example.com service=_example._tcp resolve;
server backup1.example.com:1935 backup;
server backup2.example.com:1935 backup;
}
resolver 127.0.0.53 status_zone=resolver;
server {
listen 1936;
proxy_pass backend;
}
Directives#
upstream#
upstream backend {
server backend1.example.com:1935 weight=5;
server 127.0.0.1:1935 max_fails=3 fail_timeout=30s;
server unix:/tmp/backend2;
server backend3.example.com:1935 resolve;
server backup1.example.com:1935 backup;
}
server#
unix:
prefix. A domain name that resolves to several IP addresses defines multiple servers at once.weight=
numbermax_conns=
number0
, meaning there is no limit. If the server group does not reside in the shared memory, the limitation works per each worker process.max_fails=
number — sets the number of unsuccessful attempts
to communicate with the server
that should happen in the duration set by fail_timeout
to consider the server unavailable;
it is then retried after the same duration.server
directive in a group resolves into multiple servers,
its max_fails
setting applies to each server individually.server
directives are resolved,
the max_fails
setting has no effect and will be ignored.max_fails=1
max_fails=0
fail_timeout=
time — sets the period of time during which a specified number of
unsuccessful attempts to communicate with the server (max_fails) should happen to consider the server unavailable.
The server then remains unavailable for the same amount of time
before it is retried.server
directive in a group resolves into multiple servers,
its fail_timeout
setting applies to each server individually.server
directives are resolved,
the fail_timeout
setting has no effect and will be ignored.backup
down
drain
(PRO)down
.backup
parameter cannot be used along with the hash and random load balancing methods.down
and drain
parameters are mutually exclusive.resolve
service=
name_
,
then _tcp
is added after a dot.
Thus, the service name http
will result in _http._tcp
.backup
is set with server
,
top-priority SRV records resolve into backup servers,
and other records are ignored.weight
parameter of the server
directive.
If weight is set by both the directive and the SRV record,
the weight set by the directive is used._http._tcp.backend.example.com
record:server backend.example.com service=http resolve;
sid=
idslow_start=
timeserver
is specified in the upstream,
slow_start
has no effect and will be ignored.state (PRO)#
/var/lib/angie/state/
(/var/db/angie/state/
on FreeBSD)
is created with appropriate permissions for storing such files,
so you only need to add the filename in the configuration:upstream backend {
zone backend 1m;
state /var/lib/angie/state/<FILE NAME>;
}
s_server
.
The file contents change whenever servers are modified in the
/config/stream/upstreams/ section
via the configuration API.
The file is read at Angie startup or configuration reload.state
directive in an upstream
block,
there should be no server
directives in it,
but a shared memory zone (zone) is required.zone#
backup_switch (PRO)#
permanent
parameter is defined without a time value,
the group remains active after selection,
and automatic re-checking of groups with lower priority levels does not occur.
If time is specified,
the active status of the group expires after the specified interval,
and the load balancer again checks groups with lower priority levels,
returning to them if the servers are working normally.upstream media_backend {
server primary1.example.com:1935;
server primary2.example.com:1935;
server reserve1.example.com:1935 backup;
server reserve2.example.com:1935 backup;
backup_switch permanent=2m;
}
feedback (PRO)#
feedback
variable [inverse
] [factor=
number] [account=
condition_variable];upstream
.
It dynamically adjusts load balancing decisions
by multiplying each proxied server's weight by the average feedback value,
which changes over time based on the variable value
and is subject to an optional condition.variable
inverse
and factor
settings.inverse
factor
90
.90
is specified, 90% of the previous value will be taken
and only 10% of the new value.account
""
or "0"
.account
allows including them
or even excluding everything else.upstream backend {
zone backend 1m;
feedback $feedback_value factor=80 account=$condition_value;
server backend1.example.com:1935 weight=1;
server backend2.example.com:1935 weight=2;
}
map $protocol $feedback_value {
"TCP" 100;
"UDP" 75;
default 10;
}
map $upstream_probe $condition_value {
"high_priority" "1";
"low_priority" "0";
default "1";
}
high_priority
probes
or regular client sessions.hash#
hash $remote_addr;
consistent
parameter is specified, the ketama consistent hashing method will be used instead of the above method. The method ensures that when a server is added to or removed from the group, only a minimal number of keys will be remapped to other servers. Using the method for caching servers provides a higher cache hit ratio. The method is compatible with the Perl Cache::Memcached::Fast library with the ketama_points parameter set to 160.least_conn#
least_time (PRO)#
least_time
connect
| first_byte
| last_byte
[factor=
number] [account=
condition_variable];connect
first_byte
last_byte
factor
account
""
or "0"
.account
allows including them
or even excluding everything else.connect_time
, first_byte_time
,
and last_byte_time
in the server's health
object
among the upstream metrics in the API.random#
two
parameter is specified, Angie randomly selects two servers and then chooses a server using the specified method. The default method is least_conn, which passes a connection to the server with the least number of active connections.response_time_factor (PRO)#
90
is specified, 90% of the previous value will be taken,
and only 10% of the new value. Valid values range from 0 to 99 inclusive.connect_time
(connection
establishment time), first_byte_time
(time to receive the first
byte of the response), and last_byte_time
(time to receive the complete
response) in the server's health
object among the stream
upstream metrics in the API.sticky#
sticky route
$variable...;sticky learn
zone=
zone create=
$create_var1... lookup=
$lookup_var1... [connect
] [norefresh
] [timeout=
time];sticky learn
lookup=
$lookup_var1... remote_action=
uri remote_result=
$remote_var;sticky
directive configured,
use the drain
option (PRO) in the server block.sticky
directive must be used after all directives
that set the load balancing method;
otherwise, it won't work.$route
variable,
which gets its value based on $ssl_preread_server_name
(note that ssl_preread must be enabled):stream {
map $ssl_preread_server_name $route {
a.example.com a;
b.example.com b;
default "";
}
upstream backend {
server 127.0.0.1:8081 sid=a;
server 127.0.0.1:8082 sid=b;
sticky route $route;
}
server {
listen 127.0.0.1:8080;
ssl_preread on;
proxy_pass backend;
}
}
create
and lookup
parameters list variables
indicating how new sessions are created
and existing sessions are looked up.
Both parameters can be used multiple times.create
;
for example, this could be the
name of the proxied server.zone
parameter.
If a session has been inactive for the time
specified by timeout
, it is deleted.
The default is 1 hour.norefresh
parameter disables this behavior:
the session will expire strictly by timeout, even if it continues to be used.
This mode is useful
when forced session termination after a time period is required,
for example, when integrating with external session managers.lookup
;
its value will then be matched against sessions in shared memory.
If selecting a server fails
or the chosen server cannot handle the connection,
another server is selected
according to the configured balancing method.connect
parameter allows creating a session
immediately after receiving response headers from the proxied server.
Without it, a session is created only after connection processing is complete.stream {
upstream backend {
server 127.0.0.1:3390 sid=a;
server 127.0.0.1:3391 sid=b;
sticky learn lookup=$rdp_cookie create=$rdp_cookie zone=sessions:1m;
}
server {
listen 127.0.0.1:3389;
ssl_preread on;
proxy_pass backend;
}
}
remote_action
and remote_result
parameters
allow dynamic assignment of session identifiers and their management
using a remote session store.proxy_cache
)
and sends a separate request to the remote store every time
a session needs to be retrieved or created.remote_action
parameter specifies the URI of the remote store,
which should handle session lookup and creation as follows:lookup
and the locally proposed server identifier
associated with this session via custom headers
or another method.sticky_sid
contains the value of the sid=
parameter
from the server
directive in the upstream block, if set,
or the MD5 hash of the server name.remote_action
points to a location
in the client context,
variables are automatically exported to the HTTP context with the
stream_
prefix (e.g., $stream_sticky_sessid
,
$stream_sticky_sid
).
This allows direct use in HTTP directives
without additional configuration.remote_uri
parameter applies,
specifying the URI of the client HTTP request to the specified location
.
By default, it equals /create
.X-Sticky-Sid
header.
Angie stores this identifier in the variable
specified by the remote_result
parameter.X-Sid
header
and thus confirms or overrides Angie's choice:http {
client {
location @sticky_client1 {
# use variables from the stream upstream;
# it adds these variables to the HTTP context with the stream_* prefix
proxy_set_header X-Sticky-Sessid $stream_sticky_sessid;
proxy_set_header X-Sticky-Sid $stream_sticky_sid;
proxy_set_header X-Sticky-Last $msec;
proxy_pass http://127.0.0.1:8080;
proxy_cache remote;
proxy_cache_valid 200 1d;
proxy_cache_key $scheme$proxy_host$request_uri$stream_sticky_sessid;
}
}
}
stream {
upstream u {
server 127.0.0.1:8081;
server 127.0.0.1:8082;
sticky learn lookup=$remote_addr # stream variable
remote_action=@sticky_client1 # location from client block
remote_result=$upstream_http_x_sid # HTTP variable
remote_uri=/foo; # default is /create
}
server {
listen 127.0.0.1:8080;
proxy_pass u;
}
}
sticky_strict#
sticky_secret#
route
mode.
The string may contain variables, for example, $remote_addr:upstream backend {
server 127.0.0.1:8081 sid=a;
server 127.0.0.1:8082 sid=b;
sticky route $route;
sticky_secret my_secret.$remote_addr;
}
$ echo -n "<VALUE><SALT>" | md5sum
Built-in Variables#
stream_upstream
module supports the following built-in variables:$sticky_sessid
#remote_action
in sticky;
stores the initial session identifier taken from lookup
.$sticky_sid
#remote_action
in sticky;
stores the server identifier previously associated with the session.sticky_sid
contains the value of the sid=
parameter
from the server
directive in the upstream block, if specified,
or the MD5 hash of the server name.$upstream_addr
#$upstream_bytes_received
#$upstream_bytes_sent
#$upstream_connect_time
#$upstream_first_byte_time
#$upstream_session_time
#$upstream_sticky_status
#""
NEW
HIT
MISS