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lua-upstream: Lua API for NGINX upstream control

Installation

You can install this module in any RHEL-based distribution, including, but not limited to:

  • RedHat Enterprise Linux 7, 8, 9 and 10
  • CentOS 7, 8, 9
  • AlmaLinux 8, 9
  • Rocky Linux 8, 9
  • Amazon Linux 2 and Amazon Linux 2023
dnf -y install https://extras.getpagespeed.com/release-latest.rpm
dnf -y install nginx-module-lua-upstream

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm
yum -y install nginx-module-lua-upstream

Enable the module by adding the following at the top of /etc/nginx/nginx.conf:

load_module modules/ngx_http_lua_upstream_module.so;

This document describes nginx-module-lua-upstream v0.7 released on May 15 2017.

http {
    upstream foo.com {
        server 127.0.0.1 fail_timeout=53 weight=4 max_fails=100;
        server agentzh.org:81;
    }

    upstream bar {
        server 127.0.0.2;
    }

    server {
        listen 8080;

        # sample output for the following /upstream interface:
        # upstream foo.com:
        #     addr = 127.0.0.1:80, weight = 4, fail_timeout = 53, max_fails = 100
        #     addr = 106.184.1.99:81, weight = 1, fail_timeout = 10, max_fails = 1
        # upstream bar:
        #     addr = 127.0.0.2:80, weight = 1, fail_timeout = 10, max_fails = 1

        location = /upstreams {
            default_type text/plain;
            content_by_lua_block {
                local concat = table.concat
                local upstream = require "ngx.upstream"
                local get_servers = upstream.get_servers
                local get_upstreams = upstream.get_upstreams

                local us = get_upstreams()
                for _, u in ipairs(us) do
                    ngx.say("upstream ", u, ":")
                    local srvs, err = get_servers(u)
                    if not srvs then
                        ngx.say("failed to get servers in upstream ", u)
                    else
                        for _, srv in ipairs(srvs) do
                            local first = true
                            for k, v in pairs(srv) do
                                if first then
                                    first = false
                                    ngx.print("    ")
                                else
                                    ngx.print(", ")
                                end
                                if type(v) == "table" then
                                    ngx.print(k, " = {", concat(v, ", "), "}")
                                else
                                    ngx.print(k, " = ", v)
                                end
                            end
                            ngx.print("\n")
                        end
                    end
                end
            }
        }
    }
}

Functions

get_upstreams

syntax: names = upstream.get_upstreams()

Get a list of the names for all the named upstream groups (i.e., explicit upstream {} blocks).

Note that implicit upstream groups created by proxy_pass and etc are excluded.

get_servers

syntax: servers = upstream.get_servers(upstream_name)

Get configurations for all the servers in the specified upstream group. Please one server may take multiple addresses when its server name can be resolved to multiple addresses.

The return value is an array-like Lua table. Each table entry is a hash-like Lua table that takes the following keys:

  • addr

    socket address(es). can be either a Lua string or an array-like Lua table of Lua strings. * backup * fail_timeout * max_fails * name * weight

get_primary_peers

syntax: peers = upstream.get_primary_peers(upstream_name)

Get configurations for all the primary (non-backup) peers in the specified upstream group.

The return value is an array-like Lua table for all the primary peers. Each table entry is a (nested) hash-like Lua table that takes the following keys:

  • current_weight
  • effective_weight
  • fail_timeout
  • fails

  • id

    Identifier (ID) for the peer. This ID can be used to reference a peer in a group in the peer modifying API. * max_fails * name

    Socket address for the current peer * weight * accessed

    Timestamp for the last access (in seconds since the Epoch) * checked

    Timestamp for the last check (in seconds since the Epoch) * down

    Holds true if the peer has been marked as "down", otherwise this key is not present * conns

    Number of active connections to the peer (this requires NGINX 1.9.0 or above).

get_backup_peers

syntax: peers = upstream.get_backup_peers(upstream_name)

Get configurations for all the backup peers in the specified upstream group.

The return value has the same structure as get_primary_peers function.

set_peer_down

syntax: ok, err = upstream.set_peer_down(upstream_name, is_backup, peer_id, down_value)

Set the "down" (boolean) attribute of the specified peer.

To uniquely specify a peer, you need to specify the upstream name, whether or not it is a backup peer, and the peer id (starting from 0).

Note that this method only changes the peer settings in the current Nginx worker process. You need to synchronize the changes across all the Nginx workers yourself if you want a server-wide change (for example, by means of ngx_lua's ngx.shared.DICT).

Below is an example. Consider we have a "bar" upstream block in nginx.conf:

upstream bar {
    server 127.0.0.2;
    server 127.0.0.3 backup;
    server 127.0.0.4 fail_timeout=23 weight=7 max_fails=200 backup;
}

then

upstream.set_peer_down("bar", false, 0, true)

will turn down the primary peer corresponding to server 127.0.0.2.

Similarly,

upstream.set_peer_down("bar", true, 1, true)

will turn down the backup peer corresponding to server 127.0.0.4 ....

You can turn on a peer again by providing a false value as the 4th argument.

current_upstream_name

syntax: name = upstream.current_upstream_name()

Returns the name of the proxied upstream for the current request. If there is no upstream for this request (no proxy_pass call), or this function is called in a phase prior to the content phase, then the return value will be nil. If a port is explicitly included in the upstream definition or proxy_pass directive, it will be included in the return value of this function.

Example:

-- upstream my_upstream { ... }
-- proxy_pass http://my_upstream;
upstream.current_upstream_name() --> my_upstream

-- proxy_pass http://example.com:1234;
upstream.current_upstream_name() --> example.com:1234

Note that implicit upstreams created by proxy_pass are included, contrary to the output of upstream.get_upstreams().

assuming your luajit is installed to /opt/luajit:

export LUAJIT_LIB=/opt/luajit/lib

assuming you are using LuaJIT v2.1:

export LUAJIT_INC=/opt/luajit/include/luajit-2.1

Here we assume you would install you nginx under /opt/nginx/.

./configure --prefix=/opt/nginx \ --with-ld-opt="-Wl,-rpath,$LUAJIT_LIB" \ --add-module=/path/to/lua-nginx-module \ --add-module=/path/to/lua-upstream-nginx-module

make -j2 make install 

Starting from NGINX 1.9.11, you can also compile this module as a dynamic module, by using the `--add-dynamic-module=PATH` option instead of `--add-module=PATH` on the
`./configure` command line above. And then you can explicitly load the module in your `nginx.conf` via the [load_module](http://nginx.org/en/docs/ngx_core_module.html#load_module)
directive, for example,

```nginx
load_module /path/to/modules/ngx_http_lua_upstream_module.so;

See Also

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-lua-upstream.