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pubsub: Lua Pubsub client driver for nginx-module-lua based on the cosocket API


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CentOS/RHEL 7 or Amazon Linux 2

yum -y install
yum -y install lua-resty-pubsub

CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023

yum -y install
yum -y install lua5.1-resty-pubsub

To use this Lua library with NGINX, ensure that nginx-module-lua is installed.

This document describes lua-resty-pubsub v1.4 released on Apr 17 2021.

Lua Pubsub client driver for the ngx_lua based on the cosocket API.

lua module lua module License


This Lua library is a Pubsub client driver for the ngx_lua nginx module:

This Lua library takes advantage of ngx_lua's cosocket API, which ensures 100% nonblocking behavior. This library pushes messages (with attributes) to Google Cloud pubsub using nginx timers and http requests.

Note that at least ngx_lua 0.9.3 or ngx_openresty is required, and unfortunately only LuaJIT supported (--with-luajit).


    server {
        location = /publish {
            resolver ipv6=off;

            content_by_lua_block {
                local cjson = require "cjson"
                local pubsub_producer = require "resty.pubsub.producer"
                local OAUTH_TOKEN = ngx.shared.OAUTH_TOKEN -- A different dictionary can also be provided

                -- A callback which will recieve messages if gets successfully sent
                -- Types of messages & err are a table
                local success_callback = function (topic, err, messages)
                    ngx.log(ngx.INFO, "Messages: ", cjson.encode(messages), " successfully pushed to topic: ", topic)

                -- A callback which will recieve messages if gets failed
                -- Types of messages & err are a table
                local error_callback = function (topic, err, messages)
                    for _, message in ipairs(messages) do
                        ngx.log(ngx.ERR, "Failed to send Message : ", cjson.encode(message), " with err: ", cjson.encode(err))

                local publish = function()

                    -- Pubsub Producer Config
                    local pubsub_config = {
                        project_id = "demo-project",
                        topic = "demo-topic",
                        pubsub_base_domain = "",
                        pubsub_base_port = 443,
                        is_emulator = false,
                        producer_config = {
                            max_batch_size = 200, -- number of packets
                            max_buffering = 5000, -- max number of packets in buffer
                            timer_interval = 10000, -- in milliseconds
                            last_flush_interval = 5000, -- in milliseconds
                            http_timeout = 6000, -- in milliseconds
                            keepalive_max_idle_timeout = 2000, -- in milliseconds
                            keepalive_pool_size = 50
                        oauth_config = {
                            service_account_key_path = "/etc/key.json", -- Replace this with your own key path
                            oauth_base_uri = "",
                            oauth_scopes = {
                            oauth_token_dict = OAUTH_TOKEN
                        success_callback = success_callback,
                        error_callback = error_callback

                    -- Create the producer object
                    -- No matter how many times you call new, the producer instance will always be generated once per topic per worker process
                    local producer, err = pubsub_producer:new(pubsub_config)

                    -- Also check if there is any error while initializing producer
                    if err ~= nil then
                        ngx.log(ngx.ERR, "Unable to create pubsub producer ", err)

                    -- Finally send the message with attributes.
                    local ok, send_err = producer:send("Some Random Text", {
                        attr1 = "Test1",
                        attr2 = "Test2"

                    -- Also check if there is any error while sending message
                    if send_err ~= nil then
                        ngx.log(ngx.ERR, "Unable to send data to pubsub: ", send_err)


                -- Publish Message



Producer Configs

Property Data Type Description Default Value
project_id string Specifies the project id as a string of your Pub/Sub project none (Required)
topic string Specifies the topic in which the data needs to be send none (Required)
pubsub_base_domain string Specifies the base domain through which the http connection is made.
pubsub_base_port number Specifies the base domain port through which the http connection is made. 443
is_emulator boolean Specifies a boolean value. true if you are communicating with. false
producer_config.max_batch_size number Specifies the max batch size that will be pushed to pubsub. 200
producer_config.max_buffering number Specifies the max size of the buffer which will hold the data for a specific duration of time. 5000
producer_config.timer_interval number (milliseconds) Specifies the time interval in which the stale messages in buffer are checked for publishing. 10000
producer_config.last_flush_interval number (milliseconds) Specifies the max interval between the last flush time and current time. Used when packets in buffer are less than the batch size for a longer period of time. 10000
producer_config.http_timeout number (milliseconds) Sets the timeout protection for subsequent operations, including the connect method. 5000
producer_config.keepalive_max_idle_timeout number (milliseconds) Used in httpc:set_keepalive which attempts to puts the current connection into the ngx_lua cosocket connection pool. 2000
producer_config.keepalive_pool_size number Used in httpc:set_keepalive which attempts to puts the current connection into the ngx_lua cosocket connection pool. 50
oauth_config.service_account_key_path string Specifies the path for service account key that are used to authenticate to pub/sub project. none (Required)
oauth_config.oauth_base_uri string Specifies the base uri to which request is made to Google authorization server for a token that will be used in subsequent requests.
oauth_config.oauth_scopes list of string Specifies a table comprising of OAuth 2.0 scopes that you might need to request to access Google APIs, depending on the level of access you need. {""}
oauth_config.oauth_token_dict lua_shared_dict Specifies a shared memory zone across workers, to serve as a storage for the oauth token. ngx.shared.OAUTH_TOKEN
success_handler function This is a callback function which will be provided with all the messages with their attributes which are successfully pushed to pubsub. none (Optional)
error_handler function This is a callback function which will be executed when a batch fails. none (Optional)



To load this module, just do this

    local producer = require "resty.pubsub.producer"



syntax: local p, err = producer:new(pubsub_config)


syntax: p:send(message, attributes)

  • Requires a message of type string and attributes of type table


  1. Pubsub Message Fetch API
  2. Add Unit Test Cases

See Also


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