pubsub: Lua Pubsub client driver for nginx-module-lua based on the cosocket API
Installation
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CentOS/RHEL 7 or Amazon Linux 2
yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install lua-resty-pubsub
CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023
yum -y install https://extras.getpagespeed.com/release-latest.rpm
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.
Description
This Lua library is a Pubsub client driver for the ngx_lua nginx module: http://wiki.nginx.org/HttpLuaModule
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 1.4.3.7 is required, and unfortunately only LuaJIT supported (--with-luajit).
Synopsis
server {
location = /publish {
resolver 8.8.8.8 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)
end
-- 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))
end
end
local publish = function()
-- Pubsub Producer Config
local pubsub_config = {
project_id = "demo-project",
topic = "demo-topic",
pubsub_base_domain = "pubsub.googleapis.com",
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 = "https://www.googleapis.com/oauth2/v4/token",
oauth_scopes = {
"https://www.googleapis.com/auth/pubsub"
},
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)
return
end
-- 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)
return
end
end
-- Publish Message
publish()
}
}
}
Configs
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.googleapis.com |
| 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. | https://www.googleapis.com/oauth2/v4/token |
| 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. | {"https://www.googleapis.com/auth/pubsub"} |
| 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) |
Modules
resty.pubsub.producer
To load this module, just do this
local producer = require "resty.pubsub.producer"
Methods
new
syntax: local p, err = producer:new(pubsub_config)
send
syntax: p:send(message, attributes)
- Requires a message of type string and attributes of type table
See Also
- the ngx_lua module: http://wiki.nginx.org/HttpLuaModule
GitHub
You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-pubsub.