batch-processor.md

title
Batch Processor

The batch processor can be used to aggregate entries(logs/any data) and process them in a batch. When the batch_max_size is set to 1 the processor will execute each entry immediately. Setting the batch max size more than 1 will start aggregating the entries until it reaches the max size or the timeout expires.

Configurations

The only mandatory parameter to create a batch processor is a function. The function will be executed when the batch reaches the max size or when the buffer duration exceeds.

Name	Type	Requirement	Default	Valid	Description
name	string	optional	logger's name	["http logger",...]	A unique identifier used to identify the batch processor, which defaults to the name of the logger plug-in that calls the batch processor, such as plug-in "http logger" 's name is "http logger.
batch_max_size	integer	optional	1000	[1,...]	Sets the maximum number of logs sent in each batch. When the number of logs reaches the set maximum, all logs will be automatically pushed to the HTTP/HTTPS service.
inactive_timeout	integer	optional	5	[1,...]	The maximum time to refresh the buffer (in seconds). When the maximum refresh time is reached, all logs will be automatically pushed to the HTTP/HTTPS service regardless of whether the number of logs in the buffer reaches the maximum number set.
buffer_duration	integer	optional	60	[1,...]	Maximum age in seconds of the oldest entry in a batch before the batch must be processed.
max_retry_count	integer	optional	0	[0,...]	Maximum number of retries before removing the entry from the processing pipeline when an error occurs.
retry_delay	integer	optional	1	[0,...]	Number of seconds the process execution should be delayed if the execution fails.

The following code shows an example of how to use batch processor in your plugin:

local bp_manager_mod = require("apisix.utils.batch-processor-manager")
...

local plugin_name = "xxx-logger"
local batch_processor_manager = bp_manager_mod.new(plugin_name)
local schema = {...}
local _M = {
    ...
    name = plugin_name,
    schema = batch_processor_manager:wrap_schema(schema),
}

...


function _M.log(conf, ctx)
    local entry = {...} -- data to log

    if batch_processor_manager:add_entry(conf, entry) then
        return
    end
    -- create a new processor if not found

    -- entries is an array table of entry, which can be processed in batch
    local func = function(entries)
        -- serialize to json array core.json.encode(entries)
        -- process/send data
        return true
        -- return false, err_msg, first_fail if failed
        -- first_fail(optional) indicates first_fail-1 entries have been successfully processed
        -- and during processing of entries[first_fail], the error occurred. So the batch processor
        -- only retries for the entries having index >= first_fail as per the retry policy.
    end
    batch_processor_manager:add_entry_to_new_processor(conf, entry, ctx, func)
end

The batch processor's configuration will be set inside the plugin's configuration. For example:

:::note You can fetch the admin_key from config.yaml and save to an environment variable with the following command:

admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')

:::

curl http://127.0.0.1:9180/apisix/admin/routes/1 -H "X-API-KEY: $admin_key" -X PUT -d '
{
      "plugins": {
            "http-logger": {
                "uri": "http://mockbin.org/bin/:ID",
                "batch_max_size": 10,
                "max_retry_count": 1
            }
       },
      "upstream": {
           "type": "roundrobin",
           "nodes": {
               "127.0.0.1:1980": 1
           }
      },
      "uri": "/hello"
}'

If your plugin only uses one global batch processor, you can also use the processor directly:

local entry = {...} -- data to log
if log_buffer then
    log_buffer:push(entry)
    return
end

local config_bat = {
    name = config.name,
    retry_delay = config.retry_delay,
    ...
}

local err
-- entries is an array table of entry, which can be processed in batch
local func = function(entries)
    ...
    return true
    -- return false, err_msg, first_fail if failed
end
log_buffer, err = batch_processor:new(func, config_bat)

if not log_buffer then
    core.log.warn("error when creating the batch processor: ", err)
    return
end

log_buffer:push(entry)

Note: Please make sure the batch max size (entry count) is within the limits of the function execution. The timer to flush the batch runs based on the inactive_timeout configuration. Thus, for optimal usage, keep the inactive_timeout smaller than the buffer_duration.