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--[[
This Lua script provides 3 interfaces or callbacks for filter_lua:
- cb_print => Print records to the standard output
- cb_drop => Drop the record
- cb_replace => Replace record content with a new table
The key inside each function is to do a proper handling of the
return values. Each function must return 3 values:
return code, timestamp, record
where:
- code : -1 record must be deleted
0 record not modified, keep the original
1 record was modified, replace timestamp and record.
2 record was modified, replace record and keep timestamp.
- timestamp: Unix timestamp with precision (double)
- record : Table with multiple key/val
Uppon return if code == 1 (modified), then filter_lua plugin
will replace the original timestamp and record with the returned
values. If code == 0 the original record is kept otherwise if
code == -1, the original record will be deleted.
]]
-- Print record to the standard output
function cb_print(tag, timestamp, record)
output = tag .. ": [" .. string.format("%f", timestamp) .. ", { "
for key, val in pairs(record) do
output = output .. string.format(" %s => %s,", key, val)
end
output = string.sub(output,1,-2) .. " }]"
print(output)
-- Record not modified so 'code' return value is 0 (first parameter)
return 0, 0, 0
end
-- Drop the record
function cb_drop(tag, timestamp, record)
return -1, 0, 0
end
-- Compose a new JSON map and report it
function cb_replace(tag, timestamp, record)
-- Record modified, so 'code' return value (first parameter) is 1
new_record = {}
new_record["new"] = 12345
new_record["old"] = record
return 1, timestamp, new_record
end
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