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add ability to prefix log lines with a.. prefix. #15

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add ability to prefix log lines with a.. prefix. #15

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3 changes: 2 additions & 1 deletion lib/logstasher.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ class << self
attr_writer :serialize_parameters
attr_writer :silence_standard_logging
attr_accessor :metadata
attr_accessor :prefix

def append_fields(&block)
@append_fields_callback = block
Expand Down Expand Up @@ -57,7 +58,7 @@ def log_as_json(payload, as_logstash_event: false)
payload.to_json
end

logger << json_payload + $INPUT_RECORD_SEPARATOR
logger << (prefix.nil? ? "" : prefix) + json_payload + $INPUT_RECORD_SEPARATOR
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prefix.to_s will work here since nil.to_s #=> "".

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@film42 film42 Nov 10, 2022 •
edited
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This might actually be a bit problematic since the expectation is that the output is a pure json blob without any formatting or parsing required.

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the idea we were discussing was that prefixing the blob with a prefix would allow us to positively identify logstasher output in a stdout stream without having to fully parse the json

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Won't this break logstash filters that try to parse a json payload?

    filter {
      json {
        source => "message"
      }
    }

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if someone defines a prefix then the logstash pipeline will extract the json string after the prefix to a field and then json parse on that new field.

end

def logger
Expand Down
2 changes: 2 additions & 0 deletions lib/logstasher/railtie.rb
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Expand Up @@ -10,6 +10,7 @@ class Railtie < ::Rails::Railtie
config.logstasher.log_level = ::Logger::INFO

config.logstasher.metadata = {}
config.logstasher.prefix = ""
config.before_initialize do
options = config.logstasher

Expand All @@ -20,6 +21,7 @@ class Railtie < ::Rails::Railtie
::LogStasher.logger = options.logger || default_logger
::LogStasher.logger.level = options.log_level
::LogStasher.metadata = options.metadata
::LogStasher.prefix = options.prefix
end

initializer 'logstasher.load' do
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13 changes: 13 additions & 0 deletions spec/lib/logstasher/logstasher_spec.rb
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Expand Up @@ -24,6 +24,19 @@
end
end

context "with prefix" do
before { ::LogStasher.prefix = "LOGSTASHER " }
after { ::LogStasher.prefix = nil }

it "appends a prefix to log lines." do
expect(::LogStasher.logger).to receive(:<<) do |line|
expect(line).to match(/^LOGSTASHER /)
end

::LogStasher.log_as_json(:yolo => :brolo)
end
end

context "with metadata" do
before { ::LogStasher.metadata = { :namespace => :cooldude } }
after { ::LogStasher.metadata = {} }
Expand Down