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Add gzip support #223

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merged 6 commits into from
Aug 2, 2024
Merged

Add gzip support #223

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0a62415
Added encoding support for exposed metrics
Athishpranav2003 Jul 29, 2024
87189d9
Updated readme
Athishpranav2003 Jul 29, 2024
29d0dca
Addressed comments
Athishpranav2003 Aug 1, 2024
08389fd
Added UTs
Athishpranav2003 Aug 1, 2024
d1a545b
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Athishpranav2003 Aug 2, 2024
72e2483
Removed dep
Athishpranav2003 Aug 2, 2024
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1 change: 1 addition & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ More configuration parameters:
- `port`: listen port (default: 24231)
- `metrics_path`: metrics HTTP endpoint (default: /metrics)
- `aggregated_metrics_path`: metrics HTTP endpoint (default: /aggregated_metrics)
- `content_encoding`: encoding format for the exposed metrics (default: identity)
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@Lusitaniae Lusitaniae Jul 29, 2024 •
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usually you'd read Accept-Encoding header from the request to determine how to encode the response

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding

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This is true
But in our case Prometheus server accepts both gzip and identity (it's not specific) so the request header has both in accept encoding. We cannot determine whether we only need compressed or identity. That's why I configured it in server side


When using multiple workers, each worker binds to port + `fluent_worker_id`.
To scrape metrics from all workers at once, you can access http://localhost:24231/aggregated_metrics.
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1 change: 1 addition & 0 deletions fluent-plugin-prometheus.gemspec
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Expand Up @@ -15,6 +15,7 @@ Gem::Specification.new do |spec|

spec.add_dependency "fluentd", ">= 1.9.1", "< 2"
spec.add_dependency "prometheus-client", ">= 2.1.0"
spec.add_dependency "zlib", ">=3.0.0"
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spec.add_development_dependency "bundler"
spec.add_development_dependency "rake"
spec.add_development_dependency "rspec"
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29 changes: 26 additions & 3 deletions lib/fluent/plugin/in_prometheus.rb
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Expand Up @@ -3,6 +3,7 @@
require 'fluent/plugin/prometheus_metrics'
require 'net/http'
require 'openssl'
require 'zlib'

module Fluent::Plugin
class PrometheusInput < Fluent::Plugin::Input
Expand Down Expand Up @@ -32,6 +33,9 @@ class PrometheusInput < Fluent::Plugin::Input
config_param :extra_conf, :hash, default: nil, symbolize_keys: true, deprecated: 'See http helper config'
end

desc 'Content encoding of the exposed metrics, Currently supported encoding is identity, gzip. Ref: https://prometheus.io/docs/instrumenting/exposition_formats/#basic-info'
config_param :content_encoding, :string, default: "identity"
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def initialize
super
@registry = ::Prometheus::Client.registry
Expand All @@ -54,6 +58,8 @@ def configure(conf)

@base_port = @port
@port += fluentd_worker_id

raise "Invalid content encoding for the exposed metrics endpoint" unless @content_encoding="identity" || @content_encoding="gzip"
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end

def multi_workers_ready?
Expand Down Expand Up @@ -184,7 +190,16 @@ def start_webrick
end

def all_metrics
[200, { 'Content-Type' => ::Prometheus::Client::Formats::Text::CONTENT_TYPE }, ::Prometheus::Client::Formats::Text.marshal(@registry)]
body = nil
case @content_encoding
when 'gzip'
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gzip = Zlib::GzipWriter.new(StringIO.new)
gzip << ::Prometheus::Client::Formats::Text.marshal(@registry)
body = gzip.close.string
when 'identity'
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body = ::Prometheus::Client::Formats::Text.marshal(@registry)
end
[200, { 'Content-Type' => ::Prometheus::Client::Formats::Text::CONTENT_TYPE, 'Content-Encoding' => @content_encoding }, body]
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rescue => e
[500, { 'Content-Type' => 'text/plain' }, e.to_s]
end
Expand All @@ -197,8 +212,16 @@ def all_workers_metrics
full_result.add_metrics(resp.body)
end
end

[200, { 'Content-Type' => ::Prometheus::Client::Formats::Text::CONTENT_TYPE }, full_result.get_metrics]
body = nil
case @content_encoding
when 'gzip'
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gzip = Zlib::GzipWriter.new(StringIO.new)
gzip << full_result.get_metrics
body = gzip.close.string
when 'identity'
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body = full_result.get_metrics
end
[200, { 'Content-Type' => ::Prometheus::Client::Formats::Text::CONTENT_TYPE, 'Content-Encoding' => @content_encoding }, body]
rescue => e
[500, { 'Content-Type' => 'text/plain' }, e.to_s]
end
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