Custom Go Plugin for Jaeger

Note: This plugin is under heavily development.

This plugin implements Jaeger Remote Sampling protocol on Golang cutom plugin mechanism.

Prerequisites

• Golang 1.23.0 or later

Building

$ go mod download
<snip>
$ make

Then, the c-shared object will be created as:

ls *.so
custom_jeager_remote.so

Configuration

For specifying the place of plugin’s shared object, we need to specify the path in plugin.yaml:

plugins:
    - /path/to/custom_jeager_remote.so

For custom jeager plugin, we need to add custom section in fluent-bit conf:

Basic structure

With ini format:

[CUSTOM]
    # The name registered in the Go code ("jaeger_remote")
    Name         jaeger_remote

    # --- Mode Selection ---
    # Can be: "client", "server", or "all" (default)
    Mode         all

    # --- Add parameters for the selected mode below ---

With Yaml format:

customs:
  - name:                jaeger_remote
    # --- Mode Selection ---
    # Can be: "client", "server", or "all" (default)
    mode:                all

    # --- Add parameters for the selected mode below ---

Mode: client

In this mode, the plugin acts as an OpenTelemetry client, fetching sampling strategies from an external server.

With ini format:

[CUSTOM]
    Name                jaeger_remote
    Mode                client

    # URL of the OTLP-compatible collector to send traces to.
    client.server_url   http://localhost:4318

    # URL of the Jaeger-compatible sampling server.
    client.sampling_url http://localhost:5778/sampling

With Yaml format:

customs:
  - name:                jaeger_remote
    mode:                client

    # URL of the OTLP-compatible collector to send traces to.
    client.server_url:   http://localhost:4318

    # URL of the Jaeger-compatible sampling server.
    client.sampling_url: http://localhost:5778/sampling

Mode: Server

In this mode, the plugin polls a Jaeger Collector for strategies and serves them via its own HTTP and/or gRPC endpoints. You can enable one or both by providing their listen addresses.

With ini format:

[CUSTOM]
    Name                jaeger_remote
    Mode                server

    # --- Connection to Jaeger Collector ---
    server.endpoint      jaeger-collector:14250
    server.service_names frontend,backend,database

    # --- Exposed Endpoints (enable one or both) ---
    server.http.listen_addr 0.0.0.0:8899
    server.grpc.listen_addr 0.0.0.0:9099

    # --- Advanced Connection Settings (Optional) ---
    server.retry.initial_interval 10s
    server.keepalive.time         30s

With Yaml format:

customs:
  - name:                jaeger_remote
    mode:                server

    # --- Connection to Jaeger Collector ---
    server.endpoint:      jaeger-collector:14250
    server.service_names: frontend,backend,database

    # --- Exposed Endpoints (enable one or both) ---
    server.http.listen_addr: 0.0.0.0:8899
    server.grpc.listen_addr: 0.0.0.0:9099

    # --- Advanced Connection Settings (Optional) ---
    server.retry.initial_interval: 10s
    server.keepalive.time:         30s

Mode: server (Local File)

This mode loads a static strategy file and serves it via HTTP and/or gRPC. It does not connect to a remote Jaeger Collector.

With ini format:

[CUSTOM]
    Name                   jaeger_remote
    Mode                   server

    # --- Local Strategy File ---
    server.strategy_file   /path/to/my_strategies.json

    # --- Exposed Endpoints ---
    server.http.listen_addr  0.0.0.0:8899

With Yaml format:

customs:
  - name:                jaeger_remote
    mode:                server

    # --- Local Strategy File ---
    server.strategy_file:   /path/to/my_strategies.json

    # --- Exposed Endpoints ---
    server.http.listen_addr:  0.0.0.0:8899

Mode: All

This mode enables both client and server functionalities simultaneously.

With ini format:

[CUSTOM]
    Name                jaeger_remote
    Mode                all

    # --- Client Parameters ---
    client.server_url   http://localhost:4318
    client.sampling_url http://localhost:5778/sampling

    # --- Server Parameters ---
    server.endpoint      jaeger-collector:14250
    server.service_names frontend,backend,database
    server.http.listen_addr 0.0.0.0:8899
    server.grpc.listen_addr 0.0.0.0:9099

With Yaml format:

customs:
  - name:                jaeger_remote
    mode:                all

    # --- Client Parameters ---
    client.server_url:   http://localhost:4318
    client.sampling_url: http://localhost:5778/sampling

    # --- Server Parameters ---
    server.endpoint:      jaeger-collector:14250
    server.service_names: frontend,backend,database
    server.http.listen_addr: 0.0.0.0:8899
    server.grpc.listen_addr: 0.0.0.0:9099

Parameter Reference

Key	Mode	Description	Default
mode	Global	Sets the operating mode. Can be client, server, or all.	all
Client Settings
client.server_url	client/all	The endpoint URL of the OTLP collector to which traces will be sent.	Required
client.sampling_url	client/all	The URL of the Jaeger-compatible sampling server to poll for strategies.	Required
client.rate	client/all	The sampling period of the sending requests for Jaeger-compatible sampling server	5s
Server Settings
server.endpoint	server/all	The gRPC endpoint of the Jaeger Collector to poll for sampling strategies. Mutually exclusive with server.strategy_file.	Required
server.strategy_file	server/all	Path to a local JSON file containing sampling strategies. Mutually exclusive with server.endpoint.	(Disabled)
server.service_names	server/all	A comma-separated list of service names to fetch strategies for.	Required
server.http.listen_addr	server/all	The address and port for the internal HTTP server to listen on. If empty, the HTTP server is disabled.	(Disabled)
server.grpc.listen_addr	server/all	The address and port for the internal gRPC server to listen on. If empty, the gRPC server is disabled.	(Disabled)
server.headers	server/all	Comma-separated key=value pairs to add as gRPC metadata to requests to the Jaeger Collector.
Server TLS Settings
server.tls.insecure	server/all	If true, TLS certificate verification is skipped when connecting to the Jaeger Collector.	false
server.tls.server_name_override	server/all	Overrides the server name used for TLS validation.
server.tls.ca_file	server/all	Path to the CA certificate file for verifying the Jaeger Collector’s certificate.
server.tls.cert_file	server/all	Path to the client’s TLS certificate file.
server.tls.key_file	server/all	Path to the client’s TLS private key file.
Server Keepalive Settings
server.keepalive.time	server/all	Interval to send keepalive pings to the Jaeger Collector. If not set, keepalive is disabled.	(Disabled)
server.keepalive.timeout	server/all	Time to wait for a keepalive ack before considering the connection dead.	20s
server.keepalive.permit_without_stream	server/all	If true, allows pings to be sent even if there are no active streams.	true
Server Retry Settings
server.retry.initial_interval	server/all	The initial time to wait before retrying a failed connection to the Jaeger Collector.	5s
server.retry.max_interval	server/all	The maximum time to wait between retries.	5m
server.retry.multiplier	server/all	The factor by which the retry interval is multiplied after each failed attempt. Must be > 1.0.	1.5
server.retry.max_retry	server/all	The factor by which the maximum retries after each failed attempt. Must be > 1.0.	10

Run

Put c-chared object in the specified path and run fluent-bit:

$ /path/to/fluent-bit -c fluent-bit.conf
<Fluent Bit starting...>