Set up template output plugin that writes to a file.

.golangci.yml

@@ -25,7 +25,7 @@ linters-settings:
       - "dupSubExpr"
   goimports:
     # Put imports beginning with prefix after 3rd-party packages.
-    local-prefixes: "github.com/y-scope/clp-ffi-go"
+    local-prefixes: "github.com/y-scope/fluent-bit-clp"
   nakedret:
     # Completely disallow naked returns
     max-func-lines: 0

config/config.go

@@ -0,0 +1,74 @@
+// Package implements loading of fluent-bit configuration file. Allows plugin to access values
+// defined in configuration file.
+
+package config
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"unsafe"
+
+	"github.com/fluent/fluent-bit-go/output"
+)
+
+// Holds settings for s3 clp plugin from user defined fluent-bit configuration file.
+type S3Config struct {
+	Id   string
+	Path string
+	File string
+}
+
+// Generates configuration struct containing user-defined settings.
+//
+// Parameters:
+//   - plugin: fluent-bit plugin reference
+//
+// Returns:
+//   - S3Config: Configuration based on fluent-bit.conf
+//   - err: All errors in config wrapped
+func S3New(plugin unsafe.Pointer) (*S3Config, error) {
+
+	// Slice holds config errors allowing function to return all errors at once instead of
+	// one at a time. User can fix all errors at once.
+	configErrors := []error{}
+
+	id, errID := getValueFLBConfig(plugin, "Id")
+	configErrors = append(configErrors, errID)
+
+	path, errPath := getValueFLBConfig(plugin, "Path")
+	configErrors = append(configErrors, errPath)
+
+	file, errFile := getValueFLBConfig(plugin, "File")
+	configErrors = append(configErrors, errFile)
+
+	config := &S3Config{
+		Id:   id,
+		Path: path,
+		File: file,
+	}
+
+	// Wrap all errors into one error before returning. Automically excludes nil errors.
+	err := errors.Join(configErrors...)
+	return config, err
+}
+
+// Retrieves individuals values from fluent-bit.conf.
+//
+// Parameters:
+//   - plugin: fluent-bit plugin reference
+//   - configKey: Key from fluent-bit.conf
+//
+// Returns:
+//   - configValue
+//   - err: Error if config value is blank
+func getValueFLBConfig(plugin unsafe.Pointer, configKey string) (string, error) {
+	configValue := output.FLBPluginConfigKey(plugin, configKey)
+
+	if configValue == "" {
+		err := fmt.Errorf("%s is not defined in fluent-bit configuration", configKey)
+		return configValue, err
+	}
+	log.Printf("fluent-bit config key %s set to value %s", configKey, configValue)
+	return configValue, nil
+}

go.mod

@@ -1,3 +1,7 @@
 module github.com/y-scope/fluent-bit-clp
 
 go 1.22.3
+
+require github.com/fluent/fluent-bit-go v0.0.0-20230731091245-a7a013e2473c
+
+require github.com/ugorji/go/codec v1.1.7 // indirect

go.sum

@@ -0,0 +1,5 @@
+github.com/fluent/fluent-bit-go v0.0.0-20230731091245-a7a013e2473c h1:yKN46XJHYC/gvgH2UsisJ31+n4K3S7QYZSfU2uAWjuI=
+github.com/fluent/fluent-bit-go v0.0.0-20230731091245-a7a013e2473c/go.mod h1:L92h+dgwElEyUuShEwjbiHjseW410WIcNz+Bjutc8YQ=
+github.com/ugorji/go v1.1.7/go.mod h1:kZn38zHttfInRq0xu/PH0az30d+z6vm202qpg1oXVMw=
+github.com/ugorji/go/codec v1.1.7 h1:2SvQaVZ1ouYrrKKwoSk2pzd4A9evlKJb9oTL+OaLUSs=
+github.com/ugorji/go/codec v1.1.7/go.mod h1:Ax+UKWsSmolVDwsd+7N3ZtXu+yMGCf907BLYF3GoBXY=

internal/constant/constant.go

@@ -0,0 +1,4 @@
+// Package contains constants.
+package constant
+
+const S3PluginName = "out_clp_s3"

plugins/out_clp_s3/Dockerfile

@@ -0,0 +1,33 @@
+# Builds plugin binary in go container and then runs in fluent-bit container.
+
+# Using bullseye tag to match debian version from fluent-bit image [fluent-bit Debian version].
+# Matching debian versions prevents glibc compatibility issues.
+# [fluent-bit Debian version]: https://github.com/fluent/fluent-bit/blob/master/dockerfiles/Dockerfile
+FROM golang:1.22.3-bullseye as builder
+
+# install task
+RUN sh -c "$(curl --location https://taskfile.dev/install.sh)" -- -d -b /bin
+
+WORKDIR /root
+
+ENV GOOS=linux\
+    GOARCH=amd64
+
+COPY / /root/
+
+RUN go mod download
+
+WORKDIR /root/plugins/out_clp_s3
+
+RUN task build
+
+FROM fluent/fluent-bit:3.0.6
+
+# Copy plugin binary to fluent-bit image. 
+COPY --from=builder /root/plugins/out_clp_s3/out_clp_s3.so /fluent-bit/bin/
+COPY --from=builder /root/plugins/out_clp_s3/*.conf /fluent-bit/etc/
+
+# Port for listening interface for HTTP Server.
+EXPOSE 2020
+
+CMD ["/fluent-bit/bin/fluent-bit", "--config", "/fluent-bit/etc/fluent-bit.conf"]

plugins/out_clp_s3/README.md

@@ -1,3 +1,54 @@
 # S3 CLP output plugin
 
 Output plugin for fluent-bit that sends records in CLP IR format to AWS S3.
+
+### Getting Started
+
+You can start the plugin
+- [Using Docker](#using-docker)
+- [Using local setup](#using-local-setup)
+
+#### Using Docker
+
+First build the image
+  ```shell
+  docker build ../../ -t fluent-bit-clp -f Dockerfile
+  ```
+
+Start a container
+  ```shell
+  docker run -it -v $(pwd):/root/fluent-bit/logs:rw --rm fluent-bit-clp
+  ```
+
+ Dummy logs will be written to your current working directory.
+
+#### Using local setup
+
+Install [go][1] and [fluent-bit][2]
+
+Run task to build a binary in the plugin directory
+  ```shell
+  task build
+  ```
+Change [plugin-config.conf](plugin-config.conf) to reference the plugin binary
+  ```shell
+  [PLUGINS]
+      Path /<LOCAL_PATH>/out_clp_s3.so
+  ```
+
+Change [fluent-bit.conf](fluent-bit.conf) to specify
+- Id (output name),
+- Path (output directory)
+- File (output file name)
+
+  ```shell
+  [OUTPUT]
+      name  out_clp_s3
+      Id   <OUTPUT_NAME>
+      Path <OUTPUT_DIRECTORY>
+      File <OUTPUT_FILE_NAME>
+      match *
+  ```
+
+[1]: https://go.dev/doc/install
+[2]: https://docs.fluentbit.io/manual/installation/getting-started-with-fluent-bit

plugins/out_clp_s3/Taskfile.yml

@@ -0,0 +1,15 @@
+version: '3'
+
+tasks:
+  build:
+    cmds:
+      - go build -buildmode=c-shared -o out_clp_s3.so
+    sources:
+      - ./**/*.go
+    generates:
+      - out_clp_s3.h
+      - out_clp_s3.go
+
+  clean:
+    cmds:
+      - rm -rf *.so *.h *~

plugins/out_clp_s3/fluent-bit.conf

@@ -0,0 +1,53 @@
+#Sample fluent-bit configuration with output set to clp s3 plugin.
+
+[SERVICE]
+    # Flush
+    # =====
+    # set an interval of seconds before to flush records to a destination
+    flush        1
+
+    # Daemon
+    # ======
+    # instruct Fluent Bit to run in foreground or background mode.
+    daemon       Off
+
+    # Log_Level
+    # =========
+    # Set the verbosity level of the service, values can be:
+    #
+    # - error
+    # - warning
+    # - info
+    # - debug
+    # - trace
+    #
+    # by default 'info' is set, that means it includes 'error' and 'warning'.
+    log_level    info
+
+    # Plugins File
+    # ============
+    # specify an optional 'Plugins' configuration file to load external plugins.
+    plugins_file /fluent-bit/etc/plugin-config.conf
+    # plugins_file plugin-config.conf
+
+    # HTTP Server
+    # ===========
+    # Enable/Disable the built-in HTTP Server for metrics.
+    http_server  Off
+    http_listen  0.0.0.0
+    http_port    2020
+
+[INPUT]
+    name cpu
+    tag  cpu.local
+
+    # Read interval (sec) Default: 1
+    interval_sec 1
+
+[OUTPUT]
+    name  out_clp_s3
+    Id   dummy_metrics
+    Path /root/fluent-bit/logs
+    #Path ./
+    File dummy.txt
+    match *

plugins/out_clp_s3/flush/flush.go

@@ -0,0 +1,88 @@
+// Package implements methods to send data to output. All data provided by fluent-bit is encoded
+// with msgpack.
+
+package flush
+
+import (
+	"C"
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+	"unsafe"
+
+	"github.com/fluent/fluent-bit-go/output"
+
+	"github.com/y-scope/fluent-bit-clp/config"
+)
+
+// Flushes data to file.
+//
+// Parameters:
+//   - data: msgpack data
+//   - length: Byte length
+//   - tag: fluent-bit tag
+//   - S3Config: Configuration based on fluent-bit.conf
+//
+// Returns:
+//   - err: Error if flush fails
+func File(data unsafe.Pointer, length int, tag string, config *config.S3Config) error {
+	fullFilePath := filepath.Join(config.Path, config.File)
+
+	// If the file doesn't exist, create it, or append to the file. Will still cause error if there
+	// is no directory
+	f, err := os.OpenFile(fullFilePath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0o644)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	/* ================== This code is mostly boilerplate [fluent-bit reference] ================== */
+	// Temporary changes were made to boilerplate so that writes to file instead of stdout.
+	// TODO: Update code so converts to IR and sends to s3.
+	// [fluent-bit reference]: https://github.com/fluent/fluent-bit-go/blob/a7a013e2473cdf62d7320822658d5816b3063758/examples/out_multiinstance/out.go#L41
+	// nolint:revive
+	dec := output.NewDecoder(data, length)
+
+	// Buffered writer improves performance and simplifies error handling. Checking for error when
+	// flushing simplifies retry since nothing before error is written to file (written to buffer
+	// instead). Buffer size set to value provided by fluent-bit to prevent overflow errors.
+	w := bufio.NewWriterSize(f, length)
+
+	count := 0
+	for {
+		ret, ts, record := output.GetRecord(dec)
+		if ret != 0 {
+			break
+		}
+
+		var timestamp time.Time
+		switch t := ts.(type) {
+		case output.FLBTime:
+			timestamp = ts.(output.FLBTime).Time
+		case uint64:
+			timestamp = time.Unix(int64(t), 0)
+		default:
+			fmt.Println("time provided invalid, defaulting to now.")
+			timestamp = time.Now()
+		}
+
+		// Temporary change to boilerplate so writes to file.
+		// TODO: Update code so converts to IR and sends to s3
+		_, _ = w.WriteString(fmt.Sprintf("[%d] %s: [%s, {", count, tag, timestamp.String()))
+
+		for k, v := range record {
+			_, _ = w.WriteString(fmt.Sprintf("\"%s\": %v, ", k, v))
+		}
+
+		_, _ = w.WriteString("}\n")
+		count++
+	}
+	/* ================== End of boilerplate ================== */
+
+	// If an error occurs writing to a Writer, Writer.Flush will return the error.
+	err = w.Flush()
+	return err
+}