CODEWITHSUNDEEP
dockergoapache-kafkadockerfileconfluent-platform
Nik
Nik

Reputation: 51

Docker build fails due to kafka undefined error

When I am trying to build our go application we are getting the below error.

=> ERROR [builder 7/7] RUN CGO_ENABLED=0 GOOS=linux go build -o myapp
 > [builder 7/7] RUN CGO_ENABLED=0 GOOS=linux go build -o myapp:
#14 6.962 # main
#14 6.962 ./kafkaproducer.go:12:12: undefined: kafka.NewProducer
#14 6.962 ./kafkaproducer.go:12:31: undefined: kafka.ConfigMap
#14 6.962 ./kafkaproducer.go:23:10: undefined: kafka.Message
#14 6.962 ./kafkaproducer.go:39:13: undefined: kafka.Message

My Docker file is

FROM golang:1.16-alpine AS builder
RUN mkdir /app
ADD . /app
WORKDIR /app
RUN go mod tidy
RUN CGO_ENABLED=0 GOOS=linux go build -o myapp
FROM busybox AS prod
COPY --from=builder /app .
CMD ["./myapp"]

In my kafkaProducer go file I am importing this

import (
    "fmt"
    "log"

    "github.com/confluentinc/confluent-kafka-go/kafka"
)

My application is built successfully when I build it locally but through docker build is getting failed as it is unable to download kafka dependency and undefined error is thrown. Please help me fix this issue

Upvotes: 5

Views: 2120

Answers (1)

The Fool
The Fool

Reputation: 20537

So somehow this seems to depend on cgo when building. I managed to work around this by compiling with cgo, but linking the dependencies statically.

FROM golang AS builder

WORKDIR /app
COPY . .
RUN go mod download && \
    go build -o myapp -ldflags '-linkmode external -w -extldflags "-static"'


# works also with alpine
FROM busybox 

COPY --from=builder /app/myapp myapp
CMD ["./myapp"]

I have used the code below, from their repo, to test. Which gave me initially the kind of error you have shown.

package main

import (
    "fmt"

    "github.com/confluentinc/confluent-kafka-go/kafka"
)

func main() {

    p, err := kafka.NewProducer(&kafka.ConfigMap{"bootstrap.servers": "localhost"})
    if err != nil {
        panic(err)
    }

    defer p.Close()

    // Delivery report handler for produced messages
    go func() {
        for e := range p.Events() {
            switch ev := e.(type) {
            case *kafka.Message:
                if ev.TopicPartition.Error != nil {
                    fmt.Printf("Delivery failed: %v\n", ev.TopicPartition)
                } else {
                    fmt.Printf("Delivered message to %v\n", ev.TopicPartition)
                }
            }
        }
    }()

    // Produce messages to topic (asynchronously)
    topic := "myTopic"
    for _, word := range []string{"Welcome", "to", "the", "Confluent", "Kafka", "Golang", "client"} {
        p.Produce(&kafka.Message{
            TopicPartition: kafka.TopicPartition{Topic: &topic, Partition: kafka.PartitionAny},
            Value:          []byte(word),
        }, nil)
    }

    // Wait for message deliveries before shutting down
    p.Flush(15 * 1000)
}

Upvotes: 2

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