由于 kafka 未定义错误，Docker 构建失败

Question

当我尝试构建我们的 go 应用程序时，我们收到以下错误。

=> 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

我的 Docker 文件是

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"]

在我的 kafkaProducer go 文件中，我正在导入这个

import (
    "fmt"
    "log"

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

我的应用程序在本地构建时构建成功，但通过 docker build 失败，因为它无法下载 kafka 依赖项并抛出未定义的错误。 请帮我解决这个问题

Answer 1

所以在构建时这似乎取决于 cgo。我设法通过使用 cgo 编译解决了这个问题，但静态链接了依赖项。

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"]

我使用下面的代码from their repo 进行测试。这最初给了我你所显示的那种错误。

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)
}