Amazon web services lambda在完成之前退出，不等待

我正在尝试创建一个lambda函数，该函数使用

sharp

调整图像大小，但是它在完成任务之前退出。我用了

wait

be似乎它不等待

这是我的代码：

    const fileName = decodeURIComponent(event.Records[0].s3.object.key).replace(/\+/g, ' ')
    const bucket = event.Records[0].s3.bucket.name
    const keyName = fileName.split(".").slice(0, -1).join(".")
    const imageName = keyName.split("/").slice(-1).join()
    const imageFormat = fileName.split(".").slice(-1).pop()

    console.log("Getting object from S3")
    const imageData = await s3.getObject({ Bucket: bucket, Key: fileName }).promise()
    const imagePath = `/tmp/${imageName}.${imageFormat}`

    console.log('creating image file')
    fs.createWriteStream(imagePath)

    console.log("Writing buffer on the file")
    fs.writeFile(imagePath, imageData.Body, async () => {
        const myMap = new Map();
        await Promise.all(
            sizes.map(async (size) => {
                const newImageName = `${imageName}_${size.name}.${imageFormat}`
                const output = `/tmp/${newImageName}`

                console.log('Going to resize image')
                await sharp(imagePath).resize({ width: size.width, height: size.height }).toFile(output)
                console.log("Resized image")
                myMap.set(size.name, { newImagePath: output, newImageName: newImageName })
            })
        )

        console.log("map", myMap)
        await Promise.all(
            Array.from(myMap).map(async ([key, value]) => {
                const params = {
                    Bucket: bucket,
                    Key: `images/${key}/${value.newImageName}`,
                    Body: value.newImagePath,
                    ContentType: `image/${imageFormat}`
                }
        
                console.log("Uploading to S3")
                await s3.putObject(params).promise()
            })
        )
    })

这是AWS cloudwatch日志：

START RequestId: 9199e286-c850-40ef-bc6e-e6541741bda7 Version: $LATEST
2021-04-26T05:52:45.150Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    Env variable is detected:  true
2021-04-26T05:52:45.150Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    image format is:  jpg
2021-04-26T05:52:45.150Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    Getting object from S3
2021-04-26T05:52:45.328Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    creating image file
2021-04-26T05:52:45.328Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    Writing buffer on the file
2021-04-26T05:52:45.348Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    Going to resize image
2021-04-26T05:52:45.370Z    9199e286-c850-40ef-bc6e-e6541741bda7    INFO    Going to resize image
END RequestId: 9199e286-c850-40ef-bc6e-e6541741bda7
REPORT RequestId: 9199e286-c850-40ef-bc6e-e6541741bda7  Duration: 549.10 ms Billed Duration: 550 ms Memory Size: 512 MB Max Memory Used: 134 MB Init Duration: 760.73 ms    

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有什么想法吗？

fs.writeFile会返回一个您忽略的承诺。您需要返回该承诺，以便Lambda知道等待，对吗？当您提供回调时，它不会返回承诺。这是一个问题，因为它调用的是异步回调，而不是等待对吗？