AWS lambda no such file exists error in serverless

Question

Hey I was following this blog post - https://www.serverless.com/blog/publish-aws-lambda-layers-serverless-framework which creates gif from video files using ffmpeg.

My file structure -

gifmaker

• layer
  • ffmpeg library
• handler.js
• serverless.yml

My handler.js code -

const { spawnSync } = require("child_process");
const { readFileSync, writeFileSync, unlinkSync } = require("fs");
const AWS = require("aws-sdk");

const s3 = new AWS.S3();

module.exports.mkgif = async (event, context) => {
  if (!event.Records) {
    console.log("not an s3 invocation!");
    return;
  }
  for (const record of event.Records) {
    if (!record.s3) {
      console.log("not an s3 invocation!");
      continue;
    }
    if (record.s3.object.key.endsWith(".gif")) {
      console.log("already a gif");
      continue;
    }
    // get the file
    const s3Object = await s3
      .getObject({
        Bucket: record.s3.bucket.name,
        Key: record.s3.object.key
      })
      .promise();
    // write file to disk
    writeFileSync(`/tmp/${record.s3.object.key}`, s3Object.Body);
    // convert to gif!
    spawnSync(
      "/opt/ffmpeg/ffmpeg",
      [
        "-i",
        `/tmp/${record.s3.object.key}`,
        "-f",
        "gif",
        `/tmp/${record.s3.object.key}.gif`
      ],
      { stdio: "inherit" }
    );
    // read gif from disk
    const gifFile = readFileSync(`/tmp/${record.s3.object.key}.gif`);
    // delete the temp files
    unlinkSync(`/tmp/${record.s3.object.key}.gif`);
    unlinkSync(`/tmp/${record.s3.object.key}`);
    // upload gif to s3
    await s3
      .putObject({
        Bucket: record.s3.bucket.name,
        Key: `${record.s3.object.key}.gif`,
        Body: gifFile
      })
      .promise();
  }
};

my serverless.yml -

service: gifmaker
frameworkVersion: "2"

provider:
  name: aws
  runtime: nodejs12.x
  region: ap-south-1
  iamRoleStatements:
    - Effect: Allow
      Action:
        - s3:PutObject
        - s3:GetObject
      Resource: "arn:aws:s3:::${self:custom.bucket}/*"

functions:
  mkgif:
    handler: handler.mkgif
    events:
      - s3: ${self:custom.bucket}
    layers:
      - {Ref: FfmpegLambdaLayer}

layers:
  ffmpeg:
    path: layer

custom:
  bucket: ${env:BUCKET, 'newsgator-company4'}

Getting this error -

2020-10-07T22:32:14.695Z    13d283af-13dd-40e4-ae52-e1fc0d41f547    ERROR   Invoke Error    
{
    "errorType": "Error",
    "errorMessage": "ENOENT: no such file or directory, open '/tmp/data_store/0009.mp4'",
    "code": "ENOENT",
    "errno": -2,
    "syscall": "open",
    "path": "/tmp/data_store/0009.mp4",
    "stack": [
        "Error: ENOENT: no such file or directory, open '/tmp/data_store/0009.mp4'",
        "    at Object.openSync (fs.js:462:3)",
        "    at writeFileSync (fs.js:1362:35)",
        "    at Runtime.module.exports.mkgif [as handler] (/var/task/handler.js:29:5)",
        "    at runMicrotasks (<anonymous>)",
        "    at processTicksAndRejections (internal/process/task_queues.js:97:5)"
    ]
}

I have been stuck on this for hours now, cant figure out the issue. Also the lambda function has administrator role.

Answer 1

As I see the problem is that you are giving a path that doesn't exist

writeFileSync(`/tmp/${record.s3.object.key}`, s3Object.Body);

this becomes -> /tmp/data_store/0009.mp4

Your solution would work if your record.s3.object.key is just 0009.mp4 and your route would be /tmp/0009.mp4 -> this would work because writeFileSync can create a file if the file doesn't exist but in your case, it's not possible because you don't have directory data_store and because that this is not working.