Cache-Control set to no-cache even though not specified in Upload params

[giilby]

Checkboxes for prior research

• I've gone through Developer Guide and API reference
• I've checked AWS Forums and StackOverflow.
• I've searched for previous similar issues and didn't find any solution.

Describe the bug

I'm trying to use Upload from @aws-sdk/lib-storage to upload images to an S3 bucket. Formerly, I used PutObjectCommand and didn't have this issue. Anyway, my parameters are very simple:

const upload = new Upload({
    client: s3Client,
    params: {
      Bucket: bucket,
      Key: key,
      Body: file,
      ContentType: file.type
    },
  })

Unexpectedly, when I look at the uploaded object in S3, the Cache-Control metadata is set to no-cache, even though I didn't specify that in the params. Any idea what's going on?

Regression Issue

• Select this option if this issue appears to be a regression.

SDK version number

@aws-sdk/client-s3 v3.802.0, @aws-sdk/lib-storage v3.802.0

Which JavaScript Runtime is this issue in?

Browser

Details of the browser/Node.js/ReactNative version

Chrome: 135.0.7049.116

Reproduction Steps

const s3Client = new S3Client({
  region: 'us-east-1',
  credentials: [your credentials here]
})

// get a reference to a JPEG or PNG File object

const upload = new Upload({
  client: s3Client,
  params: {
    Bucket: 'some-bucket-name',
    Key: 'some-key-path',
    Body: file,
    ContentType: file.type
  },
})

await upload.done()

Observed Behavior

The Cache-Control metadata item is inexplicably set:

Expected Behavior

The Cache-Control metadata is not present on the object.

Possible Solution

Currently, our workaround is to include CacheControl: 'public' in our Upload params.

Additional Information/Context

No response

[zshzbh]

Hey giilby,

It seems that this cache-control is System defined. So that the system added the cache-control even though you didn't pass the value in parameter.

The Options's params in Upload comes from PutObjectCommandInput - ref

[zshzbh]

To check if there's anything in aws js sdk -

I used the code below to upload a file and check the uploaded file's metadata

import { S3Client, HeadObjectCommand } from "@aws-sdk/client-s3";
import { Upload } from "@aws-sdk/lib-storage";
import fs from "fs";

const testFileName = "test-file.txt";
fs.writeFileSync(testFileName, "This is a test file for S3 upload");

const s3Client = new S3Client({ region: "us-east-1" });
const bucket = "new-bucket-maggie-ma";

async function uploadAndCheckHeaders() {
  try {
    console.log("Uploading file...");
    const upload = new Upload({
      client: s3Client,
      params: {
        Bucket: bucket,
        Key: testFileName,
        Body: fs.readFileSync(testFileName),
        ContentType: "text/plain",
      },
    });
    
    await upload.done();
    console.log("Upload complete");
    
    console.log("Checking object metadata...");
    const headCommand = new HeadObjectCommand({
      Bucket: bucket,
      Key: testFileName
    });
    
    const headResponse = await s3Client.send(headCommand);
    console.log("Object metadata:");
    console.log(JSON.stringify(headResponse, null, 2));
    
    console.log(`Cache-Control: ${headResponse.CacheControl || 'not set'}`);
    
  } catch (error) {
    console.error("Error:", error);
  }
}

uploadAndCheckHeaders();

And the result is

node test-cache-control.mjs


Uploading file...


Upload complete


Checking object metadata...


Object metadata:


{
  "$metadata": {
    "httpStatusCode": 200,
    "requestId": "xxxxxxx",
    "extendedRequestId": "xxxxxxxxx/xXaRUxsXfPh3uCaVYGIjsaO0=",
    "attempts": 1,
    "totalRetryDelay": 0
  },
  "AcceptRanges": "bytes",
  "LastModified": "2025-05-06T21:29:44.000Z",
  "ContentLength": 33,
  "ETag": "\"xxxxx\"",
  "ContentType": "text/plain",
  "ServerSideEncryption": "AES256",
  "Metadata": {}
}
Cache-Control: not set

So it seems that Cache-Control is actually not being set by default in the S3 object metadata when using aws js sdk to upload.

When you upload an object to S3 using the AWS SDK without explicitly setting a Cache-Control header, S3 does not automatically set one on the object itself.

However, when you're seeing "Cache-Control: no-cache" in your application, it's likely coming from one of these sources:

• S3 Default Behavior for Presigned URLs: When accessing objects via presigned URLs or through the S3 website endpoint, S3 might add default headers that aren't stored with the object metadata.

• CloudFront Distribution: If you're accessing the objects through CloudFront, it might be adding its own caching headers.

• Browser Behavior: Some browsers might display a "no-cache" header when they don't receive explicit caching instructions.

I'd like to suggest to check the sources listed above. And I'd like to suggest to manually add Cache-Control if that bothers. you can view all Cache-Control directives here - https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Cache-Control