SDKs

The AWS SDKs work with MaxIOFS once they have the endpoint and path-style addressing. Credentials come from an access key created in the console.

Python (boto3)Go (SDK v2)JavaScript (SDK v3)Java (SDK v2).NET

import boto3
from botocore.config import Config

s3 = boto3.client(
    "s3",
    endpoint_url="https://s3.example.com",
    aws_access_key_id="AKIA...",
    aws_secret_access_key="...",
    region_name="us-east-1",
    config=Config(s3={"addressing_style": "path"}),
)

s3.create_bucket(Bucket="my-bucket")
s3.upload_file("report.pdf", "my-bucket", "docs/report.pdf")

for obj in s3.list_objects_v2(Bucket="my-bucket", Prefix="docs/").get("Contents", []):
    print(obj["Key"], obj["Size"])

s3.download_file("my-bucket", "docs/report.pdf", "copy.pdf")

url = s3.generate_presigned_url(
    "get_object", Params={"Bucket": "my-bucket", "Key": "docs/report.pdf"}, ExpiresIn=3600
)

upload_file and download_file switch to multipart transfers on their own for large files.

package main

import (
    "context"
    "fmt"
    "os"

    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/config"
    "github.com/aws/aws-sdk-go-v2/credentials"
    "github.com/aws/aws-sdk-go-v2/service/s3"
)

func main() {
    ctx := context.Background()
    cfg, err := config.LoadDefaultConfig(ctx,
        config.WithRegion("us-east-1"),
        config.WithCredentialsProvider(
            credentials.NewStaticCredentialsProvider("AKIA...", "...", "")),
    )
    if err != nil {
        panic(err)
    }
    client := s3.NewFromConfig(cfg, func(o *s3.Options) {
        o.BaseEndpoint = aws.String("https://s3.example.com")
        o.UsePathStyle = true
    })

    f, _ := os.Open("report.pdf")
    defer f.Close()
    _, err = client.PutObject(ctx, &s3.PutObjectInput{
        Bucket: aws.String("my-bucket"),
        Key:    aws.String("docs/report.pdf"),
        Body:   f,
    })
    if err != nil {
        panic(err)
    }

    out, _ := client.ListObjectsV2(ctx, &s3.ListObjectsV2Input{Bucket: aws.String("my-bucket")})
    for _, o := range out.Contents {
        fmt.Println(*o.Key, *o.Size)
    }
}

import { S3Client, PutObjectCommand, ListObjectsV2Command, GetObjectCommand } from "@aws-sdk/client-s3";
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";
import { readFile } from "node:fs/promises";

const s3 = new S3Client({
  endpoint: "https://s3.example.com",
  region: "us-east-1",
  forcePathStyle: true,
  credentials: { accessKeyId: "AKIA...", secretAccessKey: "..." },
});

await s3.send(new PutObjectCommand({
  Bucket: "my-bucket",
  Key: "docs/report.pdf",
  Body: await readFile("report.pdf"),
  ContentType: "application/pdf",
}));

const { Contents = [] } = await s3.send(new ListObjectsV2Command({ Bucket: "my-bucket" }));
Contents.forEach((o) => console.log(o.Key, o.Size));

const url = await getSignedUrl(s3,
  new GetObjectCommand({ Bucket: "my-bucket", Key: "docs/report.pdf" }), { expiresIn: 3600 });

import java.net.URI;
import java.nio.file.Paths;
import software.amazon.awssdk.auth.credentials.AwsBasicCredentials;
import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.PutObjectRequest;

S3Client s3 = S3Client.builder()
    .endpointOverride(URI.create("https://s3.example.com"))
    .region(Region.US_EAST_1)
    .forcePathStyle(true)
    .credentialsProvider(StaticCredentialsProvider.create(
        AwsBasicCredentials.create("AKIA...", "...")))
    .build();

s3.putObject(
    PutObjectRequest.builder().bucket("my-bucket").key("docs/report.pdf").build(),
    Paths.get("report.pdf"));

using Amazon.S3;
using Amazon.S3.Transfer;

var s3 = new AmazonS3Client("AKIA...", "...", new AmazonS3Config
{
    ServiceURL = "https://s3.example.com",
    ForcePathStyle = true,
    AuthenticationRegion = "us-east-1",
});

await new TransferUtility(s3).UploadAsync("report.pdf", "my-bucket", "docs/report.pdf");

Keep keys out of the code

Every SDK reads the standard variables and the shared profile, so the code above can drop the literal keys:

export AWS_ACCESS_KEY_ID=AKIA...
export AWS_SECRET_ACCESS_KEY=...
export AWS_ENDPOINT_URL=https://s3.example.com

For applications that should not hold permanent keys at all, issue temporary credentials.

Checksums in recent SDKs

Recent SDK versions add CRC checksums to every upload by default, sent as aws-chunked bodies with a trailer. MaxIOFS reads them; no client setting is needed.