presign_post

README

Custom PresignClient for presigned POST using the AWS s3 Go SDK (v2)

Why?

The official SDK has not had a way to create presigned POST urls, despite having an open issue and associated PR for over 2 years. This module adds support for creating these presigned POST urls in the cleanest way possible

Usage

package main

import (
	"context"
	"fmt"
	"time"

	presign_post "github.com/PretendoNetwork/aws-sdk-presigned-post-go"
	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/credentials"
)

func main() {
	s3Endpoint := "https://s3.example.com"
	s3Region := "us-east-1"
	s3AccessKey := "key_id"
	s3AccessSecret := "key_secret"
	bucket := "bucket"
	key := "file.bin"

	staticCredentials := credentials.NewStaticCredentialsProvider(s3AccessKey, s3AccessSecret, "")

	endpointResolver := aws.EndpointResolverWithOptionsFunc(func(service, region string, options ...interface{}) (aws.Endpoint, error) {
		return aws.Endpoint{
			URL: s3Endpoint,
		}, nil
	})

	cfg, err := config.LoadDefaultConfig(
		context.TODO(),
		config.WithRegion(s3Region),
		config.WithCredentialsProvider(staticCredentials),
		config.WithEndpointResolverWithOptions(endpointResolver),
	)

	if err != nil {
		panic(err)
	}

	presignPostClient := presign_post.NewPresignClient(cfg)

	input := &presign_post.PostObjectInput{
		Bucket:    bucket,
		Key:       key,
		ExpiresIn: time.Minute * 15,
	}

	res, _ := presignPostClient.PresignPostObject(input)

	fmt.Printf("%+v\n", res)
}

Disclaimers

1. This has only been tested on DigitalOcean Spaces, though it should work on any s3-compatible server
2. I was not able to find a way to get pre-formatted endpoints from the config alone, so a small regex is used to find and replace inside the endpoint string to add the bucket

Documentation

Index

• type PostObjectInput
• type PresignClient
  • func NewPresignClient(cfg aws.Config) *PresignClient
  • func (presignClient *PresignClient) PresignPostObject(input *PostObjectInput) (*PresignedPostObject, error)
• type PresignedPostObject

Types

type PostObjectInput

type PostObjectInput struct {
	// Key name
	Key string

	// The name of the bucket to presign the post to
	Bucket string

	// Expiration -  The number of seconds the presigned post is valid for.
	ExpiresIn time.Duration

	// A list of conditions to include in the policy. Each element can be either a list or a structure.
	// For example:
	// [
	//      {"acl": "public-read"}, ["content-length-range", 2, 5], ["starts-with", "$success_action_redirect", ""]
	// ]
	Conditions []interface{}
}

type PresignClient

type PresignClient struct {
	// contains filtered or unexported fields
}

func NewPresignClient

func NewPresignClient(cfg aws.Config) *PresignClient

func (*PresignClient) PresignPostObject

func (presignClient *PresignClient) PresignPostObject(input *PostObjectInput) (*PresignedPostObject, error)

type PresignedPostObject

type PresignedPostObject struct {
	URL           string `json:"url"`
	Key           string `json:"key"`
	Policy        string `json:"policy"`
	Credential    string `json:"credential"`
	SecurityToken string `json:"securityToken,omitempty"`
	Signature     string `json:"signature"`
	Date          string `json:"date"`
}