Export files to Amazon S3

🤖/s3/store exports encoding results to Amazon S3.

If you are new to Amazon S3, see our tutorial on using your own S3 bucket.

The URL to the result file in your S3 bucket will be returned in the Assembly Status JSON.

Avoid permission errors. By default, acl is set to "public". AWS S3 has a bucket setting called "Block new public ACLs and uploading public objects". Set this to False in your bucket if you intend to leave acl as "public". Otherwise, you’ll receive permission errors in your Assemblies despite your S3 credentials being configured correctly.

Use DNS-compliant bucket names. Your bucket name must be DNS-compliant and must not contain uppercase letters. Any non-alphanumeric characters in the file names will be replaced with an underscore, and spaces will be replaced with dashes. If your existing S3 bucket contains uppercase letters or is otherwise not DNS-compliant, rewrite the result URLs using the Robot’s url_prefix parameter.

Limit access

You will also need to add permissions to your bucket so that Transloadit can access it properly. Here is an example IAM policy that you can use. Following the principle of least privilege, it contains the minimum required permissions to export a file to your S3 bucket using Transloadit. You may require more permissions (especially viewing permissions) depending on your application.

Please change {BUCKET_NAME} in the values for Sid and Resource accordingly. Also, this policy will grant the minimum required permissions to all your users. We advise you to create a separate Amazon IAM user, and use its User ARN (can be found in the "Summary" tab of a user here) for the Principal value. More information about this can be found here.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowTransloaditToStoreFilesIn{BUCKET_NAME}Bucket",
      "Effect": "Allow",
      "Action": ["s3:GetBucketLocation", "s3:ListBucket", "s3:PutObject", "s3:PutObjectAcl"],
      "Resource": ["arn:aws:s3:::{BUCKET_NAME}", "arn:aws:s3:::{BUCKET_NAME}/*"]
    }
  ]
}

The Sid value is just an identifier for you to recognize the rule later. You can name it anything you like.

The policy needs to be separated into two parts, because the ListBucket action requires permissions on the bucket while the other actions require permissions on the objects in the bucket. When targeting the objects there's a trailing slash and an asterisk in the Resource parameter, whereas when the policy targets the bucket, the slash and the asterisk are omitted.

Please note that if you give the Robot's acl parameter a value of "bucket-default", then you do not need the "s3:PutObjectAcl" permission in your bucket policy.

In order to build proper result URLs we need to know the region in which your S3 bucket resides. For this we require the GetBucketLocation permission. Figuring out your bucket's region this way will also slow down your Assemblies. To make this much faster and to also not require the GetBucketLocation permission, we have added the bucket_region parameter to the /s3/store and /s3/import Robots. We recommend using them at all times.

Please keep in mind that if you use bucket encryption you may also need to add "sts:*" and "kms:*" to the bucket policy. Please read here and here in case you run into trouble with our example bucket policy.

Parameters

use

String / Array of Strings / Objectrequired
Specifies which Step(s) to use as input.
- You can pick any names for Steps except ":original" (reserved for user uploads handled by Transloadit)
- You can provide several Steps as input with arrays:
```
"use": [
  ":original",
  "encoded",
  "resized"
]
```
💡 That’s likely all you need to know about use, but you can view advanced use cases:
› Advanced use cases
- Step bundling. Some Robots can gather several Step results for a single invocation. For example, 🤖/file/compress would normally create one archive for each file passed to it. If you'd set bundle_steps to true, however, it will create one archive containing all the result files from all Steps you give it. To enable bundling, provide an object like the one below to the use parameter:
```
"use": {
  "steps": [
    ":original",
    "encoded",
    "resized"
  ],
  "bundle_steps": true
}
```
  This is also a crucial parameter for 🤖/video/adaptive, otherwise you'll generate 1 playlist for each viewing quality.
  Keep in mind that all input Steps must be present in your Template. If one of them is missing (for instance it is rejected by a filter), no result is generated because the Robot waits indefinitely for all input Steps to be finished.
  
  Here’s a demo that showcases Step bundling.
- Group by original. Sticking with 🤖/file/compress example, you can set group_by_original to true, in order to create a separate archive for each of your uploaded or imported files, instead of creating one archive containing all originals (or one per resulting file). This is important for for 🤖/media/playlist where you'd typically set:
```
"use": {
  "steps": [
    "segmented"
  ],
  "bundle_steps": true,
  "group_by_original": true
}
```
- Fields. You can be more discriminatory by only using files that match a field name by setting the fields property. When this array is specified, the corresponding Step will only be executed for files submitted through one of the given field names, which correspond with the strings in the name attribute of the HTML file input field tag for instance. When using a back-end SDK, it corresponds with myFieldName1 in e.g.: $transloadit->addFile('myFieldName1', './chameleon.jpg').
  
  This parameter is set to true by default, meaning all fields are accepted.
  
  Example:
```
"use": {
  "steps": [ ":original" ],
  "fields": [ "myFieldName1" ]
}
```
- Use as. Sometimes Robots take several inputs. For instance, 🤖/video/merge can create a slideshow from audio and images. You can map different Steps to the appropriate inputs.
  
  Example:
```
"use": {
  "steps": [
    { "name": "audio_encoded", "as": "audio" },
    { "name": "images_resized", "as": "image" }
  ]
}
```
  Sometimes the ordering is important, for instance, with our concat Robots. In these cases, you can add an index that starts at 1. You can also optionally filter by the multipart field name. Like in this example, where all files are coming from the same source (end-user uploads), but with different <input> names:
  
  Example:
```
"use": {
  "steps": [
    { "name": ":original", "fields": "myFirstVideo", "as": "video_1" },
    { "name": ":original", "fields": "mySecondVideo", "as": "video_2" },
    { "name": ":original", "fields": "myThirdVideo", "as": "video_3" }
  ]
}
```
  For times when it is not apparent where we should put the file, you can use Assembly Variables to be specific. For instance, you may want to pass a text file to 🤖/image/resize to burn the text in an image, but you are burning multiple texts, so where do we put the text file? We specify it via ${use.text_1}, to indicate the first text file that was passed.
  
  Example:
```
"watermarked": {
  "robot": "/image/resize",
  "use"  : {
    "steps": [
      { "name": "resized", "as": "base" },
      { "name": "transcribed", "as": "text" },
    ],
  },
  "text": [
    {
      "text"  : "Hi there",
      "valign": "top",
      "align" : "left",
    },
    {
      "text"    : "From the 'transcribed' Step: ${use.text_1}",
      "valign"  : "bottom",
      "align"   : "right",
      "x_offset": 16,
      "y_offset": -10,
    }
  ]
}
```
credentials

Stringrequired

Please create your associated Template Credentials in your Transloadit account and use the name of your Template Credentials as this parameter's value. They will contain the values for your S3 bucket, Key, Secret and Bucket region.

While we recommend to use Template Credentials at all times, some use cases demand dynamic credentials for which using Template Credentials is too unwieldy because of their static nature. If you have this requirement, feel free to use the following parameters instead: "bucket", "bucket_region" (for example: "us-east-1" or "eu-west-2"), "key", "secret".
path

String ⋅ default: "${unique_prefix}/${file.url_name}"

The path at which the file is to be stored. This may include any available Assembly variables. The path must not be a directory.
url_prefix

String ⋅ default: "http://{bucket}.s3.amazonaws.com/"

The URL prefix used for the returned URL, such as "http://my.cdn.com/some/path/".
acl

String ⋅ default: "public-read"

The permissions used for this file. This can be "public-read", "public", "private" or "bucket-default".

Please keep in mind that the default value "public-read" can lead to permission errors due to the "Block all public access" checkbox that is checked by default when creating a new Amazon S3 Bucket in the AWS console.
check_integrity

Boolean ⋅ default: false

Calculate and submit the file's checksum in order for S3 to verify its integrity after uploading, which can help with occasional file corruption issues.

Enabling this option adds to the overall execution time, as integrity checking can be CPU intensive, especially for larger files.
headers

Object ⋅ default: { "Content-Type": "${file.mime}" }

An object containing a list of headers to be set for this file on S3, such as { FileURL: "${file.url_name}" }. This can also include any available Assembly Variables. You can find a list of available headers here.

Object Metadata can be specified using x-amz-meta-* headers. Note that these headers do not support non-ASCII metadata values.
host

String ⋅ default: "s3.amazonaws.com"

The host of the storage service used. This only needs to be set when the storage service used is not Amazon S3, but has a compatible API (such as hosteurope.de).
no_vhost

Boolean ⋅ default: false

Set to true if you use a custom host and run into access denied errors.
sign_urls_for

Integer

This parameter provides signed URLs in the result JSON (in the signed_url and signed_ssl_url properties). The number that you set this parameter to is the URL expiry time in seconds. If this parameter is not used, no URL signing is done.

Note: The URLs in the result JSON already point to the file on your target storage platform, so you can just save that URL in your database.

Export files to Amazon S3

Limit access

Parameters

`use`

`credentials`

`path`

`url_prefix`

`acl`

`check_integrity`

`headers`

`host`

`no_vhost`

`sign_urls_for`

Demos

Related blog posts