Managing jobs - AWS IoT Core
Code signing for jobsJob documentPresigned URLsPresigned URL for file uploadPresigned URL using Amazon S3 versioning

Managing jobs

Use jobs to notify devices of a software or firmware update. You can use the AWS IoT console, the Job management and control API operations, the AWS Command Line Interface, or the AWS SDKs to create and manage jobs.

Code signing for jobs

When sending code to devices, for devices to detect whether the code has been modified in transit, we recommend that you sign the code file by using the AWS CLI. For instructions, see Create and manage jobs by using the AWS CLI.

For more information, see What Is Code Signing for AWS IoT?.

Job document

Before you create a job, you must create a job document. If you're using code signing for AWS IoT, you must upload your job document to a versioned Amazon S3 bucket. For more information about creating an Amazon S3 bucket and uploading files to it, see Getting Started with Amazon Simple Storage Service in the Amazon S3 Getting Started Guide.

Tip

For job document examples, see the jobs-agent.js example in the AWS IoT SDK for JavaScript.

Presigned URLs

Your job document can contain a presigned Amazon S3 URL that points to your code file (or other file). Presigned Amazon S3 URLs are valid only for a limited amount of time and are generated when a device requests a job document. Because the presigned URL isn't created when you're creating the job document, use a placeholder URL in your job document instead. A placeholder URL looks like the following:

${aws:iot:s3-presigned-url-v2:https://s3.region.amazonaws.com/<bucket>/<code file>}

where:

  • bucket is the Amazon S3 bucket that contains the code file.

  • code file is the Amazon S3 key of the code file.

When a device requests the job document, AWS IoT generates the presigned URL and replaces the placeholder URL with the presigned URL. Your job document is then sent to the device.

IAM role to grant permission to download files from S3

When you create a job that uses presigned Amazon S3 URLs, you must provide an IAM role. The role must grant permission to download files from the Amazon S3 bucket where the data or updates are stored. The role must also grant permission for AWS IoT to assume the role.

You can specify an optional timeout for the presigned URL. For more information, see CreateJob.

Grant AWS IoT Jobs permission to assume your role

  1. Go to the Roles hub of the IAM console and choose your role.

  2. On the Trust Relationships tab, choose Edit Trust Relationship and replace the policy document with the following JSON. Choose Update Trust Policy.

    {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "",
      "Effect": "Allow",
      "Principal": {
        "Service": [
          "iot.amazonaws.com"
        ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

  3. To protect against the confused deputy problem, add the global condition context keys aws:SourceArn and aws:SourceAccount to the policy.

    Important

    Your aws:SourceArn must comply with the format: arn:aws:iot:region:account-id:*. Make sure that region matches your AWS IoT Region and account-id matches your customer account ID. For more information, see Cross-service confused deputy prevention. 

    {
  "Effect": "Allow",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": 
          "iot.amazonaws.com"        
       },
      "Action": "sts:AssumeRole",
      "Condition": {
         "StringEquals": {
            "aws:SourceAccount": "123456789012"
         },
         "ArnLike": {
              "aws:SourceArn": "arn:aws:iot:*:123456789012:job/*"
         }
       }
     }
   ]
}

  4. If your job uses a job document that's an Amazon S3 object, choose Permissions and use the following JSON. This adds a policy that grants permission to download files from your Amazon S3 bucket:

    {
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::your_S3_bucket/*"
        }
    ]
}

Presigned URL for file upload

If your devices need to upload files to an Amazon S3 bucket during a job deployment, then you can include the following presigned URL placeholder in your job document: 

${aws:iot:s3-presigned-url-v2-upload:https://s3.region.amazonaws.com/<bucket>/<key>}

You can use a max of two of each of ${thingName}, ${jobId}, and ${executionNumber} as reserved keywords within the key attribute in the file upload placeholder URL located in your job document. The local placeholder representing those reserved keywords in the key attribute will be parsed and replaced when the job execution is created. Using a local placeholder with reserved keywords specific to each device ensures each uploaded file from a device is specific to that device and not overwritten by a similar uploaded file from another device targeted by the same job deployment. For information on troubleshooting local placeholders within a presigned URL placeholder for uploading files during a job deployment, see General Troubleshooting Error Messages.

Note

The Amazon S3 bucket name can't contain the local placeholder representing the reserved keywords for the uploaded file. The local placeholder must be located in the key attribute.

This presigned URL placeholder will be converted to an Amazon S3 presigned upload URL in your job document when a device receives it. Your devices will use this to upload files to a destination Amazon S3 bucket.

Note

When the Amazon S3 bucket and key are not provided in the above placeholder URL, AWS IoT Jobs will automatically generate a key for each device using a max of two of each of ${thingName}, ${jobId}, and ${executionNumber}.

Presigned URL using Amazon S3 versioning

Safeguarding the integrity of a file stored in an Amazon S3 bucket is critical for ensuring secure job deployments using that file to your device fleet. With the use of Amazon S3 versioning, you can add a version identifier for each variant of the file stored in your Amazon S3 bucket for tracking each verison of the file. This provides insight into what version of the file is deployed to your device fleet using AWS IoT Jobs. For more information on Amazon S3 buckets using versioning, see Using versioning in Amazon S3 buckets.

If the file is stored in Amazon S3 and the job document contains a presigned URL placeholder, AWS IoT Jobs will generate a presigned URL in the job document using the Amazon S3 bucket, bucket key, and version of the file stored in the Amazon S3 bucket. This presigned URL generated in the job document will replace the presigned URL placeholder originally in the job document. If you update the file stored in your Amazon S3 bucket, a new version of the file and subsequent versionId will be created to signal the updates made and provide the ability to target that specific file in future job deployments.

Refer to the following examples for a before and during look of the Amazon S3 presigned URLs in your job document using the versionId:

Amazon S3 Presigned URL placeholder (Before Job Deployment)

//Virtual-hosted style URL
${aws:iot:s3-presigned-url-v2:https://bucket-name.s3.region-code.amazonaws.com/key-name%3FversionId%3Dversion-id}

//Path-style URL
${aws:iot:s3-presigned-url-v2:https://s3.region-code.amazonaws.com/bucket-name/key-name%3FversionId%3Dversion-id}

Amazon S3 Presigned URL (During Job Deployment)

//Virtual-hosted style URL
${aws:iot:s3-presigned-url-v2:https://sample-bucket-name.s3.us-west-2.amazonaws.com/sample-code-file.png%3FversionId%3Dversion1}

//Path-style
${aws:iot:s3-presigned-url-v2:https://s3.us-west-2.amazonaws.com/sample-bucket-name/sample-code-file.png%3FversionId%3Dversion1}

For more information on Amazon S3 virtual-hosted and path-style object URLs, see Virtual-hosted-style requests and Path-style requests.

Note

If you want to append versionId to a Amazon S3 presigned URL, it must conform to URL encoding supporting AWS SDK for Java 2.x. For more information, see Changes in parsing Amazon S3 URIs from version 1 to version 2.

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