docs/backend/s3: add primary key requirement to dynamodb table
This is not trivial and only documented in the terraform s3 backend type
documentation AFAIK:
@@ -20,7 +20,7 @@ used.
## Prerequisites
* AWS S3 bucket to be used should already be created.
-* DynamoDB table to be used for state locking should already be created.
+* DynamoDB table to be used for state locking should already be created. The table must have a primary key named LockID.
* Correct IAM permissions for the S3 bucket and DynamoDB Table. At minimum the following are the
permissions required:
* [S3 bucket permissions](https://www.terraform.io/docs/backends/types/s3.html#s3-bucket-permissions).
@@ -45,13 +45,13 @@ backend "s3" {
## Attribute reference
| Argument | Description | Default | Required |
-|-----------------------------|--------------------------------------------------------------|:-------:|:--------:|
+|-----------------------------|--------------------------------------------------------------------------------------------------------------|:-------:|:--------:|
| `backend.s3` | AWS S3 backend configuration block. | - | false |
| `backend.s3.bucket` | Name of the S3 bucket where Lokomotive stores cluster state. | - | true |
| `backend.s3.key` | Path in the S3 bucket to store the cluster state. | - | true |
| `backend.s3.region` | AWS Region of the S3 bucket. | - | false |
| `backend.s3.aws_creds_path` | Path to the AWS credentials file. | - | false |
-| `backend.s3.dynamodb_table` | Name of the DynamoDB table for locking the cluster state. | - | false |
+| `backend.s3.dynamodb_table` | Name of the DynamoDB table for locking the cluster state. The table must have a primary key named LockID. | - | false |
>NOTE: In order for the installer to configure the credentials for S3 backend either pass them as
environment variables or in the config above.
