Zakaria
92 lines
4.9 KiB
Markdown
92 lines
4.9 KiB
Markdown
# AWS Database Migration Service (DMS)
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**Protocol:** AWS JSON 1.1
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**Signing name:** `dms`
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Floci emulates the replication subnet group lifecycle, which is what
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`aws_dms_replication_subnet_group` needs to plan and apply. Subnets are resolved against
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the emulated EC2 service, so the VPC and Availability Zones a group reports are the ones
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those subnets actually have.
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## Supported Actions
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<!-- floci:actions:start -->
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| Action | Description |
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| --- | --- |
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| `CreateReplicationSubnetGroup` | Creates a replication subnet group from existing EC2 subnets. |
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| `DescribeReplicationSubnetGroups` | Lists replication subnet groups, optionally filtered by identifier. |
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| `DeleteReplicationSubnetGroup` | Deletes the specified replication subnet group. |
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| `ListTagsForResource` | Lists the tags on one or more DMS resource ARNs. |
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| `AddTagsToResource` | Merges tags into the resource, overwriting by key. |
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| `RemoveTagsFromResource` | Removes the named tag keys from the resource. |
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<!-- floci:actions:end -->
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## Behaviour
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- The identifier is stored as a lowercase string, as AWS does, so a group created as
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`MyGroup` is described and deleted as `mygroup`.
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- `ReplicationSubnetGroupIdentifier` must not be `default` and is limited to 255
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alphanumeric characters, periods, underscores, or hyphens.
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- A group must cover at least two Availability Zones. Fewer returns
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`ReplicationSubnetGroupDoesNotCoverEnoughAZs`, as AWS does.
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- Subnets must exist and must all belong to one VPC. Otherwise `InvalidSubnet`.
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- `SubnetGroupStatus` is immediately `Complete`, every subnet reports `Active`,
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`SupportedNetworkTypes` is `["IPV4"]`, and `IsReadOnly` is always `false`: a read-only
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group is one DMS manages for a zero-ETL integration, which Floci does not emulate.
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- `DescribeReplicationSubnetGroups` supports the `replication-subnet-group-id` filter.
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A filter naming a group that does not exist returns `ResourceNotFoundFault`, which is
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how Terraform detects a group deleted outside its state.
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- `DescribeReplicationSubnetGroups` paginates on `MaxRecords` and `Marker`. `MaxRecords`
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defaults to 100 and must be between 20 and 100; a value outside that range is rejected
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with `InvalidParameterValueException` rather than clamped, as AWS does. Results are
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ordered by identifier and `Marker` is an opaque cursor that resumes after the last item
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of the page, so a page stays resumable across groups created or deleted between
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requests. `Marker` is returned
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only when a further page exists, never on the last one.
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- `ReplicationSubnetGroupDescription` is required, must not be blank, and must contain only
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printable characters. A control character such as `0x01` returns
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`InvalidParameterValueException`.
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- A member of the wrong JSON type returns `SerializationException`, as AWS does, rather than
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being coerced. That covers a `Tags` entry whose `Value` is an object, a filter whose
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`Values` is not a list, a non-string element in `ResourceArnList`, `SubnetIds` or
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`TagKeys`, and a non-string identifier. An absent member is still a parameter error,
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not a serialization one.
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- Groups are scoped per account and Region and persist through `StorageFactory`.
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### Tagging
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`Tags` on `CreateReplicationSubnetGroup` are stored with the group, and the tagging trio
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works against the group's ARN, which is
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`arn:aws:dms:<region>:<account>:subgrp:<identifier>`. DMS does not return that ARN from
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`DescribeReplicationSubnetGroups`, so Terraform builds it client side and Floci parses it
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back the same way.
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- `AddTagsToResource` merges by key, so re-tagging an existing key overwrites its value.
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- `RemoveTagsFromResource` removes the named keys and ignores keys that are not present.
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- `ListTagsForResource` accepts either `ResourceArn` or `ResourceArnList`. Each returned
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tag carries its `ResourceArn` only for the `ResourceArnList` form, which is the form
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AWS documents it on.
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- Tag keys are 1 to 128 characters, values at most 256, and neither may start with `aws:`
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or `dms:`.
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- An ARN that is unparseable, names a different DMS resource type, names another account
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or Region, or names a group that does not exist returns `ResourceNotFoundFault`. Tagging
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is not a cross-account or cross-Region operation on AWS and is not one here either.
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- Deleting a group deletes its tags with it.
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## Limitations
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- **Only the subnet group lifecycle is implemented.** Replication instances, endpoints,
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and replication tasks return `UnknownOperationException`.
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- **Tagging covers replication subnet groups only.** The tagging trio is implemented, but
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a `ResourceArn` naming a replication instance, endpoint, or task returns
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`ResourceNotFoundFault` because Floci holds no such resource.
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- **No `ModifyReplicationSubnetGroup`.** A subnet change has to be a delete and recreate.
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See the [AWS DMS API Reference](https://docs.aws.amazon.com/dms/latest/APIReference/Welcome.html).
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## Configuration
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| Variable | Default | Description |
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|---|---|---|
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| `FLOCI_SERVICES_DMS_ENABLED` | `true` | Enable or disable DMS |
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