Julian Sommer
4.0 KiB
Engines
Spinifex offers PostgreSQL and MariaDB. Each DB instance is one dedicated system-owned VM running the engine directly, launched from a platform AMI and hidden from the customer's EC2 API. Engine is fixed at create: there is no in-place engine change, no cross-engine snapshot restore and no migration between the two.
mysql is not an accepted engine and is not an alias for mariadb. MariaDB is offered under its own AWS engine name, exactly as AWS RDS offers it, so a client — including Terraform's aws_db_instance — must set engine = "mariadb".
Engine versions are pinned per engine. An EngineVersion naming anything but the pin is rejected, including a narrower minor version, because the AMI makes no promise about which minor it carries.
The endpoint is private
The engine is reached over a customer-account ENI injected into a subnet of the DB subnet group, so the endpoint is reachable from inside the VPC only. The DB VM has other NICs that no customer security group governs, and the engine binds none of them — the port is not open there at all, rather than open and gated.
TLS is required by default
Both engines enforce encrypted connections by default: rds.force_ssl on PostgreSQL and require_secure_transport on MariaDB. For MariaDB this is a deliberate divergence from AWS, which leaves it off. Both are boolean, modifiable and dynamic, so setting either to 0 in a parameter group restores plaintext without a reboot.
Rejected parameters
A parameter whose omission would create a false safety, security or availability guarantee is rejected with InvalidParameterValue rather than silently dropped.
| Parameter | Why it is rejected |
|---|---|
MultiAZ=true |
Single-AZ platform; a standby would not exist |
PubliclyAccessible=true |
The endpoint is a private VPC address |
StorageEncrypted=false |
Unencrypted storage is not offered |
EnableIAMDatabaseAuthentication |
IAM database authentication is not implemented |
Iops, StorageThroughput, StorageType ≠ gp3 |
Provisioned performance classes are not implemented |
KmsKeyId, TdeCredentialArn |
Storage is encrypted with the cluster key, not a customer-managed one |
AvailabilityZone |
The platform exposes a single zone |
AvailabilityZoneGroup (orderable options) |
It selects a zone or local-zone group, and naming a zone is already refused |
DBSecurityGroups |
EC2-Classic security groups — use VpcSecurityGroupIds |
DBClusterIdentifier, DBClusterSnapshotIdentifier |
Clustered engines are not offered |
EnableCloudwatchLogsExports |
Log export is not implemented |
EngineVersion other than the engine's pin; on modify, any EngineVersion and Engine |
No in-place engine or version change |
Engine=mysql (and Aurora engines) |
Oracle MySQL is not offered; mariadb is a distinct engine, not an alias for it |
NewDBInstanceIdentifier |
The identifier is the DNS label and the KV key |
DBPortNumber, DBSubnetGroupName on modify |
Both would move the endpoint |
MaxAllocatedStorage |
Storage autoscaling is not implemented |
ManageMasterUserPassword, RotateMasterUserPassword |
Secrets Manager integration is not offered |
CACertificateIdentifier |
The serving certificate is minted from the cluster CA |
Domain, DomainFqdn |
Active Directory domain join is not offered |
OptionGroupName |
Option groups are not offered |
CustomIamInstanceProfile |
The DB VM's instance profile is platform-owned |
EnableCustomerOwnedIp |
An Outposts feature |
ForceFailover (reboot) |
No standby to fail over to |
DBSnapshotIdentifier (stop) |
Snapshot-on-stop is not implemented |
DBInstanceAutomatedBackupsArn (DescribeDBInstanceAutomatedBackups) |
Cross-region automated backup replication is not offered, so no replicated backup has an ARN |
dbi-resource-id filter (DescribeDBSnapshots, DescribeDBInstanceAutomatedBackups) |
Snapshots and automated backups do not record their source instance's resource ID |