Can't change RDS Postgres major version from the AWS console? - amazon-rds

Question

I have an RDS Postgres database, currently sitting at version 14.3.
I want to schedule a major version upgrade to 14.5 to happen during the maintenance window.
I want to do this manually via the console, because last time I did a major version of the Postgres version by changing the CDK definition, the deploy command applied the DB version change immediately, resulting in a few minutes downtime of the database (manifesting as connection errors in the application connecting to the database).
When I go into the AWS RDS console, do a "modify" action and select the "DB Engine Version" - it only shows one option, which is the current DB version: "14.3".
According to the RDS doco 14.4, 14.5. and 14.6 are all valid upgrade targets: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.PostgreSQL.html#USER_UpgradeDBInstance.PostgreSQL.MajorVersion
Also, when I do aws rds --profile raido-prod describe-db-engine-versions --engine postgres --engine-version 14.3 it shows those versions in the ValidUpgradeTarget collection.
Using CDK version 2.63.0
Database CDK code:
// starting with 14.3 to test the manual upgrade process
const engineVersion14_3 = PostgresEngineVersion.VER_14_3;
const dbParameterGroup14_3 = new ParameterGroup(this, 'Postgres_14_3', {
description: "RaidoDB postgres " + engineVersion14_3.postgresFullVersion,
engine: DatabaseInstanceEngine.postgres({
version: engineVersion14_3,
}),
parameters: {
// none we need right now
},
});
/* Note that even after this stack has been deployed, this param group
will not be created, I guess it will only be created when it's attached
to an instance? */
const engineVersion14_5 = PostgresEngineVersion.VER_14_5;
// CDK strips out underbars from name, hoping periods will remain
const dbParameterGroup14_5 = new ParameterGroup(this, 'Postgres.14.5.', {
description: "RaidoDB postgres " + engineVersion14_3.postgresFullVersion,
engine: DatabaseInstanceEngine.postgres({
version: engineVersion14_5,
}),
parameters: {
// none we need right now
},
});
this.pgInstance = new DatabaseInstance(this, 'DbInstance', {
databaseName: this.dbName,
instanceIdentifier: this.dbName,
credentials: Credentials.fromSecret(
this.raidoDbSecret,
this.userName,
),
vpc: props.vpc,
vpcSubnets: {
subnetGroupName: props.subnetGroupName,
},
publiclyAccessible: false,
subnetGroup: dbSubnetGroup,
multiAz: false,
availabilityZone: undefined,
securityGroups: [props.securityGroup],
/* Should we size a bigger instance for prod?
Plan is to wait until its needed - there will be some downtime for
changing these. There's also the "auto" thing. */
allocatedStorage: 20,
instanceType: InstanceType.of(InstanceClass.T4G, InstanceSize.SMALL),
engine: DatabaseInstanceEngine.postgres({
version: engineVersion14_3,
}),
parameterGroup: dbParameterGroup14_3,
/* Not sure what this does, changing it to true didn't allow me to change
the version in the console. */
allowMajorVersionUpgrade: true,
/* 14.3.x -> 14.3.x+1 will happen automatically in maintenance window,
with potential downtime. */
autoMinorVersionUpgrade: true,
// longer in prod
backupRetention: Duration.days(30),
/* This enables DB termination protection.
When stack is destroyed, db will be detached from stack but not deleted.
*/
removalPolicy: RemovalPolicy.RETAIN,
// explain and document the threat model before changing this
storageEncrypted: false,
/* "Enhanced monitoring"."
I turned this on while trying to figure out how to change the DB version.
I still don't think we should have it enabled until we know how/when we'll
use it - because it costs money in CloudWatch Logging, Metric fees and
performance (execution and logging of the metrics from the DB server).
*/
monitoringInterval: Duration.minutes(1),
monitoringRole: props.monitoringRole,
/* Useful for identifying expensive queries and missing indexes.
Retention default of 7 days is fine. */
enablePerformanceInsights: true,
// UTC
preferredBackupWindow: '11:00-11:30',
preferredMaintenanceWindow: 'Sun:12:00-Sun:13:00',
});
So, the question: What do I need to do in order to be able to schedule the DB version upgrade in the maintenance window?

Answer 1

I made a lot of changes during the day trying to diagnose the issue before I posted this question, thinking I must be doing something wrong.
When I came back to work the next day, the modify screen DB Engine Version field contained the upgrade options I was originally expecting.
Below is my documentation of the issue (unfortunately, our CDK repo is not public):
Carried out by STO, CDK version was 2.63.0.
This page documents my attempt to manually schedule the DB version upgrade
using the console for application during the maintenance window.
We need to figure out how to do this since the DB upgrade process results in a
few minutes of downtime, so we'd prefer to avoid doing it in-hours.
It's preferred that we figure out how to schedule the upgrade - if the choice
comes down to asking team members to work outside or hours or accept
downtime - we will generally choose to have the downtime during business hours.
Note that that Postgres instance create time is:
Sat Jan 28 2023 10:34:32 GMT+1000
Action plan
in the RDS console
Modify DB instance: raido
DB engine version: change 14.3 to 14.5
save and select to "schedule upgrade for maintenance window" (as
opposed to "apply immediately")
Actions taken
2023-02-02
When I tried to just go in and change it manually in the AWS console, the only
option presented on the "modify" screen was 14.3 - there was nothing to
change the version to.
I tried creating a 14.5 param group in CDK, but it just ignored me, didn't
create the param group I'm guessing because it's expected to actually be
attached to a DB.
Tried copying and creating a new param group to change the version, but there's
no "version" param in the param group.
Tried manually create a db of version 14.5 "sto-manual-14-5", but after the
DB was reported successfully created (as 14.5) - "14.3" is still the only
option in the "modify" screen for raido-db.
Tried creating a t3.micro in case t4g ws the problem - no good.
Tried disabling minor version auto-upgrade - no good.
Note that 14.6 is the current most recent version, both manually created 14.3
and 14.5 databases presented no other versions to upgrade to - so this problem
doesn't seem to be related to the CDK.
List available upgrades: aws rds --profile raido-prod describe-db-engine-versions --engine postgres --engine-version 14.3
Shows 14.4, 14.5 and 14.6 as valid target versions.
This page also shows the the versions should be able to be upgraded to, as at
2023-02-02: https://docs.amazonaws.cn/en_us/AmazonRDS/latest/UserGuide/USER_UpgradeDBInstance.PostgreSQL.html#USER_UpgradeDBInstance.PostgreSQL.MajorVersion
After all this, I noticed that we had the instance declared as
allowMajorVersionUpgrade: false, so I changed that to true and deployed,
but still can't select any other versions.
Also tried aws rds --profile raido-prod describe-pending-maintenance-actions
but it showed no pending actions.
I found this SO answer talking about RDS problems with T3 instances (note, I
have previously upgraded major versions of T3 RDS postgres instances):
https://stackoverflow.com/a/69295017/924597
On the manually created t3.micro instance, I tried upgrading the instance size
to a standard large instance. Didn't work.
Found this SO answer talking about the problem being related to having
outstanding "recommended actions" entries:
https://stackoverflow.com/a/75236812/924597
We did have an entry talking about "enhanced monitoring".
Tried enabling "enhanced monitoring" via the CDK, because it was listed as
a "recommended action" on the RDS console.
After deploying the CDK stack, the console showed the enhanced monitoring was
enabled, but the "recommended action" to enable it was still listed.
At this point, the console still showed 14.3 as the only option in the list on
the modify screen.
Posted to StackOverflow: Can't change RDS Postgres major version from the AWS console?
Posted to AWS repost: https://repost.aws/questions/QU4zuJeb9OShGfVISX6_Kx4w/
Stopped work for the day.
2023-02-03
In the morning, the RDS console no longer shows the "recommended action" to
enabled enhanced monitoring.
The modify screen now shows "14.3, 14.4, 14.5 and 14.6" as options for the
DB Engine Verison (as expected and orginally desired).
Given the number of changes I tried above, I'm not sure what, if any of them
may have caused the console to start displaying the correct options.
It may have been a temporary issue with RDS, or AWS support may have seen my
question on the AWS repost forum and done something to the account.
Note that I did not raise a formal support request via the AWS console.
I wanted to try and confirm if the enhanced monitoring was the cause of the
issue, so I changed the CDK back (there is no "enhance monitoring" flag, I
just commented out the code that set the monitoring role and interval).
After deploying the CDK stack, there was no change to the RDS instance -
enhanced monitoring was still enabled.
I did a manual modify via the RDS console to disable enhanced monitoring.
The change did apply and was visible in the consle, but the "recommended
actions" list did not have any issues.
At this point I had to attend a bunch of meetings, lunch, etc.
When I came back after lunch, the "recommended actions" list now shows an
"enhanced monitoring" entry.
But the modify console page still shows the 14.3 - 14.6 DB engine options, so
I don't think "enhanced monitoring" was the cause of the problem.
I scheduled the major version upgrade (14.3 -> 14.5, because 14.6 is not yet
supported by the CDK) for the next maintenance window.
Analysis
My guess is that the issue was caused by having allowMajorVersionUpgrade set
to false. I think changing it to true is what caused the other
version options to eventually show up on the modify page. I think the
reason the options didn't show up on the modify page after depoloying the
CDK change is down to waiting for an eventual consistency conflict to converge.