rds on Alperen Doc

relational-database-service

Mon, 01 Jan 0001 00:00:00 +0000

RDS: Relational Database Service#

Amazon RDS (Relational Database Service) is AWS’ managed database service. If you don’t want to manage/host a database server yourself, you can let AWS handle provisioning, backups, patching, and monitoring. You get a database you can connect to with (nearly) zero operational overhead.

That said, RDS can get very expensive, especially if you have lots of data or need to operate in multiple AZs. But for many applications, the cost of a managed service is reasonable, and far outweighed by its benefits.

create-a-postgresql-database-in-aws

Mon, 01 Jan 0001 00:00:00 +0000

Create a PostgreSQL Database#

Alright, let’s get a database set up and ready to use.

Assignment#

PatientPing’s data needs a proper home. Everyone is in constant fear that the next time Zach reboots things, we’re going to lose data.

Create a PostgreSQL RDS instance (patientping-db) in your patientping VPC’s private subnets (no public access!).

Cost check: A db.t3.micro instance costs about $0.018 per hour (~$13/month). Be sure to delete this when you’re done. AWS only allows you to “pause” an RDS instance for a time, then it starts it up again.

aws-connect-to-your-database

Mon, 01 Jan 0001 00:00:00 +0000

Connect to Your Database#

Now that you have a database, we need our application server to connect to it. After all, they’re in different subnets (public vs. private) in the same VPC. AWS adds a local route for your VPC CIDR by default, so subnets in that VPC can route to one another.

The key is security groups. Remember, security groups are like stateful firewalls that control traffic to and from your resources.

aws-connect-app-to-database

Mon, 01 Jan 0001 00:00:00 +0000

Connect App to Database#

We’ve seen that we can use psql from our EC2 instance to connect to the Postgres DB running in RDS. That’s no small feat; a bunch of things had to be configured just right for it to work.

The good news is that it will take only one more small step to get the PatientPing app communicating with the database automatically. Instead of using psql manually, we’ll set a DATABASE_URL environment variable that the Python app can read when it starts up!

rds-backups

Mon, 01 Jan 0001 00:00:00 +0000

RDS Backups#

One is none, two is one.

Backups are important. We’re going to break things in creative, irreparable ways from time to time, and RDS can automatically back up your database.

Daily backups: Taken during your preferred backup window (you can set this)
Transaction logs: Continuously backed up (enables point-in-time recovery)
Retention period: Configurable (1-35 days for most engines)
Storage: Backups stored in S3, separate from your database instance
Cost: Storage for backups is charged separately (about $0.095 per GB per month)

Cost check: Backups cost money. A 7-day retention period means you’re storing 7 days of backups (at ~$0.095/GB/month). For a 20 GB database that can be ~140 GB of backup storage. Monitor backup costs, and reduce retention or delete snapshots when done.

create-read-replicas-for-scalability

Mon, 01 Jan 0001 00:00:00 +0000

Read Replicas#

Think about how Discord or Slack works for a moment. There are chat channels filled with tons of users. Do you, as a user, read more or write more to the server?

Unless you’re an incredibly chatty person, you’re going to read waaaaaay more messages than you send. Wouldn’t it be nice to offload those reads from an expensive primary database to a cheaper server?

Enter read replicas.

rds-general-knowledge

Mon, 01 Jan 0001 00:00:00 +0000

RDS Storage and IOPS#

When you create an RDS instance, you choose a type and amount of storage. AWS offers different storage types optimized for different workloads. Let’s go over them.

General Purpose SSD (`gp3`)#

This is the recommended default for most production workloads. It’s a good balance of performance and cost:

Baseline performance: 3,000 IOPS (Input/Output Operations Per Second)
Scalable: Can provision up to 16,000 IOPS if needed
Cost-effective: Lower cost than provisioned IOPS
Use case: Most applications, up to moderate I/O requirements

Provisioned IOPS SSD (`io1`/`io2`)#

This is for demanding workloads that need guaranteed performance:

rds on Alperen Doc

relational-database-service

RDS: Relational Database Service#

create-a-postgresql-database-in-aws

Create a PostgreSQL Database#

Assignment#

aws-connect-to-your-database

Connect to Your Database#

aws-connect-app-to-database

Connect App to Database#

rds-backups

RDS Backups#

create-read-replicas-for-scalability

Read Replicas#

rds-general-knowledge

RDS Storage and IOPS#

General Purpose SSD (gp3)#

Provisioned IOPS SSD (io1/io2)#

General Purpose SSD (`gp3`)#

Provisioned IOPS SSD (`io1`/`io2`)#