# AWS Systems Manager

> A toolbox for running, patching and logging into a whole fleet of servers at once.

- Level: Intermediate
- Topics: AWS, Cloud
- URL: https://tidbit.legios.com.ar/aws-systems-manager/
- In Spanish: [AWS Systems Manager](https://tidbit.legios.com.ar/es/aws-systems-manager/)

**AWS Systems Manager** is a set of tools for operating many servers without visiting each one. It works with EC2 instances and also with machines in your own office or data center. On each server runs a small program, the **SSM Agent**, that checks in with AWS and carries out instructions; an IAM role decides what it is allowed to do.

The parts people use most: **Session Manager** opens a terminal on a server from the browser or the command line, with no SSH keys and no open ports, and can log every command typed. Run Command executes the same script on a hundred machines at once. **Patch Manager** installs operating system updates on a schedule. **Parameter Store** keeps configuration values, like a database address or a feature flag, and can store them encrypted with KMS.

It matters because servers that are patched by hand, with SSH keys passed around a team, tend to drift and leak. Systems Manager turns those chores into something repeatable and recorded. For secrets that need automatic rotation, teams often use AWS Secrets Manager instead of Parameter Store; for everyday config, Parameter Store is simpler and its standard tier is free.

## An analogy

The building manager's master console. From one desk they can unlock any apartment, schedule repairs for every floor and keep the list of door codes, without walking the halls with a ring of keys.

## Keep in mind

- Manages EC2 and on-premises servers through the SSM Agent.
- Session Manager gives shell access without SSH keys or open ports.
- Run Command and Patch Manager act on whole fleets at once.
- Parameter Store holds configuration values, optionally encrypted.

## Go deeper

- [What is AWS Systems Manager? (official docs)](https://docs.aws.amazon.com/systems-manager/latest/userguide/what-is-systems-manager.html)
- [AWS Systems Manager Session Manager (official docs)](https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager.html)
- [AWS Systems Manager Parameter Store (official docs)](https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html)

## Related terms

- [Server](https://tidbit.legios.com.ar/server/): A computer whose job is to answer requests from other computers, all day, every day.
- [Amazon EC2](https://tidbit.legios.com.ar/amazon-ec2/): Virtual computers you rent by the hour, in any size, and switch off when done.
- [Data center](https://tidbit.legios.com.ar/data-center/): A building full of servers where the internet, the cloud and AI actually run.
- [IAM](https://tidbit.legios.com.ar/iam/): The rulebook that says who can do what in your AWS account.
- [Command line](https://tidbit.legios.com.ar/command-line/): Controlling a computer by typing text commands instead of clicking icons.
- [Web browser](https://tidbit.legios.com.ar/web-browser/): The app that fetches web pages from the internet and draws them on your screen.
- [SSH](https://tidbit.legios.com.ar/ssh/): An encrypted way to log in to another computer and type commands on it.
- [Port](https://tidbit.legios.com.ar/port/): The numbered door on a computer that says which program a connection is for.