Skip to main content

Create Stateful Elastic Block Storage on AWS.

Project description

Stateful Elastic Block Storage (sebs)

Sebs was created for the situation where you need to stick a stateful application in an AutoScaling group with a max size of 1. Sebs will make sure that if the instance is recreated that the previous volume is reattached back to the instance regardless of which AZ the instance is recreated in.

Why

A single instance ASG is good protection in the event that the instance is retired. It can also help enable rolling upgrades and DR in the event that the AZ your instance is in goes down.

Prerequisites

  • python3
  • EC2 Instance Profile with access to create/delete snapshots and volumes.

Example IAM Policy

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DetachVolume",
                "ec2:AttachVolume",
                "ec2:DeleteVolume",
                "ec2:DeleteSnapshot",
                "ec2:CreateTags",
                "ec2:CreateSnapshot",
                "ec2:CreateVolume"
            ],
            "Resource": [
                "arn:aws:ec2:*:*:instance/*",
                "arn:aws:ec2:*::snapshot/*",
                "arn:aws:ec2:*:*:volume/*"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ec2:DescribeVolumes",
                "ec2:DescribeSnapshots"
            ],
            "Resource": "*"
        }
    ]
}

Installing

Sebs should be run from an EC2 instance and can be run from userdata or any CaC tool. Sebs can be installed from pip or GitHub.

From pip

pip install sebs

From GitHub

python3 -m pip install git+https://github.com/DontShaveTheYak/sebs.git#egg=sebs

Usage

sebs
usage: sebs [-h] -b BACKUP [-n NAME] [-v] [--version]

optional arguments:
  -h, --help            show this help message and exit
  -b BACKUP, --backup BACKUP
                        <Required> List of Devices to Backup
  -n NAME, --name NAME  <Optional> specify a your app name.
  -v, --verbose         Verbosity (-v, -vv, etc)
  --version             show program's version number and exit

Note: If you are going to have more than one instance in a single region use sebs, then you need to pass in a name.

sebs -b /dev/xvdz -n ${MY_APP_NAME}

Here is an example userdata script

#!/bin/bash
exec > >(tee /var/log/user-data.log|logger -t user-data -s 2>/dev/console) 2>&1

echo "Running Sebs"
yum install python3 -y
python3 -m pip install sebs

# On RHEL and Amazon Linux2 /usr/local/bin is not in the path for root user.
/usr/local/bin/sebs -b /dev/xvdz -n example-app

echo 'Waiting on device /dev/xvdz to be available.'
while [ ! -e /dev/xvdz ] ; do sleep 1 ; done
echo 'Device is ready.'

On first run sebs will mark the volume mounted at /dev/xvdz with a control tag. If the instance is re-created sebs will look for a volume with the control tag and if found it will then mount that volume to the instance as the same device as before.

Contributing

Please read CONTRIBUTING.md.

Versioning

We use SemVer for versioning. For the versions available, see the tags on this repository.

To see what has changed see the CHANGELOG.

License

This project is licensed under the GPLv3 License - see the LICENSE file for details

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for sebs, version 0.5.1
Filename, size File type Python version Upload date Hashes
Filename, size sebs-0.5.1-py3-none-any.whl (29.1 kB) File type Wheel Python version py3 Upload date Hashes View
Filename, size sebs-0.5.1.tar.gz (14.8 kB) File type Source Python version None Upload date Hashes View

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page