Notes on running a personal Mastodon instance

mastodon-notes.md

Personal Mastodon instance

Effective total cost: $3–5/mo

Setup

Decide on an EC2 instance type:

1. At AWS Console → EC2 → Instance Types, filter for ≥1 GB RAM and sort by price.
   • t4g.micro is lowest.
2. Look up what t4g.micro means:
   • t: general-purpose with a burstable CPU quota
   • 4: the current generation
   • g: ARM architecture
   • micro: the second lowest configuration
3. Calculate cost:
   • $6.15/mo when paying hourly
   • $3.59mo when paying annually
   • $2.31/mo when paying every 3 years

Prepare your AWS account:

• Set up an alarm for your estimated monthly bill so you're notified early of any unanticipated expenses.
• Import your SSH public key. (EC2 → us-west-2 → Key pairs)

Have ready:

• a domain name and DNS host
• an outgoing mail server
  • I use AWS SES since it's easy (decent reputation, automatic DKIM, etc.) and inexpensive ($0.01/mo), but any SMTP provider will do, and you could also set up a traditional mail server on the EC2 instance.
• static file storage/hosting
  • I use AWS S3 ($1/mo), but a variety of providers offer "S3-compatible" service, and you could also just use the filesystem on the EC2 instance.

Start an EC2 instance:

1. Launch an instance (EC2 → us-west-2 → Instances) with:
   • Name: Mastodon
   • Image: Ubuntu Server 22.04 LTS (HVM), SSD Volume Type (64-bit ARM)
   • Type: t4g.micro
   • Auto-assign public IP: Disable
   • Security Group:
     • Name: Mastodon
     • SSH from anywhere
     • HTTP from anywhere
     • HTTPS from anywhere
   • Storage: 8 GiB standard (HDD, $0.40/mo)
   • Termination protection: Enable
   • Credit specification: Standard
2. At EC2 → us-west-2 → Elastic IPs, allocate and associate a static IP address.
3. Publish an A record at your preferred DNS host.

Prepare the host:

1. SSH in as ubuntu.

2. Add 1 GB of swap:

   1. Make a swap file at /swapfile.
      1. Create a file that will be used for swap: sudo fallocate -l 1G /swapfile
      2. Only the root user should be able to write and read the swap file. To set the correct permissions type: sudo chmod 600 /swapfile
      3. Use the mkswap utility to set up the file as Linux swap area: sudo mkswap /swapfile
      4. Enable the swap with the following command: sudo swapon /swapfile
      5. To make the change permanent open the /etc/fstab file and append the following line: /swapfile swap swap defaults 0 0
      6. To verify that the swap is active, use either the swapon or the free command as shown below: sudo swapon --show sudo free -h

3. Add swap on compressed RAM:

   1. Install package systemd-zram-generator.
   2. Set zram-fraction = 1 and compression-algorithm = zstd in /etc/systemd/zram-generator.conf.

4. Configure unattended upgrades:

   1. Enable Automatic-Reboot in /etc/apt/apt.conf.d/50unattended-upgrades.

5. Update and upgrade packages.

6. Reboot.

Install Mastodon:

1. Follow Mastodon's instructions.
   • To tune PostgreSQL, set:
     • effective_cache_size = 256MB
   • Tune Node.js to use enough memory:
     • Set export NODE_OPTIONS='--max-old-space-size=1024' in ~mastodon/.bashrc.
   • When editing .env.production, pay particular attention to:
     • LOCAL_DOMAIN
     • SINGLE_USER_MODE
     • SMTP…
     • S3… and AWS…
   • When registering services, set:
     • mastodon-sidekiq: --concurrency 1
     • mastodon-web: MAX_THREADS=2 and WEB_CONCURRENCY=1
2. Schedule the recommended periodic cleanup tasks.
   • Set --concurrency 1 on both tasks.
3. Reboot.
4. Sign in to the web interface and review/configure admin settings.

Try out the setup for a few days/weeks, then commit to a longer payment term:

1. At EC2 → Reserved Instances → Purchase, filter for t4g.micro, sort by effective rate, and purchase a reservation.
2. Wait a few hours for payment processing to complete.
3. At EC2 → Reserved Instances, confirm that the reservation is active.