# Migrating to a new machine

Sometimes, for various reasons, you may want to migrate your Mastodon instance from one server to another. Fortunately this is not too difficult of a process, although it may result in some downtime.

{% hint style="info" %}
This guide was written with Ubuntu Server in mind; your mileage may vary for other setups.
{% endhint %}

## Basic steps <a href="#basic-steps" id="basic-steps"></a>

1. Set up a new Mastodon server using the [Production Guide](https://mastodon.gitbook.io/mastodon/jp/admin/install) (however, don’t run `mastodon:setup`).
2. Stop Mastodon on the old server (e.g. `systemctl stop 'mastodon-*.service'`).
3. Dump and load the Postgres database using the instructions below.
4. Copy the `system/` files using the instructions below. (Note: if you’re using S3, you can skip this step.)
5. Copy the `.env.production` file.
6. Run `RAILS_ENV=production bundle exec rails assets:precompile` to compile Mastodon
7. Run `RAILS_ENV=production ./bin/tootctl feeds build` to rebuild the home timelines for each user.
8. Start Mastodon on the new server.
9. Update your DNS settings to point to the new server.
10. Update or copy your Nginx configuration, re-run LetsEncrypt as necessary.
11. Enjoy your new server!

## Detailed steps <a href="#detailed-steps" id="detailed-steps"></a>

### What data needs to be migrated <a href="#what-data-needs-to-be-migrated" id="what-data-needs-to-be-migrated"></a>

At a high level, you’ll need to copy over the following:

* The `~/live/public/system` directory, which contains user-uploaded images and videos (if using S3, you don’t need this)
* The Postgres database (using [pg\_dump](https://www.postgresql.org/docs/9.1/static/backup-dump.html))
* The `~/live/.env.production` file, which contains server config and secrets

Less crucially, you’ll probably also want to copy the following for convenience:

* The nginx config (under `/etc/nginx/sites-available/default`)
* The systemd config files (`/etc/systemd/system/mastodon-*.service`), which may contain your server tweaks and customizations
* The pgbouncer configuration under `/etc/pgbouncer` (if you’re using it)

### Dump and load Postgres <a href="#dump-and-load-postgres" id="dump-and-load-postgres"></a>

Instead of running `mastodon:setup`, we’re going to create an empty Postgres database using the `template0` database (which is useful when restoring a Postgres dump, [as described in the pg\_dump documentation](https://www.postgresql.org/docs/9.1/static/backup-dump.html#BACKUP-DUMP-RESTORE)).

Run this as the `mastodon` user on your old system:

```bash
pg_dump -Fc mastodon_production -f backup.dump
```

Copy the `backup.dump` file over, using `rsync` or `scp`. Then on the new system, create an empty database as the `mastodon` user:

```bash
createdb -T template0 mastodon_production
```

Then import it:

```bash
pg_restore -U mastodon -n public --no-owner --role=mastodon \
  -d mastodon_production backup.dump
```

(Note that if the username is not `mastodon` on the new server, you should change the `-U` AND `--role` values above. It’s okay if the username is different between the two servers.)

### Copy files <a href="#copy-files" id="copy-files"></a>

This will probably take some time, and you’ll want to avoid re-copying unnecessarily, so using `rsync` is recommended. On your old machine, as the `mastodon` user, run:

```bash
rsync -avz ~/live/public/system/ mastodon@example.com:~/live/public/system/
```

You’ll want to re-run this if any of the files on the old server change.

You should also copy over the `.env.production` file, which contains secrets.

Optionally, you may copy over the nginx, systemd, and pgbouncer config files, or rewrite them from scratch.

### During migration <a href="#during-migration" id="during-migration"></a>

You can edit the `~/live/public/500.html` page on the old machine if you want to show a nice error message to let existing users know that a migration is in progress.

You’ll probably also want to set the DNS TTL to something small (30-60 minutes) about a day in advance, so that DNS can propagate quickly once you point it to the new IP address.

### After migrating <a href="#after-migrating" id="after-migrating"></a>

You can check [whatsmydns.net](https://whatsmydns.net/) to see the progress of DNS propagation. To jumpstart the process, you can always edit your own `/etc/hosts` file to point to your new server so you can start playing around with it early.
