Migrate from Heroku

A Heroku app moves to Sevalla as an application with one process per Procfile entry, Sevalla databases in place of its add-ons, and environment variables in place of its config vars. You recreate the setup while the Heroku app keeps running, copy the data during a short maintenance window, then point the domains at Sevalla.

How Heroku maps to Sevalla

Heroku	Sevalla	Notes
App	Application	Built from a Git repository or a Docker image
Dyno	Instance of a process	Each process runs one or more instances
`web` process type	Web process	Created with the application. Listens on `PORT`, `8080` by default
`worker` and other long-running process types	Background worker	One process per Procfile entry
Release phase (`release`)	Job with the start policy Before deployment	Runs after the build, before the rollout. If it fails, the deployment fails and the previous version keeps running
Heroku Scheduler, clock processes	Cron job	Any cron schedule, in UTC unless you set a time zone
One-off dyno (`heroku run`)	Web terminal	A shell in a running instance of the web process or a background worker
Dyno types (Eco, Basic, Standard, Performance)	Process sizes	H1, S1 to S5, C1 to C4 and M1 to M5, set per process
`heroku ps:scale`, dyno autoscaling	Instances and horizontal autoscaling	Set per web process and background worker
Eco dynos sleeping	Hibernation
Config vars	Environment variables	Available during runtime, build time or both
Buildpacks and stacks	Build strategies	Nixpacks (default), Buildpacks with `heroku/builder:24` or `heroku/builder:22`, Railpack or Dockerfile
GitHub integration, automatic deploys	Automatic deployments	From GitHub, GitLab or Bitbucket
Pipelines and promotion	Pipelines	Stages of applications, promoted from one to the next
Review apps	Preview apps	Created for pull requests in a pipeline
Heroku Postgres	PostgreSQL database
Heroku Key-Value Store (Redis)	Redis or Valkey database
Add-on attachment (`DATABASE_URL`, `REDIS_URL`)	Internal connection	Adds the connection details as environment variables
Bucketeer and other S3 add-ons	Object storage	S3-compatible buckets
Custom domains, Automated Certificate Management	Custom domains	Sevalla issues and renews the SSL certificates
`heroku maintenance:on`	Maintenance mode
`heroku logs --tail`	Logs
Application metrics	Analytics
Deploy hooks (notifications)	Webhooks	Subscribe to the `APP_DEPLOY` event
Teams and collaborators	Users and roles
Platform API and CLI	Sevalla API and CLI

Before you begin

The Heroku CLI, signed in to the account that owns the app.
The app’s code in a repository on GitHub, GitLab or Bitbucket. Sevalla doesn’t deploy from Heroku’s Git remote. See Git providers.
A Sevalla company with a payment method.
The PostgreSQL client tools, at the same major version as Heroku Postgres or newer, if the app uses Heroku Postgres. See Import and export PostgreSQL.
A maintenance window: the Heroku app is in maintenance mode while you copy the data.

Take stock of the Heroku app

Collect what you’ll recreate, with your app’s name in place of storefront:

heroku apps:info --app storefront
heroku addons --app storefront
heroku domains --app storefront
heroku pg:info --app storefront
heroku config --shell --app storefront > heroku.env

apps:info shows the region and the stack. Heroku’s us region runs in northern Virginia and eu in Ireland; the closest Sevalla locations are Ashburn, USA and London, UK. See Locations.
addons lists what becomes a database, a bucket or a third-party service. Services that connect through config vars, such as email or error tracking, keep working when you copy their variables.
pg:info shows the PostgreSQL version (PG Version). Create the Sevalla database with the same version or a newer one.
heroku.env holds every config var as KEY=value. It contains secrets: don’t commit it.
Keep your Procfile at hand: each line becomes a process.

Create the databases

Create the PostgreSQL database

In the sidebar, click Databases, then click Create database. Under Database, choose PostgreSQL and a version at least as new as Heroku’s. Enter orders-db as the Display name, choose the Data center the application will use and a Size with room for the data, then click Create database.

Create the Redis database

If the app uses Heroku Key-Value Store, create a second database the same way: choose Redis, enter storefront-redis as the Display name, and choose the same Data center. See Create a database.

Create the application

Create it from the repository

In the sidebar, click Applications, then click Create > Application. Under Source, click Private repository, then choose the Git provider, the Repository and the Branch. Under Location, choose the same Data center as the databases, choose a Size, and click Create application. The application opens on its Overview tab with the status Not deployed yet: creating an application doesn’t deploy it. See Create an application.

Keep Heroku's buildpacks, if you want

Sevalla builds with Nixpacks by default, which detects most languages without configuration. To build the way Heroku does, click the Settings tab, then click Update build strategy under Build strategy. Choose Buildpacks, set the Pack builder to heroku/builder:24, and click Update build strategy. See Buildpacks.

A web process on H1 can’t have custom domains. If you’ll move a domain, choose a larger size, such as S1.

Connect the databases

Connect PostgreSQL

Click the Networking tab. Under Connected services, click Add internal connection. Choose orders-db as the Service and turn on Add environment variables to the application. Change the key DB_URL to DATABASE_URL, the name your code already reads, and click Add internal connection.

Connect Redis

Add an internal connection to storefront-redis the same way. Its URL is already called REDIS_URL.

The PostgreSQL URL starts with postgres://, like Heroku’s. The Redis URL starts with redis://, where Heroku Key-Value Store’s starts with rediss:// (TLS): if your code passes TLS options for it, such as ssl_cert_reqs=None with redis-py, remove them. See Connect an application.

Add the config vars

Clean up the exported file

In heroku.env, delete DATABASE_URL, REDIS_URL and the other variables that Heroku add-ons set, such as HEROKU_POSTGRESQL_* or REDIS_TLS_URL: the internal connections replace them. Update any value that contains the Heroku domain, such as allowed hosts, to the application’s sevalla.app domain under its name in the page header.

Import the file

Click the Environment variables tab, then click Add environment variables. Click Import .env and choose heroku.env, or paste its contents into a key field. Keep Available during runtime and Available during buildtime selected, and click Add environment variables.

The Add environment variables sheet with key and value rows, Add another, Import .env and the availability options

Don’t add PORT: Sevalla sets it to the web process’s port. See Environment variables.

Recreate the Procfile processes

Procfile entry	Sevalla process	What to set
`web: gunicorn storefront.wsgi`	The existing Web process	Nothing: Nixpacks and Buildpacks start the `web` command from the Procfile. To override it, set the process’s Custom start command.
`worker: celery -A storefront worker`	A Background worker for each entry	The entry’s command as the Custom start command
`release: python manage.py migrate`	A Job with the Start policy Before deployment	The entry’s command as the Custom start command
A Heroku Scheduler job or a `clock` entry	A Cron job	The command as the Custom start command, and its Schedule, for example `/10 * * *` for every 10 minutes

Create each process

On the Processes tab, click Create process. Choose Background worker, Cron job or Job, enter a Name and the Custom start command, set the Start policy (jobs) or the Schedule (cron jobs), choose a Resource, and click Create process. Repeat for each entry.

Remove the release line

Delete the release line from the Procfile and push the change. Nixpacks runs a release entry as a step of the build, not before each deployment; the job runs it at the right time instead.

Commands that use $PORT keep working: Sevalla sets PORT like Heroku does. See Processes.

Copy the PostgreSQL data

Stop writes on Heroku

Turn on maintenance mode, which answers visitors with Heroku’s maintenance page, and stop the workers:

heroku maintenance:on --app storefront
heroku ps:scale worker=0 --app storefront

Download a backup

heroku pg:backups:capture --app storefront
heroku pg:backups:download --app storefront

The backup downloads as latest.dump, a custom-format archive.

Open the Sevalla database to your computer

In the sidebar, click Databases, then click orders-db. Click the Networking tab, click Enable under External connection, then click Enable in the dialog. Copy the External hostname, External port and password. See Enable the external connection.

Restore the backup

Restore latest.dump with pg_restore, as in Import a database.

To rehearse, run these steps once without maintenance mode, deploy, and test on the sevalla.app domain. For the real cutover, empty the database first, for example with pg_restore’s --clean --if-exists options, so the restore doesn’t collide with the rehearsal’s tables.

Copy the Redis data

Skip this when Redis holds only caches or jobs you can lose: the application refills it. Heroku Key-Value Store doesn’t document an export, so copy the keys with DUMP and RESTORE:

Open the Redis database to your computer

Enable the external connection of the Sevalla Redis database, as for PostgreSQL, and copy its External connection URL.

Copy the keys

Save this script, then run it with both URLs:

copy_redis.py

import os

import redis

# Heroku Key-Value Store uses TLS with a self-signed certificate.
source = redis.from_url(os.environ["HEROKU_REDIS_URL"], ssl_cert_reqs=None)
target = redis.from_url(os.environ["SEVALLA_REDIS_URL"])

copied = 0
for key in source.scan_iter(count=1000):
    data = source.dump(key)
    if data is None:  # the key expired during the copy
        continue
    ttl = source.pttl(key)
    target.restore(key, max(ttl, 0), data, replace=True)
    copied += 1
print(f"Copied {copied} keys")

pip install redis
HEROKU_REDIS_URL="$(heroku config:get REDIS_URL --app storefront)" \
SEVALLA_REDIS_URL="redis://:<password>@<external hostname>:<external port>/0" \
python copy_redis.py

The script copies database 0, the one in both URLs, and keeps each key’s expiry. If RESTORE fails with DUMP payload version or checksum are wrong, the Sevalla database runs an older version than Heroku’s: create it with a newer version. See Import and export Redis.

Deploy and verify

Deploy

On the application’s Overview tab, click Deploy now under Recent deployments, check the Branch, and click Deploy.

Check the deployment

On the Deployments tab, wait for the status Deployed. The build log shows each job’s result, such as Migrate has been successful.

Test the application

Click the domain under the application’s name and test the critical paths: sign-in, a write to the database, a background task. On the Processes tab, the web process and the background workers show Running.

Turn on auto-deploy

To deploy every push to the branch automatically, click the Settings tab, then click Update auto-deploy in the Auto-deploy section. Turn on Auto-deploy and click Update auto-deploy. See Deployments.

Move the custom domains

Add each domain

On the application’s Domains tab, click Add custom domain, enter the domain in Domain name, for example shop.example.com, and click Add custom domain.

Verify it

Add the ownership and certificate records that Sevalla shows at your DNS provider. Heroku keeps serving the domain meanwhile. When the domain’s status changes to Pointing, its certificate is ready. See Verify the domain.

Point it at Sevalla

Replace the record that points at Heroku (a CNAME to a herokudns.com target) with the pointing record that Sevalla shows. The status changes to Active when Sevalla sees it. See Point the domain.

Add the custom domains to any setting that lists allowed hosts, such as Django’s ALLOWED_HOSTS, then deploy.

Shut down the Heroku app

When the domains are Active and traffic reaches Sevalla:

Disable the external connections you opened: on each database’s Networking tab, click Disable under External connection, then click Disable in the dialog.
Keep latest.dump until you no longer need it.
Stop the Heroku app with heroku ps:scale web=0 --app storefront, and delete it with heroku apps:destroy --app storefront once you’re sure. Deleting a Heroku app deletes its add-ons and their data.

To repeat the setup for staging and review apps, put the applications in a pipeline and turn on preview apps.

Migrate

JavaScript

Python

How Heroku maps to Sevalla

Before you begin

Take stock of the Heroku app

Create the databases

Create the application

Connect the databases

Add the config vars

Recreate the Procfile processes

Copy the PostgreSQL data

Copy the Redis data

Deploy and verify

Move the custom domains

Shut down the Heroku app

​How Heroku maps to Sevalla

​Before you begin

​Take stock of the Heroku app

​Create the databases

​Create the application

​Connect the databases

​Add the config vars

​Recreate the Procfile processes

​Copy the PostgreSQL data

​Copy the Redis data

​Deploy and verify

​Move the custom domains

​Shut down the Heroku app

How Heroku maps to Sevalla

Before you begin

Take stock of the Heroku app

Create the databases

Create the application

Connect the databases

Add the config vars

Recreate the Procfile processes

Copy the PostgreSQL data

Copy the Redis data

Deploy and verify

Move the custom domains

Shut down the Heroku app