---
title: "Self-Host Dex"
description: "Run dex-server-zd next to your Workers on your own object storage. What it needs, how it stores Flows, what happens when a node fails, and how to start it."
canonical_url: "https://docs.superdurable.io/components/self-host/"
source: "docs/content/components/self-host.mdx"
locale: "en"
---

> Index of every page for AI agents: https://docs.superdurable.io/llms.txt

# Self-Host Dex

You run **dex-server-zd** next to your Workers. It keeps every Flow in object storage, such as Amazon S3, and a standby can take over when the active node stops. You configure authentication, TLS, retention, and monitoring yourself.

The [Sustainable Use License](https://docs.superdurable.io/intro/limits.md#license) lets you run Dex for your own business.

<a id="dependencies"></a>

## What it needs

| Dependency                                                  | Required                 | What it gives you                                                                                                                        |
| ----------------------------------------------------------- | ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------- |
| Object storage, such as Amazon S3 or an S3-compatible store | Yes, or db9 in its place | The record of every Flow                                                                                                                 |
| A PostgreSQL or ParadeDB search backend                     | No                       | Large or frequent searches served from SQL. See [Search backends](https://docs.superdurable.io/reference/server/search.md).              |
| A PostgreSQL Attribute Store                                | No                       | Copies of selected Attributes in your own tables. See [Dex and Your Database](https://docs.superdurable.io/components/your-database.md). |
| A metrics listener                                          | No                       | Prometheus metrics. See [Metrics](https://docs.superdurable.io/reference/server/metrics.md).                                             |

db9 is the PostgreSQL-compatible option for Dex Server's own state; stock PostgreSQL is not supported. [Dex Server dependencies](https://docs.superdurable.io/components/server.md#dependencies) explains it.

<a id="how-it-works"></a>

## How it stores Flows

Object storage is the record. Dex Server keeps a local store only as a cache, and a node rebuilds that cache from object storage after a restart. When Dex reports that something happened, such as a started Flow or a SYNC Step result, Dex has already written it to object storage.

One active process serves a cluster. It holds a lease in object storage, so a second process cannot write at the same time. Its capacity is the cluster's ceiling. [Limits](https://docs.superdurable.io/intro/limits.md) and [Performance](https://docs.superdurable.io/intro/performance.md) give the numbers.

<a id="failover"></a>

## When a node fails

A standby takes over after the active node's lease expires, plus 1 second. The lease is 10 seconds by default. Without a standby, the node serves again only after it restarts. A graceful step down releases the lease, so a standby takes over at once.

After a takeover, every Step attempt that a Worker had received runs again, and each one uses a retry, except some ASYNC attempts that keep their attempt number. So the external calls in a Step need an [idempotency key](https://docs.superdurable.io/concepts/step.md#idempotency-keys). [Failover and Deploys](https://docs.superdurable.io/concepts/failover-and-deploys.md) lists what runs again for each event, and [Lease, hot standby, and step down](https://docs.superdurable.io/reference/server/high-availability.md) gives the timings.

<a id="run-it"></a>

## Run it

In production, run **dex-server-zd serve** with one YAML configuration file. The release publishes binaries and a container image. On Kubernetes, run it as a StatefulSet.

```bash
dex-server-zd serve --config /etc/dex-server-zd/config.yaml
```

To run one production node on local disk without external object storage, run **dex-server-zd local**. It keeps an embedded object store in its data directory and has no standby.

[Run Dex in Production](https://docs.superdurable.io/components/production.md#minimal-configuration) has a minimal configuration with authentication on.

## Next

- [Run Dex in Production](https://docs.superdurable.io/components/production.md): the checklist before launch.
- [Dex Server](https://docs.superdurable.io/components/server.md): the full page on the server and its dependencies.