Dex requires persisting state to perform various tasks such as track refresh tokens, preventing replays, and rotating keys. This document is a summary of the storage configurations supported by dex.
Storage breaches are serious as they can affect applications that rely on dex. Dex saves sensitive data in its backing storage, including signing keys and bcrypt'd passwords. As such, transport security and database ACLs should both be used, no matter which storage option is chosen.
The Custom Resource Definition (CRD) API object was introduced in Kubernetes version 1.7 to replace the Third Party Resource (TPR) extension. CRDs allow dex to run on top of an existing Kubernetes cluster without the need for an external database. While this storage may not be appropriate for a large number of users, it's extremely effective for many Kubernetes use cases.
The rest of this section will explore internal details of how dex uses CRDs. __Admins should not interact with these resources directly__, except while debugging. These resources are only designed to store state and aren't meant to be consumed by end users. For modifying dex's state dynamically see the [API documentation](api.md).
The following is an example of the AuthCode resource managed by dex:
Once the `CustomResourceDefinition` is created, custom resources can be created and stored at a namespace level. The CRD type and the custom resources can be queried, deleted, and edited like any other resource using `kubectl`.
dex requires access to the non-namespaced `CustomResourceDefinition` type. For example, clusters using RBAC authorization would need to create the following roles and bindings:
```
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
name: dex
rules:
- apiGroups: ["dex.coreos.com"] # API group created by dex
resources: ["*"]
verbs: ["*"]
- apiGroups: ["apiextensions.k8s.io"]
resources: ["customresourcedefinitions"]
verbs: ["create"] # To manage its own resources identity must be able to create customresourcedefinitions.
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: dex
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: dex
subjects:
- kind: ServiceAccount
name: dex # Service account assigned to the dex pod.
namespace: dex-namespace # The namespace dex is running in.
If you are currently running dex using TPRs, you will need to [migrate to CRDs](https://github.com/dexidp/dex/blob/v2.17.0/Documentation/storage.md#migrating-from-tprs-to-crds) before you upgrade to a post v2.17 dex. The script mentioned in the instructions can be [found here](https://github.com/dexidp/dex/blob/v2.17.0/scripts/dump-tprs)
The storage configuration is extremely limited since installations running outside a Kubernetes cluster would likely prefer a different storage option. An example configuration for dex running inside Kubernetes:
```
storage:
type: kubernetes
config:
inCluster: true
```
Dex determines the namespace it's running in by parsing the service account token automatically mounted into its pod.
Migrations are performed automatically on the first connection to the SQL server (it does not support rolling back). Because of this dex requires privileges to add and alter the tables for its database.
__NOTE:__ Previous versions of dex required symmetric keys to encrypt certain values before sending them to the database. This feature has not yet been ported to dex v2. If it is added later there may not be a migration path for current v2 users.
### SQLite3
SQLite3 is the recommended storage for users who want to stand up dex quickly. It is __not__ appropriate for real workloads.
The SQLite3 configuration takes a single argument, the database file.
```
storage:
type: sqlite3
config:
file: /var/dex/dex.db
```
Because SQLite3 uses file locks to prevent race conditions, if the ":memory:" value is provided dex will automatically disable support for concurrent database queries.
### Postgres
When using Postgres, admins may want to dedicate a database to dex for the following reasons:
2. Dex's database table names are not configurable; when shared with other applications there may be table name clashes.
```
CREATE DATABASE dex_db;
CREATE USER dex WITH PASSWORD '66964843358242dbaaa7778d8477c288';
GRANT ALL PRIVILEGES ON DATABASE dex_db TO dex;
```
An example config for Postgres setup using these values:
```
storage:
type: postgres
config:
database: dex_db
user: dex
password: 66964843358242dbaaa7778d8477c288
ssl:
mode: verify-ca
caFile: /etc/dex/postgres.ca
```
The SSL "mode" corresponds to the `github.com/lib/pq` package [connection options][psql-conn-options]. If unspecified, dex defaults to the strictest mode "verify-full".
An example config for MySQL setup using these values:
```
storage:
type: mysql
config:
database: dex_db
user: dex
password: 66964843358242dbaaa7778d8477c288
ssl:
mode: custom
caFile: /etc/dex/mysql.ca
```
The SSL "mode" corresponds to the `github.com/go-sql-driver/mysql` package [connection options][mysql-conn-options]. If unspecified, dex defaults to the strictest mode "true".
Each storage implementation bears a large ongoing maintenance cost and needs to be updated every time a feature requires storing a new type. Bugs often require in depth knowledge of the backing software, and much of this work will be done by developers who are not the original author. Changes to dex which add new storage implementations require a strong use case to be considered for inclusion.
