zitadel/docs/docs/self-hosting/manage/cli/mirror.mdx

---
title: Mirror data to another database
sidebar_label: Mirror command
---

The `mirror` command allows you to do database to database migrations. This functionality is useful to copy data from one database to another.

The data can be mirrored to multiple database without influencing each other.

## Use cases

Migrate from cockroachdb to postgres or vice versa.

Replicate data to a secondary environment for testing.

## Prerequisites

You need an existing source database, most probably the database ZITADEL currently serves traffic from.

To mirror the data the destination database needs to be initialized and setup without an instance.

### Start the destination database 

Follow one of the following guides to start the database:

* [Linux](/docs/self-hosting/deploy/linux#run-postgresql)
* [MacOS](/docs/self-hosting/deploy/macos#install-postgresql)

Or use the following commands for [Docker Compose](/docs/self-hosting/deploy/compose)

```bash
# Download the docker compose example configuration.
wget https://raw.githubusercontent.com/zitadel/zitadel/main/docs/docs/self-hosting/deploy/docker-compose.yaml

# Run the database and application containers.
docker compose up db --detach
```

## Example

The following commands setup the database as described above. See [configuration](#configuration) for more details about the configuration options.

```bash
zitadel init --config /path/to/your/new/config.yaml
zitadel setup --for-mirror --config /path/to/your/new/config.yaml # make sure to set --tlsMode and masterkey analog to your current deployment
zitadel mirror --system --config /path/to/your/mirror/config.yaml # make sure to set --tlsMode and masterkey analog to your current deployment
```

## Usage

The general syntax for the mirror command is:

```bash
zitadel mirror [flags]

Flags:
  -h, --help                     help for mirror

      --config stringArray       path to config file to overwrite system defaults

      --ignore-previous          ignores previous migrations of the events table. This flag should be used if you manually dropped previously mirrored events.
      --replace                  replaces all data of the following tables for the provided instances or all if the `--system`-flag is set:
                                 * system.assets
                                 * auth.auth_requests
                                 * eventstore.unique_constraints
                                 The should be provided if you want to execute the mirror command multiple times so that the static data are also mirrored to prevent inconsistent states.

      --instance strings         id or comma separated ids of the instance(s) to migrate. Either this or the `--system`-flag must be set. Make sure to always use the same flag if you execute the command multiple times.
      --system                   migrates the whole system. Either this or the `--instance`-flag must be set. Make sure to always use the same flag if you execute the command multiple times.

# For the flags below use the same configuration you also use in the current deployment

      --masterkey string         masterkey as argument for en/decryption keys
  -m, --masterkeyFile string     path to the masterkey for en/decryption keys
      --masterkeyFromEnv         read masterkey for en/decryption keys from environment variable (ZITADEL_MASTERKEY)
      --tlsMode externalSecure   start ZITADEL with (enabled), without (disabled) TLS or external component e.g. reverse proxy (external) terminating TLS, this flag will overwrite externalSecure and `tls.enabled` in configs files
```

## Configuration

```yaml
# The source database the data are copied from. Use either cockroach or postgres, by default cockroach is used
Source:
  cockroach:
    Host: localhost # ZITADEL_SOURCE_COCKROACH_HOST
    Port: 26257 # ZITADEL_SOURCE_COCKROACH_PORT
    Database: zitadel # ZITADEL_SOURCE_COCKROACH_DATABASE
    MaxOpenConns: 6 # ZITADEL_SOURCE_COCKROACH_MAXOPENCONNS
    MaxIdleConns: 6 # ZITADEL_SOURCE_COCKROACH_MAXIDLECONNS
    EventPushConnRatio: 0.33 # ZITADEL_SOURCE_COCKROACH_EVENTPUSHCONNRATIO
    ProjectionSpoolerConnRatio: 0.33 # ZITADEL_SOURCE_COCKROACH_PROJECTIONSPOOLERCONNRATIO
    MaxConnLifetime: 30m # ZITADEL_SOURCE_COCKROACH_MAXCONNLIFETIME
    MaxConnIdleTime: 5m # ZITADEL_SOURCE_COCKROACH_MAXCONNIDLETIME
    Options: "" # ZITADEL_SOURCE_COCKROACH_OPTIONS
    User:
      Username: zitadel # ZITADEL_SOURCE_COCKROACH_USER_USERNAME
      Password: "" # ZITADEL_SOURCE_COCKROACH_USER_PASSWORD
      SSL:
        Mode: disable # ZITADEL_SOURCE_COCKROACH_USER_SSL_MODE
        RootCert: "" # ZITADEL_SOURCE_COCKROACH_USER_SSL_ROOTCERT
        Cert: "" # ZITADEL_SOURCE_COCKROACH_USER_SSL_CERT
        Key: "" # ZITADEL_SOURCE_COCKROACH_USER_SSL_KEY
  # Postgres is used as soon as a value is set
  # The values describe the possible fields to set values
  postgres:
    Host: # ZITADEL_SOURCE_POSTGRES_HOST
    Port: # ZITADEL_SOURCE_POSTGRES_PORT
    Database: # ZITADEL_SOURCE_POSTGRES_DATABASE
    MaxOpenConns: # ZITADEL_SOURCE_POSTGRES_MAXOPENCONNS
    MaxIdleConns: # ZITADEL_SOURCE_POSTGRES_MAXIDLECONNS
    MaxConnLifetime: # ZITADEL_SOURCE_POSTGRES_MAXCONNLIFETIME
    MaxConnIdleTime: # ZITADEL_SOURCE_POSTGRES_MAXCONNIDLETIME
    Options: # ZITADEL_SOURCE_POSTGRES_OPTIONS
    User:
      Username: # ZITADEL_SOURCE_POSTGRES_USER_USERNAME
      Password: # ZITADEL_SOURCE_POSTGRES_USER_PASSWORD
      SSL:
        Mode: # ZITADEL_SOURCE_POSTGRES_USER_SSL_MODE
        RootCert: # ZITADEL_SOURCE_POSTGRES_USER_SSL_ROOTCERT
        Cert: # ZITADEL_SOURCE_POSTGRES_USER_SSL_CERT
        Key: # ZITADEL_SOURCE_POSTGRES_USER_SSL_KEY

# The destination database the data are copied to. Use either cockroach or postgres, by default cockroach is used
Destination:
  cockroach:
    Host: localhost # ZITADEL_DESTINATION_COCKROACH_HOST
    Port: 26257 # ZITADEL_DESTINATION_COCKROACH_PORT
    Database: zitadel # ZITADEL_DESTINATION_COCKROACH_DATABASE
    MaxOpenConns: 0 # ZITADEL_DESTINATION_COCKROACH_MAXOPENCONNS
    MaxIdleConns: 0 # ZITADEL_DESTINATION_COCKROACH_MAXIDLECONNS
    MaxConnLifetime: 30m # ZITADEL_DESTINATION_COCKROACH_MAXCONNLIFETIME
    MaxConnIdleTime: 5m # ZITADEL_DESTINATION_COCKROACH_MAXCONNIDLETIME
    EventPushConnRatio: 0.01 # ZITADEL_DESTINATION_COCKROACH_EVENTPUSHCONNRATIO
    ProjectionSpoolerConnRatio: 0.5 # ZITADEL_DESTINATION_COCKROACH_PROJECTIONSPOOLERCONNRATIO
    Options: "" # ZITADEL_DESTINATION_COCKROACH_OPTIONS
    User:
      Username: zitadel # ZITADEL_DESTINATION_COCKROACH_USER_USERNAME
      Password: "" # ZITADEL_DESTINATION_COCKROACH_USER_PASSWORD
      SSL:
        Mode: disable # ZITADEL_DESTINATION_COCKROACH_USER_SSL_MODE
        RootCert: "" # ZITADEL_DESTINATION_COCKROACH_USER_SSL_ROOTCERT
        Cert: "" # ZITADEL_DESTINATION_COCKROACH_USER_SSL_CERT
        Key: "" # ZITADEL_DESTINATION_COCKROACH_USER_SSL_KEY
  # Postgres is used as soon as a value is set
  # The values describe the possible fields to set values
  postgres:
    Host: # ZITADEL_DESTINATION_POSTGRES_HOST
    Port: # ZITADEL_DESTINATION_POSTGRES_PORT
    Database: # ZITADEL_DESTINATION_POSTGRES_DATABASE
    MaxOpenConns: # ZITADEL_DESTINATION_POSTGRES_MAXOPENCONNS
    MaxIdleConns: # ZITADEL_DESTINATION_POSTGRES_MAXIDLECONNS
    MaxConnLifetime: # ZITADEL_DESTINATION_POSTGRES_MAXCONNLIFETIME
    MaxConnIdleTime: # ZITADEL_DESTINATION_POSTGRES_MAXCONNIDLETIME
    Options: # ZITADEL_DESTINATION_POSTGRES_OPTIONS
    User:
      Username: # ZITADEL_DESTINATION_POSTGRES_USER_USERNAME
      Password: # ZITADEL_DESTINATION_POSTGRES_USER_PASSWORD
      SSL:
        Mode: # ZITADEL_DESTINATION_POSTGRES_USER_SSL_MODE
        RootCert: # ZITADEL_DESTINATION_POSTGRES_USER_SSL_ROOTCERT
        Cert: # ZITADEL_DESTINATION_POSTGRES_USER_SSL_CERT
        Key: # ZITADEL_DESTINATION_POSTGRES_USER_SSL_KEY

# As cockroachdb first copies the data into memory this parameter is used to iterate through the events table and fetch only the given amount of events per iteration
EventBulkSize: 10000 # ZITADEL_EVENTBULKSIZE

Projections:
  # Defines how many projections are allowed to run in parallel
  ConcurrentInstances: 7 # ZITADEL_PROJECTIONS_CONCURRENTINSTANCES
  # Limits the amount of events projected by each iteration
  EventBulkLimit: 1000 # ZITADEL_PROJECTIONS_EVENTBULKLIMIT

Auth:
  Spooler:
    # Limits the amount of events projected by each iteration
    BulkLimit: 1000 #ZITADEL_AUTH_SPOOLER_BULKLIMIT

Admin:
  Spooler:
    # Limits the amount of events projected by each iteration
    BulkLimit: 10 #ZITADEL_ADMIN_SPOOLER_BULKLIMIT

Log:
  Level: info
```

## Sub commands

The provided sub commands allow more fine grained execution of copying the data.

The following commands are safe to execute multiple times by adding the `--replace`-flag which replaces the data not provided by the events in the destination database.

### `zitadel mirror auth`

Copies the auth requests to the destination database.

### `zitadel mirror eventstore`

Copies the events since the last migration and unique constraints to the destination database.

### `zitadel mirror projections`

Executes all projections in the destination database.

It is NOOP if the projections are already up-to-date. 

### `zitadel mirror system`

Copies encryption keys and assets to the destination database.

### `zitadel mirror verify`

Prints the amount of rows of the source and destination database and the diff. Positive numbers indicate more rows in the destination table that in the source, negative numbers the opposite.

The following tables will likely have an unequal count:

* **projections.current_states**: If your deployment was upgraded several times, the number of entries in the destination will be lower
* **projections.locks**: If your deployment was upgraded several times, the number of entries in the destination will be lower
* **projections.keys4\***: Only not expired keys are inserted, the number of entries in the destination will be lower
* **projections.failed_events**: Should be lower or equal.
* **auth.users2**: Was replaced with auth.users3, the number of entries in the destination will be 0
* **auth.users3**: Is the replacement of auth.users2, the number of entries in the destination will be equal or higher

## Limitations

It is not possible to use files as source or destination. See github issue [here](https://github.com/zitadel/zitadel/issues/7966)

Currently the encryption keys of the source database must be copied to the destination database. See github issue [here](https://github.com/zitadel/zitadel/issues/7964)

It is not possible to change the domain of the ZITADEL deployment.

Once you mirrored an instance using the `--instance` flag, you have to make sure you don't mirror other preexisting instances. This means for example, you cannot mirror a few instances and then pass the `--system` flag. You have to pass all remaining instances explicitly, once you used the `--instance` flag