# Environment Variables
URL: https://usememos.com/docs/configuration/environment-variables

Memos maps runtime flags to environment variables with the `MEMOS_` prefix. In production, environment variables are usually the cleanest way to keep deployment config explicit and repeatable.

## Reference [#reference]

All flags and their corresponding environment variables:

| Flag                                  | Environment variable                      | Default  | Purpose                                                               |
| ------------------------------------- | ----------------------------------------- | -------- | --------------------------------------------------------------------- |
| `--port`                              | `MEMOS_PORT`                              | `8081`   | HTTP listen port                                                      |
| `--addr`                              | `MEMOS_ADDR`                              | \`\`     | Bind address (empty = all interfaces)                                 |
| `--unix-sock`                         | `MEMOS_UNIX_SOCK`                         | \`\`     | Unix socket path                                                      |
| `--data`                              | `MEMOS_DATA`                              | auto     | Data directory                                                        |
| `--driver`                            | `MEMOS_DRIVER`                            | `sqlite` | Database backend (`sqlite`, `mysql`, `postgres`)                      |
| `--dsn`                               | `MEMOS_DSN`                               | auto     | Database connection string                                            |
| `--instance-url`                      | `MEMOS_INSTANCE_URL`                      | \`\`     | Canonical external URL; independent of access policy                  |
| `--demo`                              | `MEMOS_DEMO`                              | `false`  | Demo mode                                                             |
| `--webhook-private-network-allowlist` | `MEMOS_WEBHOOK_PRIVATE_NETWORK_ALLOWLIST` | empty    | Allowed private destinations: exact hostnames, IP addresses, or CIDRs |
| `--allow-private-webhooks`            | `MEMOS_ALLOW_PRIVATE_WEBHOOKS`            | `false`  | Deprecated blanket exception for private webhook destinations         |
| `--log-level`                         | `MEMOS_LOG_LEVEL`                         | `info`   | Log verbosity (`debug`, `info`, `warn`, `error`)                      |

### Data directory defaults [#data-directory-defaults]

`MEMOS_DATA` resolves automatically when not set:

* **Windows**: `%ProgramData%\memos`
* **Docker**: `/var/opt/memos` (when writable)
* **Linux / macOS**: current directory (`.`)

### DSN defaults [#dsn-defaults]

When `MEMOS_DRIVER=sqlite` and `MEMOS_DSN` is empty, the database file defaults to `{MEMOS_DATA}/memos_prod.db`. For MySQL and PostgreSQL, `MEMOS_DSN` is required.

### Public and private mode [#public-and-private-mode]

In Memos 0.31, access is controlled by the `ACCESS` instance setting, through `accessSetting.accessMode`:

* `INSTANCE_ACCESS_MODE_PRIVATE`: anonymous visitors are sent to sign-in; anonymous API access is limited to endpoints such as setup, authentication, registration when allowed, and explicit shared memos.
* `INSTANCE_ACCESS_MODE_PUBLIC`: eligible public memos, profiles, and Explore can be read anonymously.

Configure access in instance settings or with a [deployment-managed JSON file](/docs/configuration/deployment-configuration#access-policy). It is not a runtime flag or environment variable.

`MEMOS_INSTANCE_URL` supplies the canonical external address, including for a private instance behind a proxy. It must be an absolute HTTP(S) URL without credentials, a query, or a fragment, such as `https://memos.example.com`.

When the access setting is first initialized, Memos preserves the earlier behavior: a configured URL initializes public access; an empty URL initializes private access. Once the setting exists, changing the URL never changes the access policy. See [Upgrading to 0.31](/docs/operations/upgrade#upgrading-to-031).

## Priority order [#priority-order]

1. Command-line flags (highest)
2. Environment variables
3. Default values (lowest)

An explicit flag always wins over the environment variable for the same setting.

## Practical guidance [#practical-guidance]

* select private or public access explicitly in the `ACCESS` instance setting
* set `MEMOS_INSTANCE_URL` to the canonical external URL when the app sits behind a proxy
* prefer explicit `MEMOS_DRIVER` and `MEMOS_DSN` when you are not using SQLite defaults
* allow only required private webhook destinations with `MEMOS_WEBHOOK_PRIVATE_NETWORK_ALLOWLIST`; leave the deprecated blanket option disabled
* keep secrets such as database credentials outside committed compose files
* treat these values as part of deployment config and back them up accordingly

## Common patterns [#common-patterns]

SQLite with explicit data directory:

```bash
export MEMOS_DRIVER=sqlite
export MEMOS_DATA=/var/opt/memos
./memos
```

External PostgreSQL:

```bash
export MEMOS_DRIVER=postgres
export MEMOS_DSN="postgres://user:password@db:5432/memos?sslmode=disable"
export MEMOS_INSTANCE_URL=https://memos.example.com
./memos
```

Unix socket with Nginx (useful for local reverse proxy):

```bash
export MEMOS_UNIX_SOCK=/var/run/memos.sock
export MEMOS_DATA=/var/lib/memos
export MEMOS_INSTANCE_URL=https://memos.example.com
./memos
```

Nginx upstream for the socket:

```nginx
upstream memos {
    server unix:/var/run/memos.sock;
}
```