---
layout: docs
page_title: What is Vault Proxy?
description: >-
  Vault Proxy is a server-side daemon with caching and auto-authentication that
  acts as load-balancer and API proxy for Vault.
---

# What is Vault Proxy?

Vault Proxy aims to remove the initial hurdle to adopt Vault by providing a
more scalable and simpler way for applications to integrate with Vault.
Vault Proxy acts as an [API proxy][apiproxy] for Vault, and can optionally allow
or force interacting clients to use its [automatically authenticated token][autoauth].

Vault Proxy is a client daemon that provides the following features:

- [Auto-auth][autoauth] - Automatically authenticate to Vault and manage the
token renewal process for locally-retrieved dynamic secrets.
- [API proxy][apiproxy] - Acts as a proxy for Vault's API,
optionally using (or forcing the use of) the auto-auth token.
- [Caching][caching] - Allows client-side caching of responses containing newly
created tokens and responses containing leased secrets generated off of these
newly created tokens. The agent also manages the renewals of the cached tokens and leases.

## Auto-auth

Vault Proxy allows easy authentication to Vault in a wide variety of
environments. Please see the [Auto-auth docs][autoauth]
for information.

Auto-auth functionality takes place within an `auto_auth` configuration stanza.

## API proxy

Vault Proxy's primary purpose is to act as an API proxy for Vault, allowing you to talk to Vault's
API via a listener. It can be configured to optionally allow or force the automatic use of
the auto-auth token for these requests. Please see  the [Use Vault Proxy as an API proxy][apiproxy] page
for more information.

API proxy functionality takes place within a defined `listener`, and its behaviour can be configured with an
[`api_proxy` stanza](/vault/docs/agent-and-proxy/proxy/apiproxy#configuration-api_proxy).

## Caching

Vault Proxy allows client-side caching of responses containing newly created tokens
and responses containing leased secrets generated off of these newly created tokens.
Please see the [Caching docs][caching] for information.

## API

### Quit

This endpoint triggers shutdown of the proxy. By default, it is disabled, and can
be enabled per listener using the [`proxy_api`][proxy-api] stanza. It is recommended
to only enable this on trusted interfaces, as it does not require any authorization to use.

| Method | Path             |
| :----- | :--------------- |
| `POST` | `/proxy/v1/quit` |

### Cache

See the [caching](/vault/docs/agent-and-proxy/proxy/caching#api) page for details on the cache API.

## Configuration

### Command options

- `-log-level` ((#\_log_level)) `(string: "info")` - Log verbosity level. Supported values (in
order of descending detail) are `trace`, `debug`, `info`, `warn`, and `error`. This can
also be specified via the `VAULT_LOG_LEVEL` environment variable.

- `-log-format` ((#\_log_format)) `(string: "standard")` - Log format. Supported values
are `standard` and `json`. This can also be specified via the
`VAULT_LOG_FORMAT` environment variable.

- `-log-file` ((#\_log_file)) - the absolute path where Vault Proxy should save
  log messages. Paths that end with a path separator use the default file name,
  `proxy.log`. Paths that do not end with a file extension use the default
  `.log` extension. If the log file rotates, Vault Proxy appends the current
  timestamp to the file name at the time of rotation. For example:

  `log-file` | Full log file | Rotated log file
  ---------- | ------------- | ----------------
  `/var/log` | `/var/log/proxy.log` | `/var/log/proxy-{timestamp}.log`
  `/var/log/my-diary` | `/var/log/my-diary.log` | `/var/log/my-diary-{timestamp}.log`
  `/var/log/my-diary.txt` | `/var/log/my-diary.txt` | `/var/log/my-diary-{timestamp}.txt`

- `-log-rotate-bytes` ((#\_log_rotate_bytes)) - to specify the number of
bytes that should be written to a log before it needs to be rotated. Unless specified,
there is no limit to the number of bytes that can be written to a log file.

- `-log-rotate-duration` ((#\_log_rotate_duration)) - to specify the maximum
duration a log should be written to before it needs to be rotated. Must be a duration
value such as 30s. Defaults to 24h.

- `-log-rotate-max-files` ((#\_log_rotate_max_files)) - to specify the maximum
number of older log file archives to keep. Defaults to `0` (no files are ever deleted).
Set to `-1` to discard old log files when a new one is created.

### Configuration file options

These are the currently-available general configuration options:

- `vault` <code>([vault][vault]: <optional\>)</code> - Specifies the remote Vault server the Proxy connects to.

- `auto_auth` <code>([auto_auth][autoauth]: <optional\>)</code> - Specifies the method and other options used for auto-auth functionality.

- `api_proxy` <code>([api_proxy][apiproxy]: <optional\>)</code> - Specifies options used for API proxy functionality.

- `cache` <code>([cache][caching]: <optional\>)</code> - Specifies options used for Caching functionality.

- `listener` <code>([listener][listener]: <optional\>)</code> - Specifies the addresses and ports on which the Proxy will respond to requests.

  <Highlight>

  On `SIGHUP` (`kill -SIGHUP $(pidof vault)`), Vault Proxy will attempt to reload listener TLS configuration.
  This method can be used to refresh certificates used by Vault Proxy without having to restart its process.

  </Highlight>

- `pid_file` `(string: "")` - Path to the file in which the Proxy's Process ID
(PID) should be stored

- `exit_after_auth` `(bool: false)` - If set to `true`, the proxy will exit
with code `0` after a single successful auth, where success means that a
token was retrieved and all sinks successfully wrote it

- `disable_idle_connections` `(string array: [])` - A list of strings that disables idle connections for various features in Vault Proxy.
Valid values include: `auto-auth`, and `proxying`. Can also be configured by setting the `VAULT_PROXY_DISABLE_IDLE_CONNECTIONS`
environment variable as a comma separated string. This environment variable will override any values found in a configuration file.

- `disable_keep_alives` `(string array: [])` - A list of strings that disables keep alives for various features in Vault Agent.
Valid values include: `auto-auth`, and `proxying`. Can also be configured by setting the `VAULT_PROXY_DISABLE_KEEP_ALIVES`
environment variable as a comma separated string. This environment variable will override any values found in a configuration file.

- `telemetry` <code>([telemetry][telemetry]: <optional\>)</code> – Specifies the telemetry
reporting system. See the [telemetry Stanza](/vault/docs/agent-and-proxy/proxy#telemetry-stanza) section below
for a list of metrics specific to Proxy.

- `log_level` - Equivalent to the [`-log-level` command-line flag](#_log_level).

  <Highlight>

  On `SIGHUP` (`kill -SIGHUP $(pidof vault)`), Vault Proxy will update the log level to the value
  specified by configuration file (including overriding values set using CLI or environment variable parameters).

  </Highlight>

- `log_format` - Equivalent to the [`-log-format` command-line flag](#_log_format).

- `log_file` - Equivalent to the [`-log-file` command-line flag](#_log_file).

- `log_rotate_duration` - Equivalent to the [`-log-rotate-duration` command-line flag](#_log_rotate_duration).

- `log_rotate_bytes` - Equivalent to the [`-log-rotate-bytes` command-line flag](#_log_rotate_bytes).

- `log_rotate_max_files` - Equivalent to the [`-log-rotate-max-files` command-line flag](#_log_rotate_max_files).

### vault stanza

There can at most be one top level `vault` block, and it has the following
configuration entries:

- `address` `(string: <optional>)` - The address of the Vault server to
connect to. This should be a Fully Qualified Domain Name (FQDN) or IP
such as `https://vault-fqdn:8200` or `https://172.16.9.8:8200`.
This value can be overridden by setting the `VAULT_ADDR` environment variable.

- `ca_cert` `(string: <optional>)` - Path on the local disk to a single PEM-encoded
CA certificate to verify the Vault server's SSL certificate. This value can
be overridden by setting the `VAULT_CACERT` environment variable.

- `ca_path` `(string: <optional>)` - Path on the local disk to a directory of
PEM-encoded CA certificates to verify the Vault server's SSL certificate.
This value can be overridden by setting the `VAULT_CAPATH` environment
variable.

- `client_cert` `(string: <optional>)` - Path on the local disk to a single
PEM-encoded CA certificate to use for TLS authentication to the Vault server.
This value can be overridden by setting the `VAULT_CLIENT_CERT` environment
variable.

- `client_key` `(string: <optional>)` - Path on the local disk to a single
PEM-encoded private key matching the client certificate from `client_cert`.
This value can be overridden by setting the `VAULT_CLIENT_KEY` environment
variable.

- `tls_skip_verify` `(string: <optional>)` - Disable verification of TLS
certificates. Using this option is highly discouraged as it decreases the
security of data transmissions to and from the Vault server. This value can
be overridden by setting the `VAULT_SKIP_VERIFY` environment variable.

- `tls_server_name` `(string: <optional>)` - Name to use as the SNI host when
connecting via TLS. This value can be overridden by setting the
`VAULT_TLS_SERVER_NAME` environment variable.

- `namespace` `(string: <optional>)` - Namespace to use for all of Vault Proxy's
requests to Vault. This can also be specified by command line or environment variable.
The order of precedence is: this setting lowest, followed by the environment variable
`VAULT_NAMESPACE`, and then the highest precedence command-line option `-namespace`.
If none of these are specified, defaults to the root namespace.

#### retry stanza

The `vault` stanza may contain a `retry` stanza that controls how failing Vault
requests are handled. Auto-auth, however, has its own notion of retrying and is not
affected by this section.

Here are the options for the `retry` stanza:

- `num_retries` `(int: 12)` - Specify how many times a failing request will
be retried. A value of `0` translates to the default, i.e. 12 retries.
A value of `-1` disables retries. The environment variable `VAULT_MAX_RETRIES`
overrides this setting.

Requests originating
from the proxy cache will only be retried if they resulted in specific HTTP
result codes: any 50x code except 501 ("not implemented"), as well as 412
("precondition failed"); 412 is used in Vault Enterprise 1.7+ to indicate a
stale read due to eventual consistency. Requests coming from the template
subsystem are retried regardless of the failure.

### listener stanza

Vault Proxy supports one or more [listener][listener_main] stanzas. Listeners
can be configured with or without [caching][caching], but will use the cache if it
has been configured, and will enable the [API proxy][apiproxy]. In addition to the standard
listener configuration, a Proxy's listener configuration also supports the following:

- `require_request_header` `(bool: false)` - Require that all incoming HTTP
requests on this listener must have an `X-Vault-Request: true` header entry.
Using this option offers an additional layer of protection from Server Side
Request Forgery attacks. Requests on the listener that do not have the proper
`X-Vault-Request` header will fail, with a HTTP response status code of `412: Precondition Failed`.

- `role` `(string: default)` - `role` determines which APIs the listener serves.
It can be configured to `metrics_only` to serve only metrics, or the default role, `default`,
which serves everything (including metrics). The `require_request_header` does not apply
to `metrics_only` listeners.

- `proxy_api` <code>([proxy_api][proxy-api]: <optional\>)</code> - Manages optional Proxy API endpoints.

#### proxy_api stanza

- `enable_quit` `(bool: false)` - If set to `true`, the Proxy will enable the [quit](/vault/docs/agent-and-proxy/proxy#quit) API.

### telemetry stanza

Vault Proxy supports the [telemetry][telemetry] stanza and collects various
runtime metrics about its performance, the auto-auth and the cache status:

| Metric                           | Description                                          | Type    |
| -------------------------------- | ---------------------------------------------------- | ------- |
| `vault.proxy.auth.failure`       | Number of authentication failures                    | counter |
| `vault.proxy.auth.success`       | Number of authentication successes                   | counter |
| `vault.proxy.proxy.success`      | Number of requests successfully proxied              | counter |
| `vault.proxy.proxy.client_error` | Number of requests for which Vault returned an error | counter |
| `vault.proxy.proxy.error`        | Number of requests the proxy failed to proxy         | counter |
| `vault.proxy.cache.hit`          | Number of cache hits                                 | counter |
| `vault.proxy.cache.miss`         | Number of cache misses                               | counter |

## Start Vault Proxy

To run Vault Proxy:

1. [Download](/vault/downloads) the Vault binary where the client application runs
(virtual machine, Kubernetes pod, etc.)

1. Create a Vault Proxy configuration file. (See the [Example
Configuration](#example-configuration) section for an example configuration.)

1. Start a Vault Proxy with the configuration file.

  **Example:**

  ```shell-session
  $ vault proxy -config=/etc/vault/proxy-config.hcl
  ```

  To get the command help, run:

  ```shell-session
  $ vault proxy -h
  ```

As with Vault, the `-config` flag can be used in three different ways:

- Use the flag once to name the path to a single specific configuration file.
- Use the flag multiple times to name multiple configuration files, which will be composed at runtime.
- Use the flag to name a directory of configuration files, the contents of which will be composed at runtime.

## Example configuration

An example configuration, with very contrived values, follows:

```hcl
pid_file = "./pidfile"

vault {
  address = "https://vault-fqdn:8200"
  retry {
    num_retries = 5
  }
}

auto_auth {
  method "aws" {
    mount_path = "auth/aws-subaccount"
    config = {
      type = "iam"
      role = "foobar"
    }
  }

  sink "file" {
    config = {
      path = "/tmp/file-foo"
    }
  }

  sink "file" {
    wrap_ttl = "5m"
    aad_env_var = "TEST_AAD_ENV"
    dh_type = "curve25519"
    dh_path = "/tmp/file-foo-dhpath2"
    config = {
      path = "/tmp/file-bar"
    }
  }
}

cache {
  // An empty cache stanza still enables caching
}

api_proxy {
  use_auto_auth_token = true
}

listener "unix" {
  address = "/path/to/socket"
  tls_disable = true

  agent_api {
    enable_quit = true
  }
}

listener "tcp" {
  address = "127.0.0.1:8100"
  tls_disable = true
}
```

[vault]: /vault/docs/agent-and-proxy/proxy#vault-stanza
[autoauth]: /vault/docs/agent-and-proxy/autoauth
[caching]: /vault/docs/agent-and-proxy/proxy/caching
[apiproxy]: /vault/docs/agent-and-proxy/proxy/apiproxy
[persistent-cache]: /vault/docs/agent-and-proxy/proxy/caching/persistent-caches
[proxy-api]: /vault/docs/agent-and-proxy/proxy/#proxy_api-stanza
[listener]: /vault/docs/agent-and-proxy/proxy#listener-stanza
[listener_main]: /vault/docs/configuration/listener/tcp
[telemetry]: /vault/docs/configuration/telemetry
