Vault Agent Windows service

Vault Agent can be run as a Windows service. In order to do this, you need to register Vault Agent with the Windows Service Control Manager. After Vault Agent is registered, it can be started like any other Windows service.

While this guide focuses on an example for Vault Agent, this example can be easily adapted to work for Vault Proxy by changing the config and subcommand given to vault.exe as appropriate.

Note: These commands should be run in a PowerShell session with Administrator capabilities.

Register Vault Agent as a Windows service

There are multiple ways to register Vault Agent as a Windows service. One way is to use sc.exe. sc.exe works best if the path to your Vault binary and its associated agent config file do not contain spaces. sc.exe can be pretty tricky to get working correctly if your path contains spaces, as paths containing spaces must be quoted, and escaping quotes correctly in a way that makes sc.exe happy is non-trivial. If your path contains spaces, or you prefer not to use sc.exe, another alternative is to use the New-Service cmdlet. New-Service is less picky about the method used to escape quotes, and can sometimes be easier. Examples of both will be shown below.

Using sc.exe

Important Note: Ensure the executable path of the service is quoted, especially when it contains spaces, to avoid potential privilege escalation risks.

If you use sc.exe, make sure you specify sc.exe explicitly, and not just sc. The command below shows the creation of Vault Agent as a service, using "Vault Agent" as the display name, and starting automatically when Windows starts. The binPath argument should include the fully qualified path to the Vault executable, as well as any arguments required.

PS C:\Windows\system32> sc.exe create VaultAgent binPath="C:\vault\vault.exe agent -config=C:\vault\agent-config.hcl" displayName="Vault Agent" start=auto
[SC] CreateService SUCCESS

Note that the spacing after the = in all of the arguments is intentional and required.

If you receive a success message, your service is registered with the service manager.

If you get an error, please verify the path to the binary and check the arguments, by running the contents of binPath= directly in a PowerShell session and observing the results.

Using New-Service

The syntax is slightly different for New-Service, but the gist is the same. The invocation below is equivalent to the sc.exe one above.

PS C:\Windows\system32> New-Service -Name "VaultAgent" -BinaryPathName "C:\vault\vault.exe agent -config=C:\vault\agent-config.hcl" -DisplayName "Vault Agent" -StartupType "Automatic"

Status   Name               DisplayName
------   ----               -----------
Stopped  VaultAgent         Vault Agent

As mentioned previously, New-Service is easier to use if the path to your Vault executable and/or agent config contains spaces. Below is an example of how to configure Vault Agent as a service using a path with spaces.

PS C:\Windows\system32> New-Service -Name "VaultAgent" -BinaryPathName '"C:\my dir\vault.exe" agent -config="C:\my dir\agent-config.hcl"' -DisplayName "Vault Agent" -StartupType "Automatic"

Status   Name               DisplayName
------   ----               -----------
Stopped  VaultAgent         Vault Agent

Note that only the paths themselves are double quoted, and the entire BinaryPathName is wrapped in single quotes, in order to escape the double quotes used for the paths.

If anything goes wrong during this process, and you need to manually edit the path later, use the Registry Editor to find the following key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VaultAgent. You can edit the ImagePath value at that key to the correct path.

Start the Vault Agent service

There are multiple ways to start the service.

Using the sc.exe command.
Using the Start-Service cmdlet.
Go to the Windows Service Manager, and look for VaultAgent in the service name column. Click the Start button to start the service.

Example starting Vault Agent using `sc.exe`

PS C:\Windows\system32> sc.exe start VaultAgent

SERVICE_NAME: VaultAgent
     TYPE               : 10  WIN32_OWN_PROCESS
     STATE              : 4  RUNNING
                             (STOPPABLE, NOT_PAUSABLE, ACCEPTS_SHUTDOWN)
     WIN32_EXIT_CODE    : 0  (0x0)
     SERVICE_EXIT_CODE  : 0  (0x0)
     CHECKPOINT         : 0x0
     WAIT_HINT          : 0x0
     PID                : 6548
     FLAGS              :

Example starting Vault Agent using `Start-Service`

PS C:\Windows\system32> Start-Service -Name "VaultAgent"

Note that in the case where the service was started successfully, New-Service does not return any output.