Secret files guideedit

This guide provides step-by-step examples with best practices on how to deploy secret files directly on a host or through the Kubernetes secrets engine.

Secrets on filesystemedit

Secret files can be provisioned as plain text files directly on filesystems and referenced or passed through Elastic Agent.

We recommend these steps to improve security.

File permissionsedit

File permissions should not allow for global read permissions.

On MacOS and Linux, you can set file ownership and file permissions with the chown and chmod commands, respectively. Fleet Server runs as the root user on MacOS and Linux, so given a file named mySecret, you can alter it with:

sudo chown root:root mySecret # set the user:group to root
sudo chmod 0600 mySecret      # set only the read/write permission flags for the user, clear group and global permissions.

On Windows, you can use icacls to alter the ACL list associated with the file:

Write-Output -NoNewline SECRET > mySecret          # Create the file mySecret with the contents SECRET
icacls .\mySecret /inheritance:d                   # Remove inherited permissions from file
icacls .\mySecret /remove:g BUILTIN\Administrators # Remove Administrators group permissions
icacls .\mySecret /remove:g $env:UserName          # Remove current user's permissions
Temporary filesystemedit

You can use a temporary filesystem (in RAM) to hold secret files in order to improve security. These types of filesystems are normally not included in backups and are cleared if the host is reset. If used, the filesystem and secret files need to be reprovisioned with every reset.

On Linux you can use mount with the tmpfs filesystem to create a temporary filesystem in RAM:

mount -o size=1G -t tmpfs none /mnt/fleet-server-secrets

On MacOS you can use a combination of diskutil and hdiutil to create a RAM disk:

diskutil erasevolume HFS+ 'RAM Disk' `hdiutil attach -nobrowse -nomount ram://2097152`

Windows systems do not offer built-in options to create a RAM disk, but several third party programs are available.


Here is a step by step guide for provisioning a service token on a Linux system:

sudo mkdir -p /mnt/fleet-server-secrets
sudo mount -o size=1G -t tmpfs none /mnt/fleet-server-secrets
echo -n MY-SERVICE-TOKEN > /mnt/fleet-server-secrets/service-token
sudo chown root:root /mnt/fleet-server-secrets/service-token
sudo chmod 0600 /mnt/fleet-server-secrets/service-token

The -n flag is used with echo to prevent a newline character from being appended at the end of the secret. Be sure that the secret file does not contain the trailing newline character.

Secrets in containersedit

When you are using secret files directly in containers without using Kubernetes or another secrets management solution, you can pass the files into containers by mounting the file or directory. Provision the file in the same manner as it is in Secrets on filesystem and mount it in read-only mode. For example, when using Docker.

If you are using Elastic Agent image:

docker run \
	-v /path/to/creds:/creds:ro \
        -e FLEET_SERVER_CERT_KEY_PASSPHRASE=/creds/passphrase \
        -e FLEET_SERVER_SERVICE_TOKEN_PATH=/creds/service-token \

Secrets in Kubernetesedit

Kubernetes has a secrets management engine that can be used to provision secret files to pods.

For example, you can create the passphrase secret with:

kubectl create secret generic fleet-server-key-passphrase \

And create the service token secret with:

kubectl create secret generic fleet-server-service-token \

Then include it in the pod specification, for example, when you are running Fleet Server under Elastic Agent:

  - name: key-passphrase
      secretName: fleet-server-key-passphrase
  - name: service-token
      secretName: fleet-server-service-token
  - name: fleet-server
    - name: key-passphrase
      mountPath: /var/secrets/passphrase
    - name: service-token
      mountPath: /var/secrets/service-token
      value: /var/secrets/passphrase/value
      value: /var/secrets/service-token/value
Elastic Agent Kubernetes secrets provideredit

When you are running Fleet Server under Elastic Agent in Kubernetes, you can use Elastic Agent’s Kubernetes Secrets Provider to insert a Kubernetes secret directly into Fleet Server’s configuration. Note that due to how Fleet Server is bootstrapped only the APM secrets (API key or secret token) can be specified with this provider.