How can I override the configuration file?

Velociraptor relies on the configuration file to control the operation of the server or client. Usually the configuration file is generated interactively using the velociraptor config generate -i command.

Many people want to automate the configuration generation or override the configuration in some way. This short tip covers some of the common ways to do that.

Automating configuration generation.

When generating a new configuration, Velociraptor will generate new key material and create a reasonable skeleton for the supported deployment scenario. In the following command, Velociraptor will emit a basic configuration file template to standard output, which can be easily redirected to a file:

$ velociraptor-v0.6.4-linux-amd64 config generate > /tmp/config.yaml

To customize the generated configuration we can apply a JSON merge/patch step. JSON merge and JSON patch are standard ways of specifying a transformation on a JSON object.

Normally the configuration file is in YAML but you can also view it in JSON using the --json flag to the config show command:

velociraptor --config config.yaml config show --json

Since YAML is a superset of JSON you can also provide this JSON blob to Velociraptor as the actual configuration (no need to convert it back to YAML). This helps to prepare the JSON merge patch - simply remove the fields you dont want to change and change the fields you do want to change.

For example, imagine we want to specify a new URL for clients to connect to. We can merge the following JSON blob with the config:

$ velociraptor --config /tmp/config.yaml config show --merge '{"Client":{"server_urls":["", ""]}}' > /tmp/new_config.yaml

It may be more convenient to store the JSON merge blob in a file instead of specifying on the command line - use the --merge_file option to provide it.

Overriding configuration at runtime

While the config show command can be used to manipulate the configuration file, sometimes we want to change a few values at runtime on a temporary basis.

The first option is using the --config_override flag to specify the path to a JSON merge file that overrides the configuration at runtime. Velociraptor will load the configuration file specified by the --config flag as normal, but then will apply the JSON merge blob to override specific fields.

This is useful for specifying a larger configuration manipulation - it will not change the main config file at all, but will change the running configuration

Overriding configuration via command line flags

Velociraptor allows most configuration settings to be overriden by suitable command line flags. Since there are so many flags, the usual help shown with the --help flag does not include these configuration overriding flags.

You can see all the defined flags by enabling the DEBUG environment variable:

$ DEBUG=1 ./velociraptor --help


This is useful to override specific settings temporarily - for example when running the server in a cloud environment, the bind port is determined by the platform. In this case it is easier to simply override this on the command line rather than manipulate the config file.

velociraptor --config /etc/velociraptor/server.config.yaml frontend --config.frontend-bind-port=$PORT