Falco Configuration Options

The location of the rules file(s). This can contain one or more paths to separate rules files. The following examples are equivalent:

rules_file:
- path1
- path2

rules_file: [path1, path2]

You can also specify multiple rules files on the command line via one or more -r options.

A list of objects. Each object has the following sub-keys:

• name: <string>
• library_path: <path>
• init_config: [<string>|<object>]
• open_params: <string>

Defines the set of plugins Falco can load.

name provides the plugin name. This is only used for load_plugins, but by convention should be the same as the value returned by the plugin_get_name() api function.

library_path is path to the shared library. The path can be relative, in which case it is relative to Falco's "share" directory under a "plugins" subdirectory e.g. /usr/share/falco/plugins.

If init_config is present, it contains the configuration that will be provided as an argument to the init() function. This can either be in string or object form. If a string is used, the plugin is configured with the string content as-is. If an object is used, by convention its contents are formatted into a JSON string and then passed to the plugin. In both cases, the configuration string is automatically parsed against a schema before being passed to the plugin if the get_init_schema function is implemented, otherwise it gets directly passed as an opaque string.

if open_params: is present, it contains the exact params string that will be provided as an argument to the open() function, which is used in plugins with event sourcing capability only.

A list of plugin names, corresponding to the name sub-key from the plugins config item. Example:

load_plugins: [cloudtrail, json]

List containing the following sub-keys:

• enabled: [true|false] (default is false)
• severity: One of fatal, critical, error, warning, notice, info, debug, trace.

List containing the following sub-keys:

• actions: A list containing one or more of these boolean sub-keys:
  • ignore: do nothing. If an empty list is provided, ignore is assumed.
  • log: log a CRITICAL message noting that the buffer was full.
  • alert: emit a Falco alert noting that the buffer was full.
  • exit: exit Falco with a non-zero rc.
• rate: The steady-state rate at which actions can be taken. Units of actions/second. Default 0.03333 (one action per 30 seconds).
• max_burst: The maximum number of actions that can be taken before the steady-state rate is applied.

List containing the following sub-keys:

• max_consecutives: maximum number of consecutive timeouts without an event after which you want Falco to alert. Default is 1000.

Integer between 1 and 10. Every value corresponds to a dimension in bytes:

(*), 1 MB, 2 MB, 4 MB, 8 MB, 16 MB,
 ^    ^     ^     ^     ^     ^    
 |    |     |     |     |     |    
 0    1     2     3     4     5    

32 MB, 64 MB, 128 MB, 256 MB, 512 MB
 ^      ^       ^       ^       ^
 |      |       |       |       |
 6      7       8       9       10

List containing the following sub-keys:

• rate: <notifications/second>
• max_burst: <number_of_messages>

A throttling mechanism implemented as a token bucket limits the rate of Falco notifications. One rate limiter is assigned to each one of the loaded event sources, so that alerts coming from one can't influence the throttling mechanism of the others. This throttling is controlled by the rate and max_burst options.

• rate: the number of tokens (i.e. right to send a notification) gained per second. When 0, the throttling mechanism is disabled. Defaults to 0.
• max_burst: the maximum number of tokens outstanding. Defaults to 1000.

Since Falco 0.33.0, this is optional and disabled by default with a rate of 0. For example, by setting rate to 1 Falco could send up to 1000 notifications after an initial quiet period, and then up to 1 notification per second afterward. It would gain the full burst back after 1000 seconds of no activity.

List containing the following sub-keys:

• enabled: [true|false]

List containing the following sub-keys:

• enabled: [true|false]
• keep_alive: [true|false]
• filename: <path>

If enabled is set to true, Falco alerts will be sent to the filepath specified in filename.

If keep_alive is set to false (the default), Falco will re-open the file for every alert. If true, Falco will open the file once and keep it open for all alerts. It may also be necessary to specify --unbuffered using the Falco CLI.

List containing the following sub-keys:

• enabled: [true|false]

List containing the following sub-keys:

• enabled: [true|false]
• keep_alive: [true|false]

If enabled is set to true, Falco alerts will be sent to a program.

If keep_alive is set to false (the default), run the program for each alert. If true, Falco will spawn the program once and keep it open for all alerts. It may also be necessary to specify --unbuffered using the Falco CLI.

The program setting specifies the program to be run for each alert. This is started via the shell, so you can specify a command pipeline to allow for additional formatting.

List containing the following sub-keys:

• enabled: [true|false]
• url: [http[s]://path/to/webhook/]

List containing the following sub-keys:

• enabled: [true|false]
• listen_port
• k8s_audit_endpoint
• ssl_enabled: [true|false]
• ssl_certificate: <path>
• threadiness: number

If enabled is set to true, Falco will start an embedded web server used to implement an health endpoint for checking if Falco is up and running

listen_port specifies the port on which the web server will listen. The default is 8765.

k8s_audit_endpoint specifies the URI on which to listen for Kubernetes audit events. The default is /k8s-audit.

ssl_enabled enables SSL support for the webserver, using the certificate specified in ssl_certificate. The specified ssl_certificate file should contain the server's certificate as well as the key.

threadiness enables configuring the number of threads used by the webserver (Default is 0). When 0, Falco automatically guesses it depending on the number of online cores

List containing the following sub-keys:

• enabled: [true|false]
• bind_address: [unix://<path>.sock|address:port]
• threadiness: <integer>
• private_key: <path>
• cert_chain: <path>
• root_certs: <path>

If enabled is set to true, Falco will embed a gRPC server to expose its gRPC API. The default is false.

Falco supports running a gRPC server with two main binding types:

• Over a local unix socket with no authentication
• Over the network with mandatory mutual TLS authentication (mTLS)

bind_address specifies either the unix socket path or the address and port on which the gRPC server will listen. The default is unix:///var/run/falco.sock.

threadiness defines the number of threads to use to serve gRPC requests. When threadiness is 0, Falco automatically guesses it depending on the number of online cores. The default is 0.

The gRPC server over the network can only be used with mutual authentication between the clients and the server using TLS certificates, and the following options should be provided:

private_key path of the private key for server authentication. The default is /etc/falco/certs/server.key.

cert_chain path of the public cert for server authentication. The default is /etc/falco/certs/server.crt.

root_certs path of the CA certificate (or chain) common between the server and all the clients. The default is /etc/falco/certs/ca.crt.

How to generate the certificates is documented here. Please always remember that the only common thing between server and clients is the root certificate. Every client will need to generate their own certificates signed by the same root CA as the server.

List containing the following sub-keys:

• enabled: [true|false]

List containing the following sub-keys:

• max_mb: number (Default: 100)
• chunk_wait_us: number (Default: 1000)
• watch_freq_sec: number (Default: 1)