TLS / SSL

Fluent Bit provides integrated support for Transport Layer Security (TLS) and it predecessor Secure Sockets Layer (SSL) respectively. In this section we will refer as TLS only for both implementations.

Each output plugin that requires to perform Network I/O can optionally enable TLS and configure the behavior. The following table describes the properties available:

Property

Description

Default

tls

enable or disable TLS support

Off

tls.verify

force certificate validation

On

tls.debug

Set TLS debug verbosity level. It accept the following values: 0 (No debug), 1 (Error), 2 (State change), 3 (Informational) and 4 Verbose

1

tls.ca_file

absolute path to CA certificate file

tls.ca_path

absolute path to scan for certificate files

tls.crt_file

absolute path to Certificate file

tls.key_file

absolute path to private Key file

tls.key_passwd

optional password for tls.key_file file

tls.vhost

hostname to be used for TLS SNI extension

The listed properties can be enabled in the configuration file, specifically on each output plugin section or directly through the command line. The following output plugins can take advantage of the TLS feature:

Example: enable TLS on HTTP output

By default HTTP output plugin uses plain TCP, enabling TLS from the command line can be done with:

$ fluent-bit -i cpu -t cpu -o http://192.168.2.3:80/something \
-p tls=on \
-p tls.verify=off \
-m '*'

In the command line above, the two properties tls and tls.verify where enabled for demonstration purposes (we strongly suggest always keep verification ON).

The same behavior can be accomplished using a configuration file:

[INPUT]
Name cpu
Tag cpu
[OUTPUT]
Name http
Match *
Host 192.168.2.3
Port 80
URI /something
tls On
tls.verify Off

Tips and Tricks

Connect to virtual servers using TLS

Fluent Bit supports TLS server name indication. If you are serving multiple hostnames on a single IP address (a.k.a. virtual hosting), you can make use of tls.vhost to connect to a specific hostname.

[INPUT]
Name cpu
Tag cpu
[OUTPUT]
Name forward
Match *
Host 192.168.10.100
Port 24224
tls On
tls.verify On
tls.ca_file /etc/certs/fluent.crt
tls.vhost fluent.example.com