forward
Last updated
Last updated
The in_forward Input plugin listens to a TCP socket to receive the event stream. It also listens to a UDP socket to receive heartbeat messages. See also the protocol section for implementation details.
This plugin is mainly used to receive event logs from other Fluentd instances, the fluent-cat command, or Fluentd client libraries. This is by far the most efficient way to retrieve the records.
If you want to receive events from raw TCP payload, use in_tcp plugin instead.
It is included in Fluentd's core.
Refer to the Configuration File article for the basic structure and syntax of the configuration file.
@typeThe value must be forward.
portinteger
24224
0.14.0
The port to listen to.
bindstring
0.0.0.0 (all addresses)
0.14.0
The bind address to listen to.
tagstring
nil
1.5.0
in_forward uses incoming event's tag by default (See Protocol Section). If the tag parameter is set, its value is used instead.
add_tag_prefixstring
nil
1.5.0
Adds the prefix to the incoming event's tag.
Here is an example:
With this configuration, the emitted tag is prod.INCOMING_TAG, e.g. prod.app.log.
linger_timeoutinteger
0
0.14.0
The timeout used to set the linger option.
This parameter is deprecated since v1.14.6. Use <transport> directive instead.
resolve_hostnamebool
false
0.14.10
Tries to resolve hostname from IP addresses or not.
deny_keepalivebool
false
0.14.5
The connections will be disconnected right after receiving a message, if true.
send_keepalive_packetbool
false
1.4.2
Enables the TCP keepalive for sockets. See socket article for more details.
chunk_size_limitsize
nil (no limit)
0.14.0
The size limit of the received chunk. If the chunk size is larger than this value, the received chunk is dropped.
chunk_size_warn_limitsize
nil (no warning)
0.14.0
The warning size limit of the received chunk. If the chunk size is larger than this value, a warning message will be sent.
skip_invalid_eventbool
false
0.14.0
Skips the invalid incoming event.
This option is useful for forwarder, not aggregator.
source_address_keystring
nil (no adding address)
0.14.11
The field name of the client's source address. If set, the client's address will be set to its key.
source_hostname_keystring
nil (no adding hostname)
0.14.4
The field name of the client's hostname. If set, the client's hostname will be set to its key.
This iterates incoming events. So, if you send larger chunks to in_forward, it needs additional processing time.
<transport> SectionThis section is for setting TLS transport or some general transport configurations.
linger_timeout
integer
0
tcp, tls
1.14.6
The timeout (seconds) to set SO_LINGER.
The default value 0 is to send RST rather than FIN to avoid lots of connections sitting in TIME_WAIT on closing on non-Windows.
You can set positive value to send FIN on closing on non-Windows.
On Windows, Fluentd sends FIN without depending on this setting.
See How to Enable TLS Encryption section for how to use and see Configuration Example for all supported parameters.
Without <transport tls>, in_forward uses raw TCP.
<security> Sectionfalse
false
0.14.5
This section contains parameters related to authentication:
self_hostname
shared_key
user_auth
allow_anonymous_source
self_hostnamestring
required parameter
0.14.5
The hostname.
shared_keystring
required parameter
0.14.5
The shared key for authentication.
user_authbool
false
0.14.5
If true, user-based authentication is used.
allow_anonymous_sourcebool
true
0.14.5
Allows the anonymous source. <client> sections are required, if disabled.
<user> sectionfalse
true
0.14.5
This section contains user-based authentication:
username
password
This section can be used in <security>.
username
string
required parameter
0.14.5
The username for authentication.
password
string
required parameter
0.14.5
The password for authentication.
<client> sectionfalse
true
0.14.5
This section contains client IP/Network authentication and shared key per host:
host
network
shared_key
users
This section can be used in <security>
host
string
nil
0.14.5
The IP address or hostname of the client.
This is exclusive with network.
network
string
nil
0.14.5
The network address specification.
This is exclusive with host.
shared_key
string
nil
0.14.5
The shared key per client.
users
array
[]
0.14.5
The array of usernames.
This plugin accepts both JSON or MessagePack messages and automatically detects which one is used. Internally, Fluentd uses MessagePack as it is more efficient than JSON.
The time value is an EventTime or a platform-specific integer and is based on the output of Ruby's Time.now.to_i function. On Linux, BSD, and Mac systems, this is the number of seconds since 1970.
Multiple messages may be sent on the same connection:
For more details, see Fluentd Forward Protocol Specification (v1).
Since v0.14.12, Fluentd includes a built-in TLS support. Here we present a quick tutorial for setting up TLS encryption:
First, generate a self-signed certificate using the following command:
Move the generated certificate and private key to a safer place. For example:
Then, add the following settings to td-agent.conf and restart the service:
To test your encryption settings, execute the following command in your terminal. If the encryption is working properly, you should see a line containing {"foo":"bar"} in the log file:
If you can confirm TLS encryption has been set up correctly, please proceed to the configuration of the out_forward server.
Since v1.1.1, Fluentd supports TLS mutual authentication (i.e. client certificate auth). If you want to use this feature, please set the client_cert_auth and ca_path options like this:
When this feature is enabled, Fluentd will check all the incoming requests for a client certificate signed by the trusted CA. Requests with an invalid client certificate will fail.
To check if mutual authentication is working properly, issue the following command:
If the connection gets established successfully, your setup is working fine.
+For fluentd and fluent-bit combination, see Banzai Cloud article: Secure logging on Kubernetes with Fluentd and Fluent Bit.
Fluentd is equipped with a password-based authentication mechanism, which allows you to verify the identity of each client using a shared secret key.
To enable this feature, you need to add a <security> section to your configuration file like this:
Once the setup is complete, you have to configure your clients accordingly. For example, if you have an out_forward instance running on another server, configure it by following these instructions.
If you use this plugin under the multi-process environment, the port will be shared.
With this configuration, the three (3) workers share the port 24224. No need for an additional port. Incoming data will be routed to the workers automatically.
in_forward does not provide parsing mechanism unlike in_tail or in_tcp because in_forward is mainly for efficient log transfer. If you want to parse an incoming event, use parser filter in your pipeline.
See Docker Logging driver use case.
If this article is incorrect or outdated, or omits critical information, please let us know. Fluentd is an open-source project under Cloud Native Computing Foundation (CNCF). All components are available under the Apache 2 License.
