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Collect logs for the Collector for Linux 🔗

Use the Universal Forwarder to send logs to the Splunk platform. See more at Use the Splunk Universal Forwarder with the Collector.

Fluentd is turned off by default. If you already installed Fluentd on a host, re-install the Collector without Fluentd using the --without-fluentd option.

Collect Linux logs with Fluentd 🔗

If you want to collect logs for the target host with Fluentd, use the --with-fluentd option to also install Fluentd when installing the Collector. For example:

curl -sSL https://dl.signalfx.com/splunk-otel-collector.sh > /tmp/splunk-otel-collector.sh && \
sudo sh /tmp/splunk-otel-collector.sh --with-fluentd --realm $SPLUNK_REALM -- $SPLUNK_ACCESS_TOKEN

When turned on, the Fluentd service is configured by default to collect and forward log events with the @SPLUNK label to the Collector, which then sends these events to the HEC ingest endpoint determined by the --realm <SPLUNK_REALM> option. For example, https://ingest.<SPLUNK_REALM>.signalfx.com/v1/log.

The following Fluentd plugins are also installed:

  • capng_c for activating Linux capabilities.

  • fluent-plugin-systemd for systemd journal log collection.

Additionally, the following dependencies are installed as prerequisites for the Fluentd plugins:

  • build-essential

  • libcap-ng0

  • libcap-ng-dev

  • pkg-config

You can specify the following parameters to configure the package to send log events to a custom Splunk HTTP Event Collector (HEC) endpoint URL:

  • --hec-url <URL>

  • --hec-token <TOKEN>

HEC lets you send data and application events to a Splunk deployment over the HTTP and Secure HTTP (HTTPS) protocols. See Set up and use HTTP Event Collector in Splunk Web .

The main Fluentd configuration is installed to /etc/otel/collector/fluentd/fluent.conf. Custom Fluentd source configuration files can be added to the /etc/otel/collector/fluentd/conf.d directory after installation.

Note the following:

  • In this directory, all files with the .conf extension are automatically included by Fluentd.

  • The td-agent user must have permissions to access the configuration files and the paths defined within.

  • By default, Fluentd is configured to collect systemd journal log events from /var/log/journal.

After any configuration modification, run sudo systemctl restart td-agent to restart the td-agent service.

If the td-agent package is upgraded after initial installation, you might need to set the Linux capabilities for the new version by performing the following steps for td-agent versions 4.1 or higher:

  1. Check for the activated capabilities:

    sudo /opt/td-agent/bin/fluent-cap-ctl --get -f /opt/td-agent/bin/ruby
Capabilities in `` /opt/td-agent/bin/ruby`` ,
Effective:   dac_override, dac_read_search
Inheritable: dac_override, dac_read_search
Permitted:   dac_override, dac_read_search

  2. If the output from the previous command does not include dac_override and dac_read_search as shown above, run the following commands:

    sudo td-agent-gem install capng_c
sudo /opt/td-agent/bin/fluent-cap-ctl --add "dac_override,dac_read_search" -f /opt/td-agent/bin/ruby
sudo systemctl daemon-reload
sudo systemctl restart td-agent

This page was last updated on Oct 09, 2024.