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Configuring an OpenTelemetry collector

As explained in What is OpenTelemetry and how is it used by Centreon Log Management?, you need to install an OpenTelemetry collector on your host to be able to send logs to CLM.

How is an OpenTelemetry Collector configured?​

An OpenTelemetry Collector has three main components that are executed one after the other:

  • Receivers read data from files or receive data from a stream. They accept logs in various formats and from various sources (e.g., OTLP, syslog, etc).
  • Processors let you filter, transform, or enrich data before it leaves the collector.
  • Exporters send the logs in OpenTelemetry format to Centreon Log Management.

How can I send logs to Centreon Log Management?​

Prerequisites​

CLM can process log batches up to 5 MiB in size. Beyond that, you will receive a 413 error. (If necessary, use the sending_queue.sizer.bytes parameter in your exporter to adjust the size of your batches.)

Step 1: Install OpenTelemetry Collector on your host​

Use the otelcol-contrib packages to install OpenTelemetry Collector on each device from which you want to collect logs.

wget https://github.com/open-telemetry/opentelemetry-collector-releases/releases/download/v0.139.0/otelcol-contrib_0.139.0_linux_amd64.rpm

Step 2: Define the global parameters of the collector​

  1. Edit the config.yaml file that was created when you installed the collector:

    You must be logged in as root.

    /etc/otelcol-contrib/config.yaml

  2. In this file, enter the global log collection settings specific to this device. These will apply to all log sources for this device.

    Example:

    # Copyright 2025 Centreon.
    # SPDX-License-Identifier: Apache-2.0
    exporters:
      otlphttp/centreon:
        endpoint: "https://api.euwest1.obs.mycentreon.com/v1/ingress/otlp/v1/logs"
        headers:
          "X-Api-Key": "<%TOKEN%>"
      debug:
        verbosity: detailed
    processors:
      batch:
      resourcedetection:
        detectors: ["system"]
        system:
          resource_attributes:
            host.name:
              enabled: true
            os.name:
              enabled: true
            os.type:
              enabled: true
            os.version:
              enabled: true

    The indentation of the parameters in your YAML file must be identical to that in the example. The indentations are two spaces for each level.

Step 3: Configure each log source for your host​

Configure a log source for each desired service (syslog, apache, etc.) in the form of a YAML file.

  1. Create the following directory:

    mkdir /etc/otelcol-contrib/conf.d/

  2. In this directory, create one file per log source. For example: the httpd-combined.yaml and httpd-error.yaml files will contain the configuration for the Apache access log and Apache error log, respectively.

  3. Retrieve from GitHub the sample file for the log source you want: https://github.com/CentreonLabs/centreon-otel-col-log-template/tree/main.

  4. On the source device, copy and paste the code snippet into the corresponding file. Save the file. If you are using several log sources for a collector, make sure you define the pipeline only once (in one of the files). The pipeline must mention all your receivers. In our example:

    service:
      pipelines:
        logs:
          receivers: [filelog/httpd-combined,filelog/apache-error]

    The indentation of the parameters in your YAML file must be identical to that in the example. The indentations are two spaces for each level.

  5. Declare each of the files you created: declare a --config option for each file, as in the following example (be sure to keep the declaration of the global configuration file config.yaml):

    In /etc/otelcol-contrib/otelcol-contrib.conf, add the following line (adapt it to your actual file names):

    OTELCOL_OPTIONS="--config=/etc/otelcol-contrib/config.yaml --config=/etc/otelcol-contrib/conf.d/httpd-combined.yaml --config=/etc/otelcol-contrib/conf.d/httpd-error.yaml"

  6. Restart the OpenTelemetry Collector service.

    systemctl restart otelcol-contrib.service

Troubleshooting​

Check the status of your collector on the host you want to receive logs from:

journalctl -u otelcol-contrib.service

If you do not receive expected logs in CLM, check that the otelcol-contrib user has sufficient rights to read the required files, according to the type of receiver. Example:

ls -l /var/log/messages
id otelcol-contrib
usermod -aG root otelcol-contrib