HAProxy load balancer discovery using probes

  • Release version: Zurich
  • Updated July 31, 2025
  • 2 minutes to read
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    Summary of HAProxy load balancer discovery using probes

    This process enables ServiceNow customers to discover HAProxy Community Edition load balancers using SSH-based probes. HAProxy is an open-source load balancer optimized for HTTP load balancing with session persistence and Layer 7 processing. Discovery focuses on HTTP load balancing; TCP load balancing is not supported. From Discovery and Service Mapping Patterns version 1.15.0 onward, pattern-based discovery is the default, but probe-based discovery can still be enabled as needed.

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    Key Requirements

    • HAProxy must be installed and running on a Linux server.
    • A ServiceNow MID Server must be deployed with access to the HAProxy server and its configuration file.
    • The discovery process locates the haproxy.cfg file either via the process output parameter or the default path /etc/haproxy/haproxy.cfg.
    • Discovery probes require valid credentials with privileges to execute commands on the target server.

    How Discovery Works

    • The Unix Active Processes probe looks for the HAProxy process named haproxy.
    • Upon identification, a record is created in the HAProxy Load Balancers [cmdbcilbhaproxy] table if it does not already exist.
    • Subsequent probes collect detailed information:
    Probe Description Commands Used
    HAProxy – Version Populates the HAProxy version in the HAProxy Load Balancers table. haproxy
    HAProxy – Get Configuration Populates additional HAProxy load balancer details and related CI tables:
    • Load Balancer Service
    • Load Balancer Pool
    • Load Balancer Pool Member
    • Load Balancer Interface
    • Load Balancer Application
    Also creates relationships among these CI records.     		echo, sed, cut, grep, egrep (via Borne shell script)

    Key Outcomes

    • Accurate identification and recording of HAProxy load balancers in the ServiceNow CMDB.
    • Detailed configuration data is captured and distributed across relevant CI tables, enabling comprehensive visibility into load balancer services, pools, members, interfaces, and applications.
    • Relationships among the discovered CIs are established to reflect real-world dependencies and associations, improving CMDB integrity and service mapping accuracy.

    Discovery of HAProxy Community edition load balancers is performed by SSH.

    Note:
    Starting with Discovery and Service Mapping Patterns 1.15.0 version, pattern-based discovery is the default method for discovering HAProxy load balancers.

    HAProxy is an open-source load balancer that can manage any TCP service. It is particularly suited for HTTP load balancing because it supports session persistence and Layer 7 processing. Discovery supports HAProxy for HTTP load balancing. TCP load-balancing is not supported.

    Consider the following requirements for discovering the HAProxy:
    • The HAProxy software is installed and running on a Linux server.
    • The MID Server is deployed to explore the server and the MID Server has access to the server HAProxy configuration file.
    • The configuration probe checks for the haproxy.cfg file using one of the following methods:
      • Using the f parameter for the HAProxy process output.
      • Using the default /etc/haproxy/haproxy.cfg path.
    • The HAProxy probes require credentials and execute privileges to run commands.

    Discovery uses the Unix - Active Processes probe to identify an HAProxy load balancer when the name of the process is haproxy. If this criterion matches, a record is created in the HAProxy Load Balancers [cmdb_ci_lb_haproxy] table if one does not already exist for that running process.

    The following probes are triggered after classification:
    Table 1. HAProxy probes
    Probe Description Commands
    HAProxy – Version The sensor of this probe populates the HAProxy version in the HAProxy Load Balancers [cmdb_ci_lb_haproxy] table. haproxy
    HAProxy – Get Configuration The sensor of this probe populates additional information in the HAProxy Load Balancers [cmdb_ci_lb_haproxy] table. The probe also populates information in the Load Balancer Service [cmdb_ci_lb_service], Load Balancer Pool [cmdb_ci_lb_pool], Load Balancer Pool Member [cmdb_ci_lb_pool_member], Load Balancer Interface [cmdb_ci_lb_interface], and Load Balancer Application [cmdb_ci_lb_appl] tables. echo, sed, cut, grep, egrep (within the Borne shell script)

    In addition to populating the data, the following relationships records are created in CI Relationships [cmdb_rel_ci] table:

    • The records in the cmdb_ci_lb_appl table run on the cmdb_ci_web_server table records.
    • The records in the cmdb_ci_lb_service table use the cmdb_ci_lb_pool table records.
    • The records in the cmdb_ci_pool table are used by the cmdb_ci_service table records.
    • The records in the cmdb_ci_pool table are members of the cmdb_ci_pool_member table records.
    • The records in the cmdb_ci_pool_member table are members of the cmdb_ci_pool table records.