Overview

On a Linux host or VM, use Single Step Instrumentation (SSI) for APM to install the Datadog Agent and instrument your applications in one step, with no additional configuration required.

npx skills add https://github.com/datadog-labs/agent-skills --skill dd-apm --full-depth -y

Enable APM on your applications

New Agent installation

If you don’t yet have a Datadog Agent installed, install the Agent and enable SSI in one step.

1. Run the following command on your Linux host or VM:

   DD_API_KEY=<YOUR_DD_API_KEY> \
   DD_SITE="" \
   DD_APM_INSTRUMENTATION_ENABLED=host \
   bash -c "$(curl -L https://install.datadoghq.com/scripts/install_script_agent7.sh)"
   

   Replace <YOUR_DD_API_KEY> with your Datadog API key. The command installs or updates the Agent and the SSI packages.

   By default, SSI installs the latest SDK versions. To pin specific versions, add the DD_APM_INSTRUMENTATION_LIBRARIES variable with comma-separated language:major pairs. Available versions are listed in the source repositories for each language: Java (java), Node.js (js), Python (python), .NET (dotnet), Ruby (ruby), PHP (php).

2. Restart your applications.

Generate the command from Datadog

To get a command pre-filled with your API key and site, go to the Install the Datadog Agent on Linux page and turn on Application Performance Monitoring under Core Observability.

To select SDK versions from dropdowns, click Customize Library Versions.

Then copy and run the generated command.

Existing Agent installation

If you already have a Datadog Agent installed, re-run the Agent installation command from New Agent installation on the host. The command updates the existing Agent and enables SSI.

Alternatively, use Fleet Automation to enable SSI from Datadog:

1. In Datadog, go to Fleet Automation > Configuration.

2. Click Configure Agents.

3. Apply filters to select the agents you want to configure, then click Next.

4. Click the Application Performance Monitoring (APM) tile, then click Next.

5. In the Configure SDKs Installation screen, click Yes to automatically install the SDKs. Select Use latest version, or uncheck to specify individual SDK versions.

6. Click Next.

7. Review your configuration and click Deploy Configuration.

Verify the installation

1. Confirm the Agent is running:

   sudo datadog-agent status
   

2. Confirm that SSI injection is armed on the host:

   cat /etc/ld.so.preload && ls /opt/datadog-packages/ | grep apm
   

   The output lists the APM injector library in /etc/ld.so.preload and one or more datadog-apm-* packages.

3. After your applications receive traffic, confirm your services appear on the APM Services page. If they don’t appear within a few minutes, follow the SSI troubleshooting guide.

Configure Unified Service Tags

Unified Service Tags (USTs) apply consistent tags across traces, metrics, and logs, making it easier to navigate and correlate your observability data. Learn how to set USTs for Linux services.

Enable SDK-dependent products and features

After SSI loads the Datadog SDK into your applications and enables distributed tracing, you can configure additional products that rely on the SDK:

Note: All variables accept true or false. DD_PROFILING_ENABLED also accepts auto, which profiles only eligible processes and is recommended for SSI.

Use one of the following setup methods:

• Configure in application_monitoring.yaml:

  Configure products and features across all services on a host without modifying application command lines.

• Set environment variables:

  Enable products by setting environment variables directly in your application configuration.

Advanced options

Update SDK version

The SDK version is fixed when you run the Agent installation command.

To update the SDK versions:

1. Re-run the Agent installation command. This command also updates the Agent to the latest version.
2. Restart your applications.

Define instrumentation rules

Instrumentation rules (available for Agent v7.73+) let you control which processes are automatically instrumented by SSI on Linux hosts.

To configure instrumentation rules:

1. In Datadog, go to APM > Service Setup > Manage Instrumentation Rules.

2. Click Add or Edit Rules.

3. Define instrumentation rules:

   1. Click Add New Rule, then choose Allow Rule or Block Rule to specify whether matching processes should be instrumented.
   2. Name your rule.
   3. Add one or more conditions. See Define rule conditions to learn more.

4. (Optional) Drag and drop rules to reorder them.

   Note: Rules are evaluated in order. After a process matches a rule, subsequent rules are ignored.

5. Set the default behavior (allow or block) for processes that do not match any rule.

6. Click Next to preview your rules.

7. Click Deploy Rules.

If Remote Configuration is enabled, rules are deployed to every host and applied on those with SSI enabled within 50 seconds. Alternatively, click Export to export the configuration file and apply it manually to your hosts.

Define rule conditions

Each rule consists of one or more conditions. A condition includes the following elements:

• Attribute: The process property that the rule evaluates.
• Operator: The comparison logic (equals, not equals, prefix, or contains).
• Value: The text or pattern to match, such as a process name or command-line flag.

Supported attributes include:

Example use cases

Review the following examples demonstrating how to apply instrumentation rules:

Example 1: Instrument all processes except specific ones

Instrument all processes by default. Add block rules to exclude services that would add noise without value, such as analytics cron jobs and Java batch processors.

Example 2: Instrument only specific processes

Block all instrumentation by default. Add allow rules to opt specific processes into APM. This approach gives you precise control and works well for gradual rollouts. For example, to instrument only a checkout service and a customer portal, create allow rules using Working Directory, then set the default behavior to Block Instrumentation.

Remove Single Step APM instrumentation from your Agent

To stop producing traces for all services on your infrastructure:

1. Run:

   dd-host-install --uninstall
   

2. Restart the services on the host or VM.

Troubleshooting

If you encounter problems enabling APM with SSI, see the SSI troubleshooting guide.

Further reading

Documentation, liens et articles supplémentaires utiles:

Enable Runtime MetricsDOCUMENTATION Manage service tracing across hosts with Single Step Instrumentation rulesBLOG