Preload

A system module that hooks into the operating system's execve function to automatically load APM (Application Performance Monitoring) agents.

Key Features:

• Automatically detects the programming language of target applications
• Injects necessary environment variables based on the detected language-specific APM agent
• Auto-generates ServiceName (currently Java only)
• Maintains seamless program execution flow

Installation

• Run make dist to create installation files, then execute bash install.sh for local installation
• Run make release to create install-apo-instrument.tar.gz package for deployment on other machines

Uninstallation

Remove the following line from /etc/ld.so.preload:

/etc/apo/instrument/libapolanucher.so

If this is the only line in the file, you can safely remove the entire /etc/ld.so.preload file. Restart your terminal session to complete the uninstallation.

Troubleshooting

If SSH access becomes unavailable due to preload issues, you can fix it by either:

• Using scp to copy an empty file to overwrite /etc/ld.so.preload on the target machine
• Completing the uninstallation process

To clean up remaining files afterward:

rm -r /etc/apo

Usage in Virtual Machines

The preload hook takes effect for all program executions immediately after running install.sh.

Usage in Docker Containers

After installing on the host machine, add these parameters when starting containers:

-v /etc/apo:/etc/apo
-e LD_PRELOAD=/etc/apo/instrument/libapolanucher.so

The -v flag mounts the agent files, while -e enables the preload library.

Example:

Original docker command:

docker run -d exampleApp:tag

Modified command:

docker run -d \
    -v /etc/apo:/etc/apo \
    -e LD_PRELOAD=/etc/apo/instrument/libapolanucher.so \
    exampleApp:tag