Command line arguments for the Node.js Agent – Contrast Security Support Portal

License Type	SaaS \| On-Premise
Agent Mode	Assess \| Protect
Main Product Category	Node.js Agent
Sub Category	Command line

You should use YAML configuration and environment variables for most Node.js agent configurations, however, it is possible to use command line arguments for some settings.

The Contrast Node.js agent has a help parameter that will list all the valid command line values:

Usage: node -r @contrast/agent app-main.js [agent arguments] -- [app arguments]
Options:
   -h, --help               output usage information
   -V, --version            output the version number
   -c, --configFile <path>  path to agent config file

To pass configuration options to the Node.js application being run with Contrast, use the --application.args flag, or append -- to the run command, followed by the arguments for the application.

For example, to pass appArg0 foo and appArg1 bar directly to the application, use::

npm run contrast -- --agent.logger.level debug -- --appArg0 foo --appArg1 bar

For command line arguments, the Node.js documentation shows that scripts are executed like this:

node [options] [V8 options] [script.js] [--] [arguments];

For example, if you have added a "contrast" script to your application's package.json, use:

  "scripts": {
    "contrast": "node -r @contrast/agent server.js --configFile=/home/contrast-user/contrast_agents_RHEL76/node/3.4.0/contrast_security.yaml",
      ...Background

The Contrast agent is a Node.js wrapper (runner) that invokes node to start the application. The agent doesn't pass any flags to the underlying Node.js executable, or provide the ability to do so with agent configuration options.

To pass command line flags to Node.js, you must invoke node explicitly with the agent within the scripts section of your application's package.json, followed by the name of the application's entry point file and any configuration flags, as shown above.

When the agent is installed, a symlink is created, <app-dir>/node_modules/.bin/node-contrast, which points to the file <app-dir>/node_modules/node_contrast/cli.js. You can use either of these in the script section of your application's package.json when starting the application this way.

For example:

Without the Contrast agent, you start your application like this:

node --title=MyWebsite --stack-trace-limit=25 ./index.js --env development

To run the application with the same Node.js flags and the Contrast agent, you could use either of these commands:

node --title=MyWebsite --stack-trace-limit=25 ./node_modules/.bin/node-contrast ./index.js -- --env development

node --title=MyWebsite --stack-trace-limit=25 ./node_modules/node_contrast/cli.js ./index.js -- --env development

Node.js Agent articles: