[//]: # "This README.md file is auto-generated, all changes to this file will be lost."
[//]: # "To regenerate it, use `python -m synthtool`."
<img src="https://avatars2.githubusercontent.com/u/2810941?v=3&s=96" alt="Google Cloud Platform logo" title="Google Cloud Platform" align="right" height="96" width="96"/>

# [Cloud Debugger: Node.js Client](https://github.com/googleapis/cloud-debug-nodejs)

[![release level](https://img.shields.io/badge/release%20level-stable-brightgreen.svg?style=flat)](https://cloud.google.com/terms/launch-stages)
[![npm version](https://img.shields.io/npm/v/@google-cloud/debug-agent.svg)](https://www.npmjs.org/package/@google-cloud/debug-agent)




> This module provides Snapshot Debugger support for Node.js applications.
Snapshot Debugger is an open source product that lets you debug your
applications in production without stopping or pausing your application.

A Firebase Realtime Database instance is used to store your data.


A comprehensive list of changes in each version may be found in
[the CHANGELOG](https://github.com/googleapis/cloud-debug-nodejs/blob/main/CHANGELOG.md).

* [Cloud Debugger Node.js Client API Reference][client-docs]
* [Cloud Debugger Documentation][product-docs]
* [github.com/googleapis/cloud-debug-nodejs](https://github.com/googleapis/cloud-debug-nodejs)

Read more about the client libraries for Cloud APIs, including the older
Google APIs Client Libraries, in [Client Libraries Explained][explained].

[explained]: https://cloud.google.com/apis/docs/client-libraries-explained

**Table of contents:**


* [Quickstart](#quickstart)
  * [Before you begin](#before-you-begin)
  * [Installing the client library](#installing-the-client-library)

* [Samples](#samples)
* [Versioning](#versioning)
* [Contributing](#contributing)
* [License](#license)

## Quickstart

### Before you begin

1.  [Select or create a Cloud Platform project][projects].
1.  [Enable the Cloud Debugger API][enable_api].
1.  [Set up authentication with a service account][auth] so you can access the
    API from your local workstation.

### Installing the client library

```bash
npm install @google-cloud/debug-agent
```

## Debugger Agent Settings

To customize the behaviour of the automatic debugger agent, specify options
when starting the agent. The following code sample shows how to pass in a
subset of the available options.

```js
require('@google-cloud/debug-agent').start({
  // .. auth settings ..

  // debug agent settings:
  allowExpressions: true,
  serviceContext: {
    service: 'my-service',
    version: 'version-1'
  },
  capture: { maxFrames: 20, maxProperties: 100 }
});
```

The following options configure the connection to the Firebase database:
  * firebaseDbUrl - https://**PROJECT_ID**-cdbg.firebaseio.com will be used if
    not provided. where **PROJECT_ID** is your project ID.
  * firebaseKeyPath - Default google application credentials are used if not
    provided.

Some key configuration options are:
  * allowExpressions - Whether or not it is permitted to evaluate
    epressions.  Functionality is limited when this is not set, but there
    is some risk that malicious expressions can mutate program state.
  * serviceContext - This information is utilized in the UI to identify all
    the running instances of your service.  Set this if you do not like the
    default values.
  * capture - Configuration options on what is captured on a snapshot.  Set
    this if the default snapshot captures are too limited.  Note that
    relaxing constraints may cause performance impact.

See [the agent configuration][config-ts] for a list of possible configuration
options.

## Using the Debugger

Once your application is running, use the
[Snapshot Debugger CLI](https://pypi.org/project/snapshot-dbg-cli/) or the
[VSCode extension][extension-page]
to debug your application.

## Historical note

Version 6.x and 7.x of this agent supported both the now shutdown Cloud
Debugger service (by default) and the
[Snapshot Debugger](https://github.com/GoogleCloudPlatform/snapshot-debugger/)
(Firebase RTDB backend) by setting the `useFirebase` flag to true. Version 8.0.0
removed support for the Cloud Debugger service, making the Snapshot Debugger the
default.  To note the `useFirebase` flag is now obsolete, but still present for
backward compatibility.

## Limitations and Requirements

> Note: There is a known issue where enabling the agent may trigger memory
leaks.  See [#811](https://github.com/googleapis/cloud-debug-nodejs/issues/811)

* Privacy issues can be created by setting snapshot conditions that watch
  expressions evaluated in the context of your application. You may be able
  to view sensitive user data when viewing the values of variables.
* The debug agent tries to ensure that all conditions and watchpoints you
  add are read-only and have no side effects. It catches, and disallows,
  all expressions that may have static side effects to prevent accidental
  state change. However, it presently does not catch expressions that have
  dynamic side-effects. For example, `o.f` looks like a property access,
  but dynamically, it may end up calling a getter function. We presently do
  NOT detect such dynamic-side effects.
* The root directory of your application needs to contain a `package.json`
  file.

[config-ts]: https://github.com/googleapis/cloud-debug-nodejs/blob/main/src/agent/config.ts
[extension-page]: https://github.com/GoogleCloudPlatform/snapshot-debugger/tree/main/snapshot_dbg_extension
[snapshot-debugger-readme]: https://github.com/GoogleCloudPlatform/snapshot-debugger#readme


## Samples

Samples are in the [`samples/`](https://github.com/googleapis/cloud-debug-nodejs/tree/main/samples) directory. Each sample's `README.md` has instructions for running its sample.

| Sample                      | Source Code                       | Try it |
| --------------------------- | --------------------------------- | ------ |
| App | [source code](https://github.com/googleapis/cloud-debug-nodejs/blob/main/samples/app.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/cloud-debug-nodejs&page=editor&open_in_editor=samples/app.js,samples/README.md) |
| Snippets | [source code](https://github.com/googleapis/cloud-debug-nodejs/blob/main/samples/snippets.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/cloud-debug-nodejs&page=editor&open_in_editor=samples/snippets.js,samples/README.md) |



The [Cloud Debugger Node.js Client API Reference][client-docs] documentation
also contains samples.

## Supported Node.js Versions

Our client libraries follow the [Node.js release schedule](https://github.com/nodejs/release#release-schedule).
Libraries are compatible with all current _active_ and _maintenance_ versions of
Node.js.
If you are using an end-of-life version of Node.js, we recommend that you update
as soon as possible to an actively supported LTS version.

Google's client libraries support legacy versions of Node.js runtimes on a
best-efforts basis with the following warnings:

* Legacy versions are not tested in continuous integration.
* Some security patches and features cannot be backported.
* Dependencies cannot be kept up-to-date.

Client libraries targeting some end-of-life versions of Node.js are available, and
can be installed through npm [dist-tags](https://docs.npmjs.com/cli/dist-tag).
The dist-tags follow the naming convention `legacy-(version)`.
For example, `npm install @google-cloud/debug-agent@legacy-8` installs client libraries
for versions compatible with Node.js 8.

## Versioning

This library follows [Semantic Versioning](http://semver.org/).



This library is considered to be **stable**. The code surface will not change in backwards-incompatible ways
unless absolutely necessary (e.g. because of critical security issues) or with
an extensive deprecation period. Issues and requests against **stable** libraries
are addressed with the highest priority.






More Information: [Google Cloud Platform Launch Stages][launch_stages]

[launch_stages]: https://cloud.google.com/terms/launch-stages

## Contributing

Contributions welcome! See the [Contributing Guide](https://github.com/googleapis/cloud-debug-nodejs/blob/main/CONTRIBUTING.md).

Please note that this `README.md`, the `samples/README.md`,
and a variety of configuration files in this repository (including `.nycrc` and `tsconfig.json`)
are generated from a central template. To edit one of these files, make an edit
to its templates in
[directory](https://github.com/googleapis/synthtool).

## License

Apache Version 2.0

See [LICENSE](https://github.com/googleapis/cloud-debug-nodejs/blob/main/LICENSE)

[client-docs]: https://cloud.google.com/nodejs/docs/reference/debug-agent/latest
[product-docs]: https://cloud.google.com/debugger
[shell_img]: https://gstatic.com/cloudssh/images/open-btn.png
[projects]: https://console.cloud.google.com/project
[billing]: https://support.google.com/cloud/answer/6293499#enable-billing
[enable_api]: https://console.cloud.google.com/flows/enableapi?apiid=clouddebugger.googleapis.com
[auth]: https://cloud.google.com/docs/authentication/getting-started
