Scalyr Agent (scalyr-agent-2)

CircleCI codecov Quality Gate Status

This repository holds the source code for the Scalyr Agent, a daemon that collects logs and metrics from customer machines and transmits them to Scalyr.

For more information on the Scalyr Agent, please visit

To learn more about Scalyr, visit


The Scalyr Agent is designed to be lightweight, easy to install, and safe to run on production systems. Key features:

Release Notes and Changelog

For release notes please see document and for changelog, see document.


From this repository, you can create your own RPM and Debian packages containing customized versions of the Scalyr Agent. For instance, you can bundle additional monitoring plugins to collect specialized data from your servers.

We also welcome submissions from the community.

For information on the agent architecture and code abstractions, please refer to the document.

Local Development Environment, Tests and Lint Checks

This repository utilizes tox Python project for running various lint checks and tests in isolated virtual environment.

Underneath, we use py.test test runner for running the tests.

For it to work, you need to have tox Python package installed on the system or inside the virtual environment which you use for the development.

pip install tox

In addition to that, you also need to have Python version available which is used for a particular tox target. By default Python 2.7 is used for the unit tests and Python 3.6 for all the lint checks.

To run all the checks you can simply run tox command:


In addition to that, you can also run a specific target or a set of targets using -e flag. For example:

# run all the lint targets
tox -elint

# run flake8 and mypy tox target
tox -eflake8,mypy

# run py2.7-unit-tests tox target
tox -epy2.7-unit-tests

# run coverage tox target
tox -ecoverage

To run a sub-set of tests or a single test from a test file, you can directly invoke pytest from a specific tox virtual environment as shown below:

.tox/py2.7-unit-tests/bin/py.test -vv --durations=5 "<test file>::<test class name>" -k "<test method name>"

For example:

# This will run all the tests in tests/unit/ file
.tox/py2.7-unit-tests/bin/py.test -vv --durations=5 "tests/unit/"

# This will run all the test methods on the ``UrlMonitorTestRequest`` class in the
# tests/unit/ file
.tox/py2.7-unit-tests/bin/py.test -vv --durations=5 "tests/unit/"

# This will run ``UrlMonitorTestRequest.test_get_request_no_headers`` test method from the
# tests/unit/ file
.tox/py2.7-unit-tests/bin/py.test -vv --durations=5 "tests/unit/" -k test_get_request_no_headers

Continuous Integration

We run all the tox checks described above (+ more) continuously as part of our Circle CI based build system.

Each push to a branch / pull request will trigger a build and a subset of the Circle CI jobs.

Additional jobs will run once the PR has been merged into master. The reason we do that is to speed the PR builds and increase the developer feedback loop (some of the tests and checks we run are slow so running them on every push to a branch would be slow and wasteful).

Before merging a pull request you need to ensure that all the checks have passed, pull request has been approved and it's in sync / up to date with latest master.

When all the checks have passed, you should see something like this:

In addition to that, you should trigger a full build (basically all the jobs which run on merge to master minus the agent process level benchmarks), by adding /run build comment to the PR (to avoid abuse, right now the builds can only be triggered by direct collaborators to this repository).

This will kick off our StackStorm based build automation and ensure that the whole build passes.

If the build passes, you should see a comment similar to the one below and you are free to merge your pull request.

To avoid wasting the build cycles, please make sure you only trigger the whole build once other checks which run on every PR commit have passed, PR has been approved and it's in sync with master.

If the build has failed, you can re-trigger it by adding the same comment again after you made any changes / fixes (if necessary).

After the PR has been merged, you should wait for the benchmarks workflow to complete and then check our CodeSpeed instance to ensure there are no regressions in terms of the resource utilization (memory and CPU usage) and things such as increased number of error or warning log lines.

Here is an example which demonstrates a regression in number of error level lines being printed to the agent log which likely indicates a bug / regression in the code -

Monitor Plugins

Monitor plugins are one of the key features for Scalyr Agent 2. These plugins can be used to augment the functionality of Scalyr Agent 2 beyond just copying logs and metrics. For example, there are monitor plugins that will fetch page content at a given URL and then log portions of the returned content. Another plugin allows you to execute a shell command periodically and then log the output. Essentially, plugs can be used to implement any periodic monitoring task you have.

We encourage users to create their own plugins to cover features they desire. In the near future, we will be publishing documentation that describes how to implement your own monitor. And, if you feel your monitor would be useful to other Scalyr customers, we encourage you to submit it to monitor collection in the monitors/contrib directory.

To learn how to develop plugins, please see the instructions for creating a monitor plugin.

Building Packages

You can use the script to build your own RPM or Debian packages. This is often desirable if your company has its own yum or apt repositories, or you have modified the Scalyr Agent 2 code to suit some particular need. (Of course, if you are finding you need to modify the Scalyr Agent 2 code, we encourage you to submit your changes back to the main repository).

You must have the following installed on your machine to create packages:

We strongly suggest you use the same platform that you intend to install the agent on to build the packages. This is because tools like rpmbuild and gtar are more available on the platforms that use those respective packaging systems.

To build the RPM package, execute the following command in the root directory of this repository

python rpm

To build the Debian package, execute the following command in the root directory of this repository

python deb

Pre-Commit Hooks

This project uses the Black code autoformatting tool with default settings.

Pre-commit is used to automatically run checks including Black formatting prior to a git commit.

To use pre-commit:

All the pre-commit targets rely on binaries from tox virtual environment so you need to make sure tox virtual environment for lint target exists:

tox -elint --notest --recreate

Pre-commit Configuration

To update the Pre-commit hooks , run pre-commit autoupdate. This will update .pre-commit-config.yaml and will need to be committed to the repository.


In the future, we will be pushing guidelines on how to contribute to this repository. For now, please just feel free to submit pull requests to the master branch and we will work with you.

Copyright, License, and Contributors Agreement

Copyright 2014-2020 Scalyr, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this work except in compliance with the License. You may obtain a copy of the License in the LICENSE file, or at:

By contributing you agree that these contributions are your own (or approved by your employer) and you grant a full, complete, irrevocable copyright license to all users and developers of the project, present and future, pursuant to the license of the project.