Amazon CloudWatch Publisher

Amazon CloudWatch provides a wealth of tools for monitoring resources and applications in real-time. However, out-of-the-box support is limited to AWS-native resources (e.g. EC2 instances) or systems compatible with the CloudWatch Agent.

The purpose of this tool is to expand CloudWatch monitoring support to additional platforms, essentially any that can run Python. It has been explicitly tested on (and includes daemon installers for) MacOS and the Raspberry Pi.

It supports authentication using locally-stored AWS credentials, a Cognito user, or IoT X.509 certificates.

Getting Started

Prerequisites

The publisher itself requires the following runtime dependencies:

Python 3 with pip
A shell with the tail command available (which the script uses to watch log files)
A number of Python packages, install with the following:

pip3 install -r requirements.txt

Installation

The publisher uses a JSON file to provide configuration. The format of this file is based on the configuration used by the default CloudWatch Agent, but it does not support all those options, and it adds its own unique configuration items. There are example config files in the configs folder of the repository.

The location of the config file can be provided to the script via command line parameter, or if omitted it is assumed to be at /opt/aws/amazon-cloudwatch-publisher/etc/amazon-cloudwatch-publisher.json (again to mimic the behavior of the default agent).

The config file has three top level keys: agent, metrics, and logs.

Agent

This section contains general configuration for the script. All keys are optional.

instance: Has three potential subkeys, prefix, serial and command. These values are used to construct a unique identifier for the system on which the publisher is being run. To construct the identifier, the command string is executed on the system using the shell to return a unique identifying number (e.g. on MacOS it queries the system profiler for the hardware serial number), or the serial field can provide a hardcoded number (note that if both are provided the command will be ignored and serial will be used). This number is then joined to the prefix string with a dash to form the final identifier (e.g. osx-c02v41p2hv2f). If this key is not provided, a default of sys-000000000000 is used, which is okay for testing but not suitable for production.
authentication: See the next subsection for details on the authentication options.
region: AWS region identifier (e.g. us-west-2) to which metrics and logs should be published. This value is required only if the above authentication section is provided, otherwise it is ignored and the region configured via the AWS CLI profile (environment variable or ~/.aws/config file) is used.
metrics_collection_interval: How often (in seconds) metric values should be sent to CloudWatch. Defaults to 300 seconds (5 minutes) if not provided.
logs_collection_interval: How often (in seconds) outstanding log entries should be sent to CloudWatch. Defaults to 10 seconds if not provided. This needs to be set to strike a balance between being too chatty and waiting too long to send logs that are rapidly generated, as there is a limit on how much log data can be sent in a single call to CloudWatch, see the put-log-events doc page for details.
logfile: Full path and filename to which the publisher's own log file should be written. Defaults to /opt/aws/amazon-cloudwatch-publisher/logs/amazon-cloudwatch-publisher.log (to mimic the default agent) if not provided. Do not configure the publisher to publish the output of this log file itself when debugging is turned on, otherwise a portal of infinite recursion will open up and consume the universe. You have been warned.
debug: When true, includes additional information in the above log. Defaults to false, which is recommended for normal operation.

Authentication

For non-production or testing of the publisher, omit the authentication key from the config altogether, and the script will use the AWS credentials stored in the usual way (i.e. files in the .aws folder under the home folder) See the AWS CLI documentation for more details.

For Cognito authentication, the following subkeys should be included under authentication (an example of which is in the configs/amazon-cloudwatch-publisher-osx.json file). All values are printed when the deploy-cognito.py script is run to configure the authentication back-end (more details in the Deployment section below):

accountId: The 12 digit AWS account ID to authenticate into.
userPoolId: The Cognito user pool identifier, e.g. us-east-1_xxxxxxxxx.
identityPoolId: The Cognito identity pool identifier, e.g. us-east-1:00000000-0000-0000-0000-000000000000.
appClientId: The Cognito user pool app client identifier, e.g. a1b2c3d4e5f6g7h8i9j0k1l2m3
password: The random password for the associated Cognito username that matches this system's unique instance identifier. This will be output only once from the deployment script so be sure to grab it, else the user will need to be re-created.

For IoT X.509 authentication, the following subkeys should be included (an example of which is in the configs/amazon-cloudwatch-publisher-iot.json file). More details on all these values can be found in the Deployment section below:

iotUrl: The IoT endpoint for the AWS account, obtainable by running aws iot describe-endpoint --endpoint-type iot:CredentialProvider.
roleAlias: Alias to the role the script will assume when authenticating; this role must have a policy with sufficient permissions (see the list in the Running section below)
thingName: Each instance of the publisher is represented as an IoT thing; this name unique identifies a thing.
certificate: The X.509 certificate for the IoT thing. This field can either be an array with two paths, to the device certificate and private key files (in that order), or it can be a single path to a file which is the concatenation of both the cert and key files.

Metrics

This section contains configuration specific to metrics gathering. Currently only one key is supported and it is optional.

namespace: The namespace under which metrics will be published. Defaults to System/Default if not provided. Note that hostname and instance identifier are automatically used as dimensions to further segregate published metrics.

Logs

This section contains configuration specific to log publishing. All keys are optional, but if omitted no logs will be pushed.

logs_collected: Contains the following subkeys:
- files: Contains one subkey, collect_list, which is array of objects with the following keys:
  - file_path: Full path to the log file to push to CloudWatch
  - include_patterns: List of regular expressions that, if provided, must match a log line for it to be included in the push to CloudWatch
  - exclude_patterns: List of regular expressions that, if provided, must not match a log line for it to be included in the push; exclude patterns take priority over include patterns when both are provided
- journal: If provided, and if the instance supports it, pushes the system journal to the log using the journalctl command. The following subkeys are supported:
  - include_patterns: List of regular expressions that, if provided, must match a log line for it to be included in the push to CloudWatch
  - exclude_patterns: List of regular expressions that, if provided, must not match a log line for it to be included in the push; exclude patterns take priority over include patterns when both are provided
log_group_name: Identifier to use for the log group under which each log file will be published. Should be unique per instance. The easiest way to do this is to put {instance_id} in the string somewhere, which the script will replace with the computed instance ID. Defaults to /system/default/{instance_id} if not provided.
retention_in_days: Number of days to retain logs; allowed values are 1, 3, 5, 7, 14, 30, 60, 90, 120, 150, 180, 365, 400, 545, 731, 1827, or 3653. If no value is provided, logs will be retained indefinitely.

Running

To run the publisher locally for testing, assuming AWS credentials are already configured properly for the CLI with adequate permissions, and a configuration file has been created, simply execute the script with ./amazon-cloudwatch-publisher PATH_TO_CONFIG_FILE.

The required permissions to run the publisher are the following:

cloudwatch:PutMetricData
logs:CreateLogGroup
logs:CreateLogStream
logs:DescribeLogGroups
logs:DescribeLogStreams
logs:PutLogEvents

Deployment

While locally-stored AWS credentials are acceptable for local execution, it's insufficient for production for a number of reasons:

Systems likely need to operate unattended and the long-lasting credentials that requires are a security risk
Credentials would either have to be shared across systems or each system would require its own IAM user, which is both a security and management challenge

Instead when used in production the script should use either the Cognito or IoT X.509 methods, both of which require some additional steps to set up their respective infrastructure. These steps should be performed on a system separate from those on which the publisher itself will run, since they require locally-configured AWS credentials with full permissions to run CloudFormation, create Cognito items, and create IoT devices and certificates.

Cognito

If using the Cognito authentication solution, the following tools are required:

Node >=10.3.0
AWS CDK (installed with npm i -g aws-cdk)
Additional Python packages (installed with pip3 install aws-cdk.core aws-cdk.aws-cognito aws-cdk.aws-iam passgen)

The deploy process executes by running ./deploy-cognito.py, which uses the AWS CDK to create the required infrastructure via code in the infrastructure folder. It also creates a set of users by reading from a text file named systems.txt. This file should contain a list of instance identifiers, one per line, that correspond to the systems running the publisher that will authenticate into Cognito.

The systems.txt file must exist, or the deployment will fail. Furthermore, the script will only add systems to the user pool that don't already exist.

After execution, the deployment script prints the passwords generated for each new user, but only for new users, so be sure to copy them elsewhere so they can be specified during each system's installation. The script will also print several other identifiers that will be needed.

IoT X.509

To use the AWS IoT Credentials Provider to authenticate via X.509, follow the instructions in this blog post to set up the necessary configuration, and note the required values which then are added to the publisher configuration's authentication section as described in the Installation section above.

Installing

Scripts are provided in the installers folder to automatically install the script as a background daemon on the following platforms:

MacOS: install-osx.bash
Raspberry Pi (or any Linux platform that uses systemd): install-rpi.bash

To use these scripts, copy the repo files to the system and execute the corresponding script with sudo. When prompted, enter the appropriate values from the deployment step above. The daemon will start when installation is done, and on all subsequent reboots.

Uninstalling

The uninstall process is platform dependent, but for the two current platforms, run the following:

MacOS: sudo launchctl unload /Library/LaunchDaemons/com.amazonaws.amazon-cloudwatch-publisher.plist
Raspberry Pi: systemctl disable amazon-cloudwatch-publisher

Limitations

The system must have a tail command to follow logs; this tool is used since it cleanly handles edge cases like rotation and files that don't exist yet when the scripts starts.
No two parsed logs can have the same base filename
The periodic push from each log file must satisfy the constraints of put_log_events; adjust logs_collection_interval accordingly
Hard cap of 50 streamed logs per publisher (matches default query limit for log streams; we could make multiple calls, but 50 seems like a reasonable maximum for a single instance)

Contributing

Pull requests are welcomed. Here are a few items that would be nice to get implemented:

Add safety check to prevent publishing of the log publisher's log if debugging
More installers / broader OS support and testing
Automated tests of some kind
Upgrade to CDKv2

Please lint all changes with flake8 --max-line-length=120 before submitting. Also review the Contributing Guidelines and the Code of Conduct.

Authors

Jud Neer ([email protected])

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.

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