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Amazon CloudWatch Logs
User Guide

Quick Start: Install the CloudWatch Logs Agent Using AWS OpsWorks and Chef

You can install the CloudWatch Logs agent and create log streams using AWS OpsWorks and Chef, which is a third-party systems and cloud infrastructure automation tool. Chef uses "recipes," which you write to install and configure software on your computer, and "cookbooks," which are collections of recipes, to perform its configuration and policy distribution tasks. For more information, see Chef.

The Chef recipes examples below show how to monitor one log file on each EC2 instance. The recipes use the stack name as the log group and the instance's hostname as the log stream name. If you want to monitor multiple log files, you need to extend the recipes to create multiple log groups and log streams.

Step 1: Create Custom Recipes

Create a repository to store your recipes. AWS OpsWorks supports Git and Subversion, or you can store an archive in Amazon S3. The structure of your cookbook repository is described in Cookbook Repositories in the AWS OpsWorks User Guide. The examples below assume that the cookbook is named logs. The install.rb recipe installs the CloudWatch Logs agent. You can also download the cookbook example (CloudWatchLogs-Cookbooks.zip).

Create a file named metadata.rb that contains the following code:

#metadata.rb

name             'logs'
version          '0.0.1'

Create the CloudWatch Logs configuration file:

#config.rb

template "/tmp/cwlogs.cfg" do
  cookbook "logs"
  source "cwlogs.cfg.erb"
  owner "root"
  group "root"
  mode 0644
end

Download and install the CloudWatch Logs agent:

# install.rb
 
directory "/opt/aws/cloudwatch" do
  recursive true
end

remote_file "/opt/aws/cloudwatch/awslogs-agent-setup.py" do
  source "https://s3.amazonaws.com/aws-cloudwatch/downloads/latest/awslogs-agent-setup.py"
  mode "0755"
end
 
  execute "Install CloudWatch Logs agent" do
  command "/opt/aws/cloudwatch/awslogs-agent-setup.py -n -r region -c /tmp/cwlogs.cfg"
  not_if { system "pgrep -f aws-logs-agent-setup" }
end

Note

In the above example, replace region with one of the following: us-east-1, us-west-1, us-west-2, ap-south-1, ap-northeast-2, ap-southeast-1, ap-southeast-2, ap-northeast-1, eu-central-1, eu-west-1, or sa-east-1.

This recipe uses a cwlogs.cfg.erb template file that you can modify to specify various attributes such as what files to log. For more information about these attributes, see CloudWatch Logs Agent Reference.

[general]
# Path to the AWSLogs agent's state file. Agent uses this file to maintain
# client side state across its executions.
state_file = /var/awslogs/state/agent-state


## Each log file is defined in its own section. The section name doesn't
## matter as long as its unique within this file.
#
#[kern.log]
#
## Path of log file for the agent to monitor and upload.
#
#file = /var/log/kern.log
#
## Name of the destination log group.
#
#log_group_name = kern.log
#
## Name of the destination log stream.
#
#log_stream_name = {instance_id}
#
## Format specifier for timestamp parsing.
#
#datetime_format = %b %d %H:%M:%S
#
#

[<%= node[:opsworks][:stack][:name] %>]
datetime_format = [%Y-%m-%d %H:%M:%S]
log_group_name = <%= node[:opsworks][:stack][:name].gsub(' ','_') %>
file = <%= node[:cwlogs][:logfile] %>
log_stream_name = <%= node[:opsworks][:instance][:hostname] %>

The template gets the stack name and host name by referencing the corresponding attributes in the stack configuration and deployment JSON. The attribute that specifies the file to log is defined in the cwlogs cookbook's default.rb attributes file (logs/attributes/default.rb).

default[:cwlogs][:logfile] = '/var/log/aws/opsworks/opsworks-agent.statistics.log'

Step 2: Create an AWS OpsWorks Stack

  1. Open the AWS OpsWorks console at https://console.aws.amazon.com/opsworks/.

  2. On the OpsWorks Dashboard, choose Add stack to create an AWS OpsWorks stack.

  3. On the Add stack screen, choose Chef 11 stack.

  4. For Stack name, enter a name.

  5. For Use custom Chef Cookbooks, choose Yes.

  6. For Repository type, select the repository type that you use. If you're using the above example, choose Http Archive.

  7. For Repository URL, enter the repository where you stored the cookbook that you created in the previous step. If you're using the above example, enter https://s3.amazonaws.com/aws-cloudwatch/downloads/CloudWatchLogs-Cookbooks.zip.

  8. Choose Add Stack to create the stack.

Step 3: Extend Your IAM Role

To use CloudWatch Logs with your AWS OpsWorks instances, you need to extend the IAM role used by your instances.

  1. Open the Identity and Access Management (IAM) console at https://console.aws.amazon.com/iam/.

  2. In the navigation pane, choose Policies, Create Policy.

  3. On the Create Policy page, under Create Your Own Policy, choose Select. For more information about creating custom policies, see IAM Policies for Amazon EC2 in the Amazon EC2 User Guide for Linux Instances.

  4. On the Review Policy page, for Policy Name, type a name for the policy.

  5. For Policy Document, paste in the following policy:

    {
      "Version": "2012-10-17",
      "Statement": [
        {
          "Effect": "Allow",
          "Action": [
            "logs:CreateLogGroup",
            "logs:CreateLogStream",
            "logs:PutLogEvents",
            "logs:DescribeLogStreams"
        ],
        "Resource": [
          "arn:aws:logs:*:*:*"
        ]
      }
     ]
    }
  6. Choose Create Policy.

  7. In the navigation pane, choose Roles, and then in the contents pane, for Role Name, select the name of the instance role used by your AWS OpsWorks stack. You can find the one used by your stack in the stack settings (the default is aws-opsworks-ec2-role).

    Tip

    Choose the role name, not the check box.

  8. On the Permissions tab, under Managed Policies, choose Attach Policy.

  9. On the Attach Policy page, in the table header (next to Filter and Search), choose Policy Type, Customer Managed Policies.

  10. For Customer Managed Policies, select the IAM policy that you created above and choose Attach Policy.

    For more information about IAM users and policies, see IAM Users and Groups and Managing IAM Policies in the IAM User Guide.

Step 4: Add a Layer

  1. Open the AWS OpsWorks console at https://console.aws.amazon.com/opsworks/.

  2. In the navigation pane, choose Layers.

  3. In the contents pane, select a layer and choose Add layer.

  4. On the OpsWorks tab, for Layer type, choose Custom.

  5. For the Name and Short name fields, enter the long and short name for the layer, and then choose Add layer.

  6. On the Recipes tab, under Custom Chef Recipes, there are several headings—Setup, Configure, Deploy, Undeploy, and Shutdown, which correspond to AWS OpsWorks lifecycle events. AWS OpsWorks triggers these events at these key points in instance's lifecycle, which runs the associated recipes.

    Note

    If the above headings aren't visible, under Custom Chef Recipes, choose edit.

  7. Enter logs::config, logs::install next to Setup, choose + to add it to the list, and then choose Save.

    AWS OpsWorks runs this recipe on each of the new instances in this layer, right after the instance boots.

Step 5: Add an Instance

The layer only controls how to configure instances. You now need to add some instances to the layer and start them.

  1. Open the AWS OpsWorks console at https://console.aws.amazon.com/opsworks/.

  2. In the navigation pane, choose Instances and then under your layer, choose + Instance.

  3. Accept the default settings and choose Add Instance to add the instance to the layer.

  4. In the row's Actions column, click start to start the instance.

    AWS OpsWorks launches a new EC2 instance and configures CloudWatch Logs. The instance's status changes to online when it's ready.

Step 6: View Your Logs

You should see the newly created log group and log stream in the CloudWatch console after the agent has been running for a few moments.

To view your logs, see View Log Data Sent to CloudWatch Logs.