AWS Cloudwatch log output (influxdata#8639)

* Cloudwatch log output

* Fixes based on @sspaink review

* Make linter happy

* iMake LGTM happy, add new tests

plugins/outputs/all/all.go

@@ -8,6 +8,7 @@ import (
 	_ "github.com/influxdata/telegraf/plugins/outputs/azure_monitor"
 	_ "github.com/influxdata/telegraf/plugins/outputs/cloud_pubsub"
 	_ "github.com/influxdata/telegraf/plugins/outputs/cloudwatch"
+	_ "github.com/influxdata/telegraf/plugins/outputs/cloudwatch_logs"
 	_ "github.com/influxdata/telegraf/plugins/outputs/cratedb"
 	_ "github.com/influxdata/telegraf/plugins/outputs/datadog"
 	_ "github.com/influxdata/telegraf/plugins/outputs/discard"

plugins/outputs/cloudwatch_logs/README.md

@@ -0,0 +1,78 @@
+## Amazon CloudWatch Logs Output for Telegraf
+
+This plugin will send logs to Amazon CloudWatch.
+
+## Amazon Authentication
+
+This plugin uses a credential chain for Authentication with the CloudWatch Logs
+API endpoint. In the following order the plugin will attempt to authenticate.
+1. Assumed credentials via STS if `role_arn` attribute is specified (source credentials are evaluated from subsequent rules)
+2. Explicit credentials from `access_key`, `secret_key`, and `token` attributes
+3. Shared profile from `profile` attribute
+4. [Environment Variables](https://github.com/aws/aws-sdk-go/wiki/configuring-sdk#environment-variables)
+5. [Shared Credentials](https://github.com/aws/aws-sdk-go/wiki/configuring-sdk#shared-credentials-file)
+6. [EC2 Instance Profile](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/iam-roles-for-amazon-ec2.html)
+
+The IAM user needs the following permissions ( https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/permissions-reference-cwl.html):
+- `logs:DescribeLogGroups` - required for check if configured log group exist	
+- `logs:DescribeLogStreams` - required to view all log streams associated with a log group. 
+- `logs:CreateLogStream` - required to create a new log stream in a log group.) 
+- `logs:PutLogEvents` - required to upload a batch of log events into log stream. 
+
+## Config
+```toml
+[[outputs.cloudwatch_logs]]
+  ## The region is the Amazon region that you wish to connect to.
+  ## Examples include but are not limited to:
+  ## - us-west-1
+  ## - us-west-2
+  ## - us-east-1
+  ## - ap-southeast-1
+  ## - ap-southeast-2
+  ## ...
+  region = "us-east-1"
+
+  ## Amazon Credentials
+  ## Credentials are loaded in the following order
+  ## 1) Assumed credentials via STS if role_arn is specified
+  ## 2) explicit credentials from 'access_key' and 'secret_key'
+  ## 3) shared profile from 'profile'
+  ## 4) environment variables
+  ## 5) shared credentials file
+  ## 6) EC2 Instance Profile
+  #access_key = ""
+  #secret_key = ""
+  #token = ""
+  #role_arn = ""
+  #profile = ""
+  #shared_credential_file = ""
+
+  ## Endpoint to make request against, the correct endpoint is automatically
+  ## determined and this option should only be set if you wish to override the
+  ## default.
+  ##   ex: endpoint_url = "http://localhost:8000"
+  # endpoint_url = ""
+
+  ## Cloud watch log group. Must be created in AWS cloudwatch logs upfront!
+  ## For example, you can specify the name of the k8s cluster here to group logs from all cluster in oine place
+  log_group = "my-group-name" 
+
+  ## Log stream in log group
+  ## Either log group name or reference to metric attribute, from which it can be parsed:
+  ## tag:<TAG_NAME> or field:<FIELD_NAME>. If log stream is not exist, it will be created.
+  ## Since AWS is not automatically delete logs streams with expired logs entries (i.e. empty log stream) 
+  ## you need to put in place appropriate house-keeping (https://forums.aws.amazon.com/thread.jspa?threadID=178855)
+  log_stream = "tag:location"
+
+  ## Source of log data - metric name
+  ## specify the name of the metric, from which the log data should be retrieved.
+  ## I.e., if you  are using docker_log plugin to stream logs from container, then
+  ## specify log_data_metric_name  = "docker_log"
+  log_data_metric_name  = "docker_log"
+
+  ## Specify from which metric attribute the log data should be retrieved:
+  ## tag:<TAG_NAME> or field:<FIELD_NAME>.
+  ## I.e., if you  are using docker_log plugin to stream logs from container, then
+  ## specify log_data_source  = "field:message" 
+  log_data_source  = "field:message"
+```