Update readme, add diagram

README.md

@@ -1,27 +1,45 @@
 # cw-logs-to-slack
 
-This serverless app... TODO
+This serverless app publishes AWS CloudWatch logs to Slack based on a subscription filter.
 
 ## App Architecture
 
-TODO: arch diagram
+![App Architecture](https://github.com/keetonian/cw-logs-to-slack/raw/master/images/cw-logs-to-slack.png)
 
 ## Installation Instructions
 
 1. [Create an AWS account](https://portal.aws.amazon.com/gp/aws/developer/registration/index.html) if you do not already have one and login
-1. Go to the app's page on the [Serverless Application Repository](TODO) and click "Deploy"
+1. Go to the app's page on the [Serverless Application Repository]() and click "Deploy"
 1. Provide the required app parameters (see parameter details below) and click "Deploy"
 
+### Slack Url
+To get a webhook URL for this application:
+* Navigate to https://api.slack.com
+* Click on the "Start Building" button
+* Give your app a name and select a workspace
+* Under "Add features and functionality" select "Incoming Webhooks"
+* Turn on "Incoming Webhooks" and click "Add New Webhook to Workspace"
+* Select the desired channel and click "Authorize"
+* Copy the generated Webhook URL
+
+### Log Group Name
+You can find the name of the log group by navigating to CloudWatch logs on the AWS console. You can also pass it in as a parameter from another stack or another resource (e.g. default lambda log group names are `/aws/lambda/{lambda-function-name}`).
+
+### Filter Pattern
+CloudWatch logs allow you to filter logs based on a pattern. For more information, see the [AWS Documentation](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/FilterAndPatternSyntax.html).
+
 ## App Parameters
 
+1. `SlackUrl` (required) - Webhook URL for integration with Slack
+1. `LogGroupName` (required) - Log group to listen to (has to be in same account and region)
+1. `FilterPattern` (optional) - Pattern for filtering log events. Default: ERROR
 1. `LogLevel` (optional) - Log level for Lambda function logging, e.g., ERROR, INFO, DEBUG, etc. Default: INFO
-1. ...
 
 ## App Outputs
 
-1. `MyFunctionName` - My Lambda function name.
-1. ...
+1. `LogsToSlackName` - Lambda function name.
+1. `LogsToSlackArn` - Lambda function ARN.
 
 ## License Summary
 
-This code is made available under the TODO license. See the LICENSE file.
+This code is made available under the MIT license. See the LICENSE file.