Copy edit and spice up the introduction for Jim's slowlog post

Author: rtyler

_posts/2020-04-27-sending-elasticache-slowlog-metrics-to-datadog.md

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+---
+layout: post
+title: "Sending ElastiCache slowlog metrics to Datadog"
+authors:
+- jimp
+tags:
+- terraform
+- elasticache
+- aws
+- monitoring
+team: Core Infrastructure
+---
+
+All managed services will have trade-offs, when we adopted AWS ElastiCache we
+could no longer use Datadog's excellent excellent [Redis
+integration](https://docs.datadoghq.com/integrations/redisdb/)
+and some killer metrics we couldn't live without.
+We deployed the [AWS ElastiCache
+integration](https://docs.datadoghq.com/integrations/amazon_elasticache/#overview).
+for Datadog which returned some of the desired metrics back to our dashbards
+with one notable exception: "slowlog" metrics. The Redis
+[`SLOWLOG`](https://redis.io/commands/slowlog) is used to help identify queries
+which are taking too long to execute. We use the slowlog metrics provided by the
+Datadog Redis integration alert us when a Redis server's behavior starts to go
+south, a key indicator of looming user-impactful production issues.
+
+Since AWS ElastiCache is a managed service, we obviously cannot deploy a
+Datadog agent onto AWS' servers to run the Datadog Redis integration. The
+approach we have taken, which we have now open sourced, is to use AWS Lambda to
+periodically query our ElastiCache Redis instances and submit the missing
+slowlog metrics _directly_ to Datadog, just as the Redis integration would have
+done.  
+
+## The Lambda job
+
+The first part of the equation is our Lambda job:
+[elasticache-slowlog-to-datadog](https://github.com/scribd/elasticache-slowlog-to-datadog)
+which connects to an AWS ElastiCache host (determined by the `REDIS_HOST` parameter),
+gather its slowlogs, and submit a
+[`HISTOGRAM`](https://docs.datadoghq.com/developers/metrics/types/?tab=histogram)
+metric type to Datadog. Basically mirroring the functionality of the Datadog Redis integration.
+
+The application is packaged with its required libraries as a ready-to-deploy
+archive in our [releases
+page](https://github.com/scribd/elasticache-slowlog-to-datadog/releases). To
+deploy directly to AWS from the console, upload the “Full zip distribution” and
+supply the [required
+parameters](https://github.com/scribd/elasticache-slowlog-to-datadog#parameters).
+I’d recommend using our Terraform wrapper, however.
+
+## The Terraform wrapper
+
+The second part of the equation is the Terraform module:
+[terraform-elasticache-slowlog-to-datadog](https://github.com/scribd/terraform-elasticache-slowlog-to-datadog)
+which will apply the elasticache-slowlog-to-datadog Lambda job to target AWS accounts
+and ElastiCache instances. 
+
+When Lambda jobs include libraries that must be vendored in, as
+`elasticache-slowlog-to-datadog` does, the existing patterns include [building
+locally, or uploading artifacts to
+S3](https://www.terraform.io/docs/providers/aws/r/lambda_function.html#specifying-the-deployment-package).
+However, I like the approach of maintaining a separate repository and build
+pipeline, as this works around Terraform’s [intentionally limited build
+functionality](https://github.com/hashicorp/terraform/issues/8344#issuecomment-361014199).
+In essence, the terraform wrapper merely [consumes the
+elasticache-slowlog-to-datadog
+artifact](https://github.com/scribd/terraform-elasticache-slowlog-to-datadog/blob/master/main.tf#L97).
+
+## Usage
+
+To deploy elasticache-slowlog-to-datadog via Terraform, add the following to your terraform file: 
+
+```
+module slowlog_check {
+  source                      = "git::https://github.com/scribd/terraform-elasticache-slowlog-to-datadog.git?ref=master"
+  elasticache_endpoint        = "master.replicationgroup.abcdef.use2.cache.amazonaws.com"
+  elasticache_security_groups = ["sg-12345"]
+  subnet_ids                  = [ "subnet-0123456789abcdef", "subnet-abcdef1234567890", "subnet-1234567890abcdef", ]
+  vpc_id                      = "vpc-0123456789abcdef"
+  datadog_api_key             = "abc123"
+  datadog_app_key             = "abc123"
+  namespace                   = "example"
+  env                         = "dev"
+  tags                        = {"foo" = "bar"}
+}
+```
+
+## Conclusion
+
+Using AWS Lambda, we can supplement the metrics we get natively from Datadog’s AWS ElastiCache integration. 
+
+Stay apprised of future developments by watching our release pages: 
+
+- [elasticache-slowlog-to-datadog](https://github.com/scribd/elasticache-slowlog-to-datadog/releases)
+- [terraform-elasticache-slowlog-to-datadog](https://github.com/scribd/terraform-elasticache-slowlog-to-datadog/releases)

_posts/2020-04-28-elasticache-slowlog-metrics-for-datadog.md

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+---
+layout: tag_page
+title: "Tag: elasticache"
+tag: elasticache
+robots: noindex
+---