A client asked me the other day: “What happens to the running executions when I update a state machine?” Sadly, the answer is likely that existing executions would break if you have changed the input/output of the Lambda functions they call. The solution is to use specific versions or aliases of the functions instead. But …
How to do blue-green deployment for Step Functions Read More »
The Serverless framework lets you reference external JSON, YML and JS files using the syntax ${file:(fileName):propertyName}. However, you can’t customize these external config files with runtime arguments. A reader asked me: “I have this boilerplate that is repeated many times in my serverless.yml, how do I reuse the boilerplate but override only specific fields?” It’s …
How to make serverless framework boilerplates customizable Read More »
I have some exciting news to share with you about the Serverless Step Functions plugin. One of the main pain points of using the plugin was that you needed to use fully-formed ARNs. We addressed this in v1.18.0 by supporting CloudFormation intrinsic functions Fn:GetAtt and Ref. This makes it possible for you to reference a …
Serverless Step Functions: no more leaky abstractions Read More »
Many clients have asked me “how do I record custom metrics from Lambda?”. Generally speaking, you can either: Publish custom metrics synchronously – e.g. send them at the end of an invocation. Publish custom metrics asynchronously by writing them to stdout first and then extracting them from CloudWatch Logs. Problems with sending custom metrics synchronously …
Introducing a better way to record custom metrics Read More »
At DAZN (where I no longer work), the teams work with a number of third-party providers. They often have to synchronize data between different AWS accounts. SNS to SQS is the primary mechanism for these cross-account deliveries because: it was an established pattern within the organization DAZN engineers and third-party engineers are both familiar with …
How to connect SNS to Kinesis for cross-account delivery via API Gateway Read More »
A while back, a client asked me “how can I share business logic between services in a Node.js monorepo?”. The TL;DR of it is: Encapsulate the shared business logic into modules, and put them in a separate folder. In the Lambda handler functions, reference the shared modules using relative paths. Use webpack to resolve and …
AWS Lambda: how to share code between functions in a monorepo Read More »
We previously discussed how you can implement an ad-hoc scheduling system using DynamoDB TTL as well as CloudWatch Events. And now, let’s see how you can implement the same system using AWS Step Functions and the pros and cons of this approach. As before, we will assess this approach using the following criteria: Precision: how …
Step Functions as an ad-hoc scheduling mechanism Read More »
Lambda makes it easy to build event-driven architectures. Each function only needs to look after its own responsibilities. We chain them together through APIs, queues, streams, and other event sources. It’s a good way to build complex systems out of simple components. We need only managed services, and we only pay for them when we …
AWS Lambda: how to detect and stop accidental infinite recursions Read More »
Imagine the situation. It’s 3 AM, and PagerDuty alerts you that the number of 5XX errors has spiked. Something’s wrong. Strange, there are no error logs… Fortunately, we have enabled X-Ray tracing and I’m able to quickly find one of the traces for these 5XX errors. Sadly, the traces don’t offer any explanation for the …
Over the last 6 months, we have made the Serverless Step Functions plugin better and more useful. Here are the most impactful changes, in case you missed it! Support for intrinsic function One of the main pain points of using the plugin has long been that you needed to use fully-formed ARNs. As of v1.18.0 …
ICYMI: five updates you’ve missed about Serverless Step Functions Read More »
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