Reverse order a Stream in Java

How do you reverse order a Stream in Java? There’s no obvious Stream.reverse() method. Is this an oversight in the API? Is there a workaround?

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Private DNS for Native Windows Docker Container

Docker Windows containers have a number of shortcomings, particularly around networking. One serious showstopper is that it doesn’t use the DNS of its host server.

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Initialize a Windows container with an entrypoint script

A popular Docker article describes a pattern to initialize stateful container data at runtime. The example uses a Shell script to run the initialization and then pass control to the container’s main command. We can use the same pattern to initialize a Docker Windows container.

Deploying to Google Kubernetes Engine

Previously we looked at building a Spring Cloud Data Flow on Kubernetes. As a follow up, we’re now looking at deploying to Google Kubernetes Engine. The great thing about Kubernetes you use exactly the same commands to manage a cluster on your laptop as on a server or cloud compute platform. Google has first class read more »

Spring Cloud Data Flow on Kubernetes

Spring Cloud Data Flow is a powerful tool for composing and deploying message driven data pipelines. It allows us to compose simple Spring Cloud Stream applications into complex processing pipelines. It also takes care of deploying these pipelines into Kubernetes or into Cloud Foundry. It’s powerful but has a lot of moving parts. It can read more »

Secrets in Google App Engine

Google App Engine makes it easy to deploy NodeJS applications. The GAE Standard Environment and SDK support NodeJS out of the box. This makes Google App Engine a great choice ahead of competitors such as Heroku, AWS or Microsoft Azure. Unfortunately though, there’s no support for managing secrets in Google App Engine. When I deployed Dog n Bone to GAE, I found this single shortcoming the main source of complexity.

There are however some workarounds. None of them is particularly nice though.

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Detecting Twilio API login failures

When I built out Dog n Bone – a browser phone powered by Twilio, I found that behavior on providing an incorrect accountSid / authToken was not quite what I expected. This post details how I detected Twilio API login failures in Dog n Bone.

Twilio uses ClientCapability tokens to grant access to API features. The back end obtains a ClientCapability object using a Twilio accountSid and authToken. It sets scopes on the ClientCapability to grant only necessary permissions on that account. API requests in the front end authenticate using the JWT created from the CapabilityToken. This mechanism allows the front end to authenticate to the API without exposing the Twilio accountSid / authToken.

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SSH into a Docker Container

Just sometimes, it’s useful to SSH into a Docker Container. While docker exec or docker attach are usually sufficient to run commands in a container, sometimes you specifically need SSH. For example, to connect directly from a remote machine or when an application needs to run commands on your container. Most Docker images don’t come with the SSHd service installed so it is not possible to SSH to them. This post demonstrates how to install and run the SSHd service to an existing image so that you can connect to it.

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Unit test time based logic

A standard unit testing problem is how to unit test code that has a dependency on dates or times. Consider a method that returns a greeting according to the time of day. If we were to call this method from a test fixture (say JUnit), it would return different values depending on when the test was run. This is not ideal. Unit tests should pass or fail consistently.

Here’s a simple solution for testing time based code.

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Test First React part 2: API calls and Mocks

This article demonstrates some more advanced test first React practices. Specifically, API calls and mocks.

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