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EngFlow Company Newsletter - Q4 2023

To our EngFlow family — wishing you a peaceful and happy holiday. We look forward to working together in 2024!


courtesy of

From our early days we have set our company’s priorities in the following order: Happy Team, Happy Customers, More Happy Customers. We’d like to provide you with a few updates in that construct.

A Winter Visit

T'was the day before EngFlow went quiet, when all through the repository,
Not a PR was stirring, not even a new blog story.

The OnCall schedule was overridden for the year's tail
but all hoped that the clusters would stay hale.

The company was all snug in their beds,
While visions of ARR danced in their heads.

And I had settled down to quiet end of OnDuty,
Closing issues with comments a bit snooty.

When from PagerDuty arose such a clatter,
I sprang to Slack to see what was the matter!

I tore open #production,
To see what was the malfunction!

But there was nothing there,
Save an unhealthy pool alarm's blare.

I soothed it with a PR,
And rolled the cluster with a gentle hardy-har.

Then, while spilling her eggnog,
Our CEO said "let's get this out now as a Holiday Blog!"

(With apologies to Clement Clarke Moore)

Bazel 7 is here - and Bazel Invocation Analyzer is ready for it!

On December 11th, 2023, Bazel 7.0 LTS was released, which includes multiple changes to improve build performance. More details below!

Bazel Invocation Analyzer (BIA) is an open-source tool by EngFlow that analyses the JSON trace profiles generated by Bazel and provides suggestions on how to improve the build performance. You can download the source and run the CLI or use the web UI available at

BIA has been updated to support the internal changes introduced with the launch of Bazel 7.0 LTS, so you can continue to speed up your builds with the help of BIA. It also features new types of suggestions to help you fine-tune your builds irrespective of whether you are using Bazel 7 already or not.

Bazel Community Day – Munich

On October 23 2023, the day before the first European BazelCon, EngFlow and Tweag organized the sixth Bazel Community Day at the Salesforce office, capped off with a happy hour sponsored by Gradle.

Photo from Bazel Community Day, Munich

Photo from Bazel Community Day, Munich

Secure Builds with Credential Helpers

Secure and reproducible builds are something we'd all like, and something many of us work on regularly.

One area that is frequently overlooked in the topic is how to securely provide credentials for external services used during a build. Systems often fall back to insecure methods like passing them on the command-line or storing them in plaintext on disk.

In this post, we will provide an overview of common authentication mechanisms and why they should not be considered secure, and then introduce Credential Helpers and how they do provide secure builds.

EngFlow Company Newsletter - Q3 2023

EngFlow Belfast Meetup

A lot has happened since our last update, so we’d like to provide you with recent and relevant insights. We welcome questions and feedback, which we’ll collect via a brief survey below.

From our early days, we have set our company’s priorities in the following order: Happy Team, Happy Customers, More Happy Customers. We’d like to provide you with a few updates in that construct.

Coding in the Fast Lane with ibazel

The alternating sound of ctrl+s and ctrl+r followed by a deep sigh fill my days working on EngFlow's Build and Test UI. I mean, centering divs is already frustrating, but having to glance back and forth from one screen to another while refreshing the browser adds insult to injury. It doesn't help that being your average frontend dev I usually work with no less than a few thousand monitors. How else would I be able to look at the application, the code, and the ever present Flexbox layout cheatsheet at the same time?

Example of a minimal frontend dev's workstation

Example of a minimal frontend dev's workstation

Running CMake at scale

The main service we provide at EngFlow is Remote Execution (or RE for short). Remote Execution allows a build to run over a horizontally-scalable distributed system, thus speeding up highly parallelized builds. This parallelization is one of the features that make Bazel builds so scalable. Outside of Bazel, Buck2 and a few exotic build systems such as Chromium and AOSP, the adoption of this protocol is almost non-existent. Here at EngFlow we saw many C and C++ codebases successfully adopting RE, and decided to partner with, experts in that field, to bring CMake support to EngFlow.

Bazel Testing Tips

One of Bazel’s key features is that tests are treated as the same as other build actions. Bazel provides a uniform command line interface for running tests no matter the underlying language or test framework. While there’s much to be said about writing test rules and frameworks that mesh well with Bazel, this post will focus on the experience of running tests as a developer with bazel test. Running tests is a core software engineering workflow, so it’s not surprising Bazel has many useful features for iterating locally with a test.