One Small Step Closer to Containerising Service Binaries

Summary

Engineering teams at Grab initiated a transition to containerized microservices to standardize environments, enhance security, and decouple services from internal runtime tooling. During this migration, developers noticed that statically-linked Go service binaries were reaching bloated sizes over 100 MB. By analyzing the binaries using the open-source tool go-binsize-viz alongside the Go nm toolchain, the team visualized compiled symbols as interactive treemaps. This analysis revealed that 11 MB of unused message format symbols were being pulled in because a generic interface shared a directory with auto-generated streaming code. Restructuring the packages to isolate interfaces from generated code successfully decreased the binary size down to 78 MB.

Takeaways

1. 1

   Go imports all symbols defined within an imported directory and its transitive dependencies, rather than only the specifically referenced symbols.

2. 2

   Placing a shared interface in the same directory as auto-generated streaming models caused services to needlessly compile 11 MB of unused message symbols into their binaries.

3. 3

   Restructuring the flat package layout to separate generic interfaces from generated models reduced the target binary size from over 100 MB down to 78 MB.