Execution Modes

[nirsky]

There are 2 possible modes to use malabi.
This discussion is for talking about the pros and cons of each mode, and decide on which mode we should focus on.

Single process

In this mode, the malabi instrumentation and the test suite will be on the same process.
This is usually common for unit tests.

Pros

• Easy setup
• Does not change production code
• No need for network requests (faster)

Cons

• Can't be used with jest (Related issues: hooking to jest require mechanism jestjs/jest#11295, Jest Overwriting Require? jestjs/jest#7722, Can't be tested with Jest nodejs/require-in-the-middle#50)
• Unit tests usually have lots of mocks (will prevent span creation)

Remote process

In this mode, the malabi instrumentation will run on one process running the main service.
The test runner will run on a different process, and the spans will be fetched using HTTP requests (wrapped in malabi easy-to-use utils).
This is common for integration tests, a common setup is wiring everything using docker-compose.

Pros

• Can be used with jest
• Provides hard to get visibility for this kind of setup

Cons

• Targeted setup is less common than unit tests