justeat / je.embeddedchecks

Micro-framework for embedding checks inside applications, so they tell you when they're healthy and how.

JE.EmbeddedChecks

The point

TL;DR

0. embed checks in your applications
1. trigger them from some regular event (eg, load balancer ping, cron, etc)
2. publish check pass/fail information to monitoring
3. -> operators know where to start looking, very quickly, when checks fail

• ... instead of digging through logs or paging other engineers

Continuous delivery feedback cycles become shorter.

Pipelines become simpler to orchestrate.

In detail

It's really useful for applications to proactively tell operators which parts of themselves are healthy vs unhealthy. Load balancers are a good example. A standard pattern is to ping a web-server's endpoint to see whether to include that web-server in the load-balanced cluster, or not. If the web-server is ready to included, it responds with 200 OK, otherwise anything else.

This is a good "presence" check - "I am here", but if the web-server says "no" or fails to respond, the operator must go and delve in logs to find out why.

Embedded checks take this idea further:

• Check dependencies. Covers:
  • Configuration
  • Reachability
  • Response times
• Check functionality, against stubbed responses

Embedded checks are a way to save the operator time:

• The checks allow the operator to triangulate to the root cause very quickly
• The checks can run in any environment, not just production
• The checks' history allow more advanced resiliency patterns like circuit breakers some data to decide whether to open or close

Embedded checks are a way to save engineers time:

• onboarding is simpler - clone, run, see whether checks pass. If they don't, the checks have clues for how to make progress
  • application is now more self-documenting
  • dependencies are now more clearly surfaced

Features

Embedded check definition + runner

How to contribute

See CONTRIBUTING.md.

How to release

See CONTRIBUTING.md.