fix: Correctly configure Log4JS when running in ECS - #16355
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Within ECS, it is common to write logs to stdout/stderr and have a sidecar process the logs. This change configures Log4JS for this. Note that there is only one appender, as it looks like the presence of a `fileAppender` causes Log4JS to attempt a `mkdir` which is currently restricted in our image. See also #16341.
The aim here is to confirm the production image works before running on AWS ECS, as its slightly easier to debug any issues locally.
akash1810
marked this pull request as ready for review
July 9, 2026 11:06
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arelra
approved these changes
Jul 9, 2026
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Seen on PROD (merged by @akash1810 11 minutes and 25 seconds ago) Please check your changes! |
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After being deployed, logs are still appearing in Central ELK: 
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Recommended to review commit by commit.
What does this change?
The changes in #16341 didn't quite work. Confession, I hadn't fully tested it locally 😬. I have fully tested this branch! This is done via the new
docker-compose.yamlfile which first builds and runs the container, then makes a sample request to the application.If we run:
We (eventually) see the JSON formatted logs in stdout. Here's a screenshot from Docker Desktop:
Why?
Having logs as JSON in stdout means a sidecar (e.g. https://github.com/guardian/devx-logs/tree/main/ecs) can pick them up for processing.