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kozlone
Asked: 2020-06-18 03:19:22 +0800 CST

How to get the value of ECS_CONTAINER_METADATA_URI_V4 in AWS ECS container?

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The question is pretty straightforward but a little background always could be helpful. I need to get a container id from the container itself, and the value of it will be used as a logfile name. According to the docs ECS_CONTAINER_METADATA_URI_V4 is injected to each container. But when I'm connection to a Fargate hosted containers through SSH, there is no such variable. Which is expected and I had created the topic for that before just to make sure my guess is correct.

So, is there a way to get the value of ECS_CONTAINER_METADATA_URI_V4

ssh amazon-web-services amazon-ecs aws-fargate

2 Answers

  1. I’m pretty sure that the application running in the container will have that environment variable available.

    The problem is with ssh and bash that clear / sanitise the environment vars before you get the shell. I suggest you run the task on EC2-based ECS for testing (ie not on Fargate) and docker exec -it {container} bash into it - more likely than not you will find ECS_CONTAINER_METADATA_URI_V4 in the env.

    BTW - ssh’ing into a container is a bad bad practice. Containers are immutable, there should be no interactive access.

    Hope that helps :)

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  2. For now, I came with persisting the value of ECS_CONTAINER_METADATA_URI_V4 by saving it to file on a container startup: echo ${ECS_CONTAINER_METADATA_URI_V4} > metadata_url.txt

    So then I can access it.

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