Task Definition runtimePlatform: unable to place a task ... the closest matching container-instance is missing an attribute required by your task

Question

When I create a new task definition revision from an existing definition now it automatically adds a `runtimePlatform` but deployment gets stuck with 
> unable to place a task because no container instance met all of its requirements. The closest matching container-instance is missing an attribute required by your task.

If create my new revision **with JSON** and **ignore** the `runtimePlatform` my service **deploys with no issues**. This is the part that confuses me the most, it does deploy if I ignore `runtimePlatform`. I've tried Linux/X86_64 (which is the OS we use), Linux/ARM64, and some of the Windows options and none of them work, always get the same issue as quoted above. What attribute am I missing?

Accepted Answer

I assume that you got a recent AMI for your EC2 with all updates.
To be sure, you can restart all EC2 in your ECS Cluster or restart all ECS agents in each EC2 instance.

Also, the ECS agent must be updated, if it's not the case.
According to the documentation, the version of ECS agent must be 1.74.1.
https://github.com/aws/amazon-ecs-agent/blob/master/CHANGELOG.md

Answer

Hi,

Are you sure about your spelling ?
It's **LINUX ** instead of Linux
And you have to define separately
```
    "runtimePlatform": {
        "operatingSystemFamily": "LINUX",
        "cpuArchitecture": "X86_64"
    },
```
https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task_definition_parameters.html#runtime-platform

Task Definition runtimePlatform: unable to place a task ... the closest matching container-instance is missing an attribute required by your task

Relevant content