ECSPlugin: could not obtain the container id from /proc/self/cgroup

[lucaas-webpi]

I embedded xray sdk into my java program running in ECS service to send xray traces to CloudWatch.
The ECSPlugin is using com.amazonaws.xray.utils.DockerUtils to get the container id from file /proc/self/cgroup. The DockerUtils could not get the container id from /proc/self/cgroup because the program is running within the docker container.
We do have ECS metadata endpoint V4 activated and the container id should be obtained from the metadata.

[mxiamxia]

Applications running inside Container should be able to access cgroup file. Do you see any errors from your application logs?

[lucaas-webpi]

Applications running inside Container should be able to access cgroup file. Do you see any errors from your application logs?

The cgroup file in the docker container doesn't contain a container ID.

bash-4.2# cat /proc/self/cgroup
0::/

Here are logs from application:

com.amazonaws.xray.AWSXRayRecorderBuilder lambda$build$1
INFO: Collecting trace metadata from com.amazonaws.xray.plugins.ECSPlugin.
com.amazonaws.xray.utils.DockerUtils getContainerId
WARNING: Failed to read container ID because file:/proc/self/cgroup didn't contain an ID.

[srprash]

As per this code, when container id is not found via DockerUtil, the container metadata is queried for this information by making a request to the ECS_CONTAINER_METADATA_URI_V4 endpoint.

A few things to try:

1. Can you ensure you're able to access the container metadata endpoint? Something like curl $ECS_CONTAINER_METADATA_URI_V4 should be able to get you the information.
2. Do you see any logs from the ECSMetadataFetcher class indicating there was a problem fetching the metadata?
3. What kind of ECS launch type are you using? I believe Fargate type doesn't expose container information in the /proc/self/cgroup.