I'm using kaniko image to push an image to a private docker register, and it gives me No matching credentials were found, falling back on anonymous.

docker run  -v $PWD:/workspace \
        -v /root/.docker/config.json:/kaniko/config.json \
        --env DOCKER_CONFIG=/kaniko \
        gcr.io/kaniko-project/executor:latest \
        -d gitlab.xxx.org/xxx/xxx

the config.json file is valid as I verified with docker login I aslo follow kaniko gitlab to run kaniko in k8s, and get the same error