Recently I was testing some log aggregation, and I needed to write data to stdout/stderr so that the logging agent could send them to the aggregator. Here's a snippet of code to run that for awhile so you can test out various scenarios.

for i in $(seq 1 51); do
    D=$(php -r "echo date('c');");
    sleep 2 \
    && kubectl exec $(kubectl get pods -l app=app-name -o json | jq -r '.items[0].metadata.name') -- sh -c "echo '$D $F' >> /proc/1/fd/2" \
    && kubectl exec $(kubectl get pods -l app=app-name -o json | jq -r '.items[0].metadata.name') -- sh -c "echo '$G' >> /proc/1/fd/2" ;
    done

Why? /dev/stdout and /dev/stderr seem to write back to the terminal or get lost altogether, but /proc/1/fd/1 is the output for 1 PID, which is the default process for the container.

Note: I set $F and $G with log data I was testing; basically just a log line starting with a date and then a stack trace.

F=$(< ~/f)
G=$(< ~/g)

aws ec2 describe-network-interfaces --filters Name=vpc-id,Values=vpc-47e4ee25 <<< check vpc being used or not