Quickly make 100 service accounts and generate keys for them

create_service.sh

#!/bin/bash
# requires gcloud command line tools; go to https://cloud.google.com/sdk/docs/quickstarts to get them
# max 100 service accounts per project
# run gcloud init --console-only first and select a project
KEYS_DIR=keys
for name in service{1..100}; do echo $name; done | parallel --citation -j100 gcloud iam service-accounts create {}
for name in $(gcloud iam service-accounts list --format='value(email)'); do echo $name; done | parallel --citation -j100 gcloud iam service-accounts keys create $KEYS_DIR/{}.json --iam-account={}
gcloud iam service-accounts list --format='value(email)'