Setting default access/secret token in Minio through docker

You can use a sidecar container dependent on minio to run some mc commands which will create your new bucket, access key and policy. Here's an example:

minio-init:
  image: minio/mc
    environment:
      MINIO_ROOT_USER: ${MINIO_ROOT_USER}
      MINIO_ROOT_PASSWORD: ${MINIO_ROOT_PASSWORD}
      ACCESS_KEY: ${ACCESS_KEY}
      SECRET_KEY: ${ACCESS_SECRET}
    depends_on:
      - minio
    entrypoint: sh /init.sh
    volumes:
      - ./init.sh:/init.sh

You'll also want to add it to your pertento network so they could see eachother. Then your init.sh file will look something along these lines:

#!/bin/bash
set -e

until mc alias set local http://minio:9000 "${MINIO_ROOT_USER}" "${MINIO_ROOT_PASSWORD}" >/dev/null 2>&1; do
  sleep 1
done
echo "Minio alias set."

if mc ls local/mybucket >/dev/null 2>&1; then
  echo "Bucket 'mybucket' already exists — skipping init."
  exit 0
fi

mc mb local/mybucket
echo "Created bucket 'mybucket'."

cat >/tmp/mybucket-rw.json <<'EOF'
{
  "Version": "2012-10-17",
  "Statement": [
    { "Effect": "Allow",
      "Action": ["s3:GetBucketLocation","s3:ListBucket"],
      "Resource": ["arn:aws:s3:::mybucket"]
    },
    { "Effect": "Allow",
      "Action": ["s3:GetObject","s3:PutObject","s3:DeleteObject"],
      "Resource": ["arn:aws:s3:::mybucket/*"]
    }
  ]
}
EOF

mc admin policy create local mybucket-rw /tmp/mybucket-rw.json
echo "Policy created."

mc admin accesskey create local --access-key "$ACCESS_KEY" --secret-key "$SECRET_KEY"
echo "Access key '$ACCESS_KEY' created."

mc admin policy attach local --user "${ACCESS_KEY}" mybucket-rw
echo "Policy attached."

echo "Init complete."

I used a bucket exists check to prevent the init from running more than once, but you might want to check/update policy, etc.

Hope this helps!