Till MinIO release `RELEASE.2018-08-02T23-11-36Z`, MinIO server configuration file (`config.json`) was stored in the configuration directory specified by `--config-dir` or defaulted to `${HOME}/.minio`. However from releases after `RELEASE.2018-08-18T03-49-57Z`, the configuration file (only), has been migrated to the storage backend (storage backend is the directory passed to MinIO server while starting the server).
You can specify the location of your existing config using `--config-dir`, MinIO will migrate the `config.json` to your backend storage. Your current `config.json` will be renamed upon successful migration as `config.json.deprecated` in your current `--config-dir`. All your existing configurations are honored after this migration.
Additionally `--config-dir` is now a legacy option which will is scheduled for removal in future, so please update your local startup, ansible scripts accordingly.
TLS certificates by default are stored under ``${HOME}/.minio/certs`` directory. You need to place certificates here to enable `HTTPS` based access. Read more about [How to secure access to MinIO server with TLS](https://docs.min.io/docs/how-to-secure-access-to-minio-server-with-tls).
On MinIO admin credentials or root credentials are only allowed to be changed using ENVs namely `MINIO_ROOT_USER` and `MINIO_ROOT_PASSWORD`. Using the combination of these two values MinIO encrypts the config stored at the backend.
Additionally if you wish to change the admin credentials, then MinIO will automatically detect this and re-encrypt with new credentials as shown below. For one time only special ENVs as shown below needs to be set for rotating the encryption config.
> Old ENVs are never remembered in memory and are destroyed right after they are used to migrate your existing content with new credentials. You are safe to remove them after the server as successfully started, by restarting the services once again.
> **NOTE: Make sure to remove `MINIO_ROOT_USER_OLD` and `MINIO_ROOT_PASSWORD_OLD` in scripts or service files before next service restarts of the server to avoid double encryption of your existing contents.**
By default, parity for objects with standard storage class is set to `N/2`, and parity for objects with reduced redundancy storage class objects is set to `2`. Read more about storage class support in MinIO server [here](https://github.com/minio/minio/blob/master/docs/erasure/storage-class/README.md).
MinIO provides caching storage tier for primarily gateway deployments, allowing you to cache content for faster reads, cost savings on repeated downloads from the cloud.
```
KEY:
cache add caching storage tier
ARGS:
drives* (csv) comma separated mountpoints e.g. "/optane1,/optane2"
expiry (number) cache expiry duration in days e.g. "90"
quota (number) limit cache drive usage in percentage e.g. "90"
exclude (csv) comma separated wildcard exclusion patterns e.g. "bucket/*.tmp,*.exe"
MinIO supports storing encrypted IAM assets and bucket DNS records on etcd.
> NOTE: if *path_prefix* is set then MinIO will not federate your buckets, namespaced IAM assets are assumed as isolated tenants, only buckets are considered globally unique but performing a lookup with a *bucket* which belongs to a different tenant will fail unlike federated setups where MinIO would port-forward and route the request to relevant cluster accordingly. This is a special feature, federated deployments should not need to set *path_prefix*.
```
KEY:
etcd federate multiple clusters for IAM and Bucket DNS
ARGS:
endpoints* (csv) comma separated list of etcd endpoints e.g. "http://localhost:2379"
path_prefix (path) namespace prefix to isolate tenants e.g. "customer1/"
coredns_path (path) shared bucket DNS records, default is "/skydns"
client_cert (path) client cert for mTLS authentication
client_cert_key (path) client cert key for mTLS authentication
comment (sentence) optionally add a comment to this setting
```
or environment variables
```
KEY:
etcd federate multiple clusters for IAM and Bucket DNS
ARGS:
MINIO_ETCD_ENDPOINTS* (csv) comma separated list of etcd endpoints e.g. "http://localhost:2379"
MINIO_ETCD_PATH_PREFIX (path) namespace prefix to isolate tenants e.g. "customer1/"
MINIO_ETCD_COREDNS_PATH (path) shared bucket DNS records, default is "/skydns"
MINIO_ETCD_CLIENT_CERT (path) client cert for mTLS authentication
MINIO_ETCD_CLIENT_CERT_KEY (path) client cert key for mTLS authentication
MINIO_ETCD_COMMENT (sentence) optionally add a comment to this setting
By default, there is no limitation on the number of concurrent requests that a server/cluster processes at the same time. However, it is possible to impose such limitation using the API subsystem. Read more about throttling limitation in MinIO server [here](https://github.com/minio/minio/blob/master/docs/throttle/README.md).
MINIO_API_REQUESTS_MAX (number) set the maximum number of concurrent requests, e.g. "1600"
MINIO_API_REQUESTS_DEADLINE (duration) set the deadline for API requests waiting to be processed e.g. "1m"
MINIO_API_CORS_ALLOW_ORIGIN (csv) set comma separated list of origins allowed for CORS requests e.g. "https://example1.com,https://example2.com"
MINIO_API_REMOTE_TRANSPORT_DEADLINE (duration) set the deadline for API requests on remote transports while proxying between federated instances e.g. "2h"
Notification targets supported by MinIO are in the following list. To configure individual targets please refer to more detailed documentation [here](https://docs.min.io/docs/minio-bucket-notification-guide.html)
```
notify_webhook publish bucket notifications to webhook endpoints
notify_amqp publish bucket notifications to AMQP endpoints
notify_kafka publish bucket notifications to Kafka endpoints
notify_mqtt publish bucket notifications to MQTT endpoints
notify_nats publish bucket notifications to NATS endpoints
notify_nsq publish bucket notifications to NSQ endpoints
notify_mysql publish bucket notifications to MySQL databases
notify_postgres publish bucket notifications to Postgres databases
notify_elasticsearch publish bucket notifications to Elasticsearch endpoints
notify_redis publish bucket notifications to Redis datastores
All configuration changes can be made using [`mc admin config` get/set/reset/export/import commands](https://github.com/minio/mc/blob/master/docs/minio-admin-complete-guide.md).
The following sub-systems are dynamic i.e., configuration parameters for each sub-systems can be changed while the server is running without any restarts.
```
api manage global HTTP API call specific features, such as throttling, authentication types, etc.
heal manage object healing frequency and bitrot verification checks
Data usage scanner is enabled by default. The following configuration settings allow for more staggered delay in terms of usage calculation. The scanner adapts to the system speed and completely pauses when the system is under load. It is possible to adjust the speed of the scanner and thereby the latency of updates being reflected. The delays between each operation of the scanner can be adjusted by the `mc admin config set alias/ delay=15.0`. By default the value is `10.0`. This means the scanner will sleep *10x* the time each operation takes.
In most setups this will keep the scanner slow enough to not impact overall system performance. Setting the `delay` key to a *lower* value will make the scanner faster and setting it to 0 will make the scanner run at full speed (not recommended in production). Setting it to a higher value will make the scanner slower, consuming less resources with the trade off of not collecting metrics for operations like healing and disk usage as fast.
Example: Following setting will decrease the scanner speed by a factor of 3, reducing the system resource use, but increasing the latency of updates being reflected.
Healing is enabled by default. The following configuration settings allow for more staggered delay in terms of healing. The healing system by default adapts to the system speed and pauses up to '1sec' per object when the system has `max_io` number of concurrent requests. It is possible to adjust the `max_delay` and `max_io` values thereby increasing the healing speed. The delays between each operation of the healer can be adjusted by the `mc admin config set alias/ max_delay=1s` and maximum concurrent requests allowed before we start slowing things down can be configured with `mc admin config set alias/ max_io=30` . By default the wait delay is `1sec` beyond 10 concurrent operations. This means the healer will sleep *1 second* at max for each heal operation if there are more than *10* concurrent client requests.
In most setups this is sufficient to heal the content after drive replacements. Setting `max_delay` to a *lower* value and setting `max_io` to a *higher* value would make heal go faster.
max_sleep (duration) maximum sleep duration between objects to slow down heal operation. eg. 2s
max_io (int) maximum IO requests allowed between objects to slow down heal operation. eg. 3
```
Example: The following settings will increase the heal operation speed by allowing healing operation to run without delay up to `100` concurrent requests, and the maximum delay between each heal operation is set to `300ms`.
```sh
~ mc admin config set alias/ heal max_delay=300ms max_io=100
```
Once set the healer settings are automatically applied without the need for server restarts.
> NOTE: Healing is not supported under Gateway deployments.
By default, MinIO supports path-style requests that are of the format http://mydomain.com/bucket/object. `MINIO_DOMAIN` environment variable is used to enable virtual-host-style requests. If the request `Host` header matches with `(.+).mydomain.com` then the matched pattern `$1` is used as bucket and the path is used as object. More information on path-style and virtual-host-style [here](http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAPI.html)
