The `upload` condition includes both uploads to new files and overwrite of existing ones. If an upload is aborted for quota limits SFTPGo tries to remove the partial file, so if the notification reports a zero size file and a quota exceeded error the file has been deleted. The `ssh_cmd` condition will be triggered after a command is successfully executed via SSH. `scp` will trigger the `download` and `upload` conditions and not `ssh_cmd`.
For cloud backends directories are virtual, they are created implicitly when you upload a file and are implicitly removed when the last file within a directory is removed. The `mkdir` and `rmdir` notifications are sent only when a directory is explicitly created or removed.
The `pre-delete` action, if defined, will be called just before files deletion. If the external command completes with a zero exit status or the HTTP notification response code is `200` then SFTPGo will assume that the file was already deleted/moved and so it will not try to remove the file and it will not execute the hook defined for the `delete` action.
The `pre-download` and `pre-upload` actions, will be called before downloads and uploads. If the external command completes with a zero exit status or the HTTP notification response code is `200` then SFTPGo allows the operation, otherwise the client will get a permission denied error.
-`SFTPGO_ACTION_FILE_SIZE`, non-zero for `pre-upload`,`upload`, `download` and `delete` actions if the file size is greater than `0`
-`SFTPGO_ACTION_FS_PROVIDER`, `0` for local filesystem, `1` for S3 backend, `2` for Google Cloud Storage (GCS) backend, `3` for Azure Blob Storage backend, `4` for local encrypted backend, `5` for SFTP backend
-`SFTPGO_ACTION_STATUS`, integer. Status for `upload`, `download` and `ssh_cmd` actions. 1 means no error, 2 means a generic error occurred, 3 means quota exceeded error
-`SFTPGO_ACTION_OPEN_FLAGS`, integer. File open flags, can be non-zero for `pre-upload` action. If `SFTPGO_ACTION_FILE_SIZE` is greater than zero and `SFTPGO_ACTION_OPEN_FLAGS&512 == 0` the target file will not be truncated
If the `hook` defines an HTTP URL then this URL will be invoked as HTTP POST. The request body will contain a JSON serialized struct with the following fields:
-`target_path`, string, included for `rename` action and `sftpgo-copy` SSH command
-`virtual_path`, string, virtual path, seen by SFTPGo users
-`virtual_target_path`, string, virtual target path, seen by SFTPGo users
-`ssh_cmd`, string, included for `ssh_cmd` action
-`file_size`, int64, included for `pre-upload`, `upload`, `download`, `delete` actions if the file size is greater than `0`
-`fs_provider`, integer, `0` for local filesystem, `1` for S3 backend, `2` for Google Cloud Storage (GCS) backend, `3` for Azure Blob Storage backend, `4` for local encrypted backend, `5` for SFTP backend
-`bucket`, string, inlcuded for S3, GCS and Azure backends
-`endpoint`, string, included for S3, SFTP and Azure backend if configured
-`status`, integer. Status for `upload`, `download` and `ssh_cmd` actions. 1 means no error, 2 means a generic error occurred, 3 means quota exceeded error
-`open_flags`, integer. File open flags, can be non-zero for `pre-upload` action. If `file_size` is greater than zero and `file_size&512 == 0` the target file will not be truncated
The `pre-*` actions are always executed synchronously while the other ones are asynchronous. You can specify the actions to run synchronously via the `execute_sync` configuration key. Executing an action synchronously means that SFTPGo will not return a result code to the client (which is waiting for it) until your hook have completed its execution. If your hook takes a long time to complete this could cause a timeout on the client side, which wouldn't receive the server response in a timely manner and eventually drop the connection.
-`SFTPGO_PROVIDER_ACTION`, supported values are `add`, `update`, `delete`
-`SFTPGO_PROVIDER_OBJECT_TYPE`, affetected object type
-`SFTPGO_PROVIDER_OBJECT_NAME`, unique identifier for the affected object, for example username or key id
-`SFTPGO_PROVIDER_USERNAME`, the username that executed the action. There are two special usernames: `__self__` identifies a user/admin that updates itself and `__system__` identifies an action that does not have an explicit executor associated with it, for example users/admins can be added/updated by loading them from initial data
-`SFTPGO_PROVIDER_IP`, the action was executed from this IP address
If the `hook` defines an HTTP URL then this URL will be invoked as HTTP POST. The action, username, ip, object_type and object_name and timestamp are added to the query string, for example `<hook>?action=update&username=admin&ip=127.0.0.1&object_type=user&object_name=user1×tamp=1633860803249`, and the full object is sent serialized as JSON inside the POST body with sensitive fields removed.
You can forward SFTPGo events to several publish/subscribe systems using the [sftpgo-plugin-pubsub](https://github.com/sftpgo/sftpgo-plugin-pubsub). The notifiers SFTPGo plugins are not suitable for interactive actions such as `pre-*` events. Their scope is to simply forward events to external services. A custom hook is a better choice if you need to react to `pre-*` events.
