Creating a Push Watch Folder with the API

These instructions describe how to create a push Watch Folder by using the Watch Folder API.

You can also create and manage Watch Folders from the command line (Creating a Push Watch Folder with aswatchfolderadmin) or by using IBM Aspera Console (IBM Aspera Console Admin Guide).

When you create a Watch Folder, a Watch service subscription is automatically created to monitor the source directory. In the rare case that the subscription is somehow deleted or impaired, Watch Folders automatically creates a new subscription; however, the new subscription does not retain the file change history and all files in the source directory are re-transferred.

Restrictions on all Watch Folders

Only local-to-remote (push) and remote-to-local (pull) configurations are supported. Remote-to-remote and local-to-local are not supported.
Growing files are only supported for local sources (push Watch Folders) and must be authenticated by a transfer user (password or SSH key file). The transfer user cannot be restricted to aspshell and the source cannot be in object storage.
Source file archiving is not supported if the Watch Folder source is in object storage.
IBM Aspera Shares endpoints must have version Shares version 1.9.11 with the Watch Folder patch or a later version.

To create a push Watch Folder with the API:

Prepare your computer as described in Getting Started with Watch Folders in the Command Line.
Create a Node API user and associate it with a transfer user account. The user account must have administrative (root / sudo) privileges to interact with asperawatchfolderd.
```
# /opt/aspera/bin/asnodeadmin -a -u node_username -p node_password -x admin_user --acl-set "admin,impersonation"
```
For example:
```
# /opt/aspera/bin/asnodeadmin -a -u watchfolder_user -p X245lskd3 -x root --acl-set "admin,impersonation"
```
Adding, modifying, or deleting a node-user triggers automatic reloading of the user database and the node's configuration and license files. For more information on the Node API, see your transfer server's administrator guide.

Verify that you correctly added the Node API user.

# /opt/aspera/bin/asnodeadmin -l
                        List of Node API user(s):
                user       system/transfer user                    acls
====================    =======================    ====================
       node_api_user                system_user    [admin,impersonation]

For example, using the information from the example in the previous step, the output is similar to the following:

# /opt/aspera/bin/asnodeadmin -l
                user       system/transfer user                    acls
====================    =======================    ====================
watchfolder_user                          root    [admin,impersonation]

Create the Watch service and Watch Folder service.
1. Create a JSON configuration file for each service.
  For the Watch Service:
```
{
    "type": "WATCHD",
    "run_as": {
        "user": "username",
        "pass": "password"
    },
    "enabled": true
}
```
  For the Watch Folder service:
```
{
    "type": "WATCHFOLDERD",
    "run_as": {
        "user": "username",
        "pass": "password"
    },
    "enabled": true
} 
```
  The username and password are for a transfer user with permissions to the source path. Save the files, with the .json extension.
2. To create the services, run the following command for each one:
```
# curl -ki -u node_username:node_password -X POST -d @config_file "https://localhost:9092/rund/services"
```
  If service creation succeeds, the ID of the service is returned. Record the IDs for use in the next step.
Confirm that the services are running.
For each service, run the following command:
```
# curl -ki -u node_username:node_password -X GET "https://localhost:9092/rund/services/service_id"
```
The state is reported as "RUNNING".

Create a JSON configuration file for your Watch Folder.

The Watch Folder JSON file describes the source, target, and authentication to the remote server, and can also specify transfer session settings, file handling and post-processing, filters, and growing file handling.

A basic push Watch Folder configuration file has the following syntax:

{
    "source": {
        "path": "source_directory"
    },
    "target": {
        "path": "target_directory",
        "location": {
            "type": "REMOTE",
            "host": "hostname",
            "port": port,
            "authentication": {
                "type": "authentication_mode",
                "user": "username",
                "pass": "password"
                "keypath": "key_file" 
              }
        }
    },
    "watchd": {
        "scan_period": "scan_period"
    }
}

For a full configuration reference, see Watch Folder JSON Configuration File Reference.

Field	Description	Default
source path	The local source directory. If the transfer user who is associated with the Node API user is configured with a docroot, then the path is relative to that docroot. If the transfer user is configured with a restriction, then the path is the absolute or UNC path.	N/A
target path	The remote target directory. For SSH and Node API user authentication, the path is relative to the user's docroot, or the absolute path if the transfer user is configured with a restriction. For Shares authentication, the path is the share name and, optionally, a path within the share. For access key authentication, the path is relative to the storage specified in the access key.	N/A
location type	Set `"type"` to `"REMOTE"` for the remote server. `"type": "REMOTE"` is assumed if `"host"` is specified.	`"REMOTE"`
host	The host IP address, DNS, hostname, or URL of the remote file system. Required. The host can be specified with an IPv4 or IPv6 address. The preferred format for IPv6 addresses is x:x:x:x:x:x:x:x, where each of the eight x is a hexadecimal number of up to 4 hex digits. Zone IDs (for example, %eth0) can be appended to the IPv6 address.	N/A
port	The port to use for authentication to the remote file system. By default, if the authentication type is `SSH`, then the SSH port for the ascp process (the value for `tcp_port` in the "transport" section) is used. If the authentication type is `NODE_BASIC`, 9092 is used. For Shares, IBM Aspera Transfer Cluster Manager, or IBM Aspera on Cloud endpoints, enter 443.	If authentication type is `SSH`, then default is the value for `tcp_port` in the "transport" section (default: 22). If authentication type is `NODE_BASIC`, then default is 9092.
authentication type	How Watch Folders authenticates to the remote server. Valid values are `SSH` or `NODE_BASIC`. For `SSH`, authenticate with a transfer user's username and password, or specify the username and the path to their SSH private key file. For `NODE_BASIC`, authenticate with a Node API username and password, Shares credentials, or an access key ID and secret. Sample JSON syntax for each authentication type is provided following this table.	`NODE_BASIC`
user	The username for authentication. Required. Depending on the type of authentication, it is the transfer user's username, Node API username, Shares username, or access key ID.	N/A
pass	The password for authentication. Depending on the type of authentication, it is the transfer user's password, the Node API user's password, the Shares user's password, or the access key secret. Required for SSH authentication if "keypath" is not specified	N/A
keypath	For SSH authentication with an SSH key, the path to the transfer user's SSH private key file. Required for SSH authentication if "pass" is not specified	N/A
watchd identifier	The daemon associated with the Watch Service that is used to monitor the file system. Optional. Required only when you want to use a Watch Service that is run by a user who is not associated with the Node API user or access key. Use to specify the daemon on the remote host if it is not xfer.	N/A
scan_period	The time between file system scans of the watches (from end of one to start of the next). These scans are independent of the snapshot minimum interval and snapshot minimum changes to ensure that changes are identified. To never scan (asperawatchd relies entirely on file notifications), set to "infinite". On file systems without file notifications, such as object storage, mounted storage (NFS), Solaris, AIX, and Isilon, file system scans triggered by the scan period are used to detect file changes. In this case, set the scan period to frequently scan for changes. On operating systems that support file notifications (Linux, Windows, macOS), asperawatchd uses the file notifications as the primary means for detecting changes, and the scan period serves as a backup. In this case, the default value of 30 minutes is usually acceptable and no change is necessary. To never scan, and rely entirely on file notifications, set to `infinite`. For pull Watch Folders, file systems scans that are triggered by scan_period are the sole means for detecting changes in the source directory. Lower scan periods detect changes faster but can result in greater resource consumption, particularly for object storage. Note: The value for scan period cannot be empty, otherwise the configuration is rejected.	30m

Save the configuration file. The path to the configuration file is used in the next step.

Start the Watch Folder.
```
# curl -k --user node_api_user:node_api_password -H "X-aspera-WF-version:2017_10_23" -X POST -d @path/to/json_file https://host:node_api_port/v3/watchfolders
```
By default, the API port is 9092.

Note: The header "X-aspera-WF-version:2017_10_23" is required when submitting POST, PUT, and GET requests to /v3/watchfolders on servers that are version 3.8.0 or newer. This enables Watch Folders to parse the JSON "source" and "target" objects in the format that was introduced in version 3.8.0.

For example:
```
# curl -k --user watchfolder_admin:XF324cd28 -H "X-aspera-WF-version:2017_10_23" -X POST -d @/watchfolder_conf.json https://198.51.100.22:9092/v3/watchfolders
{
"id": "b394d0ee-1cda-4f0d-b785-efdc6496c585"
}
```

Verify that the Watch Folder is running.

# curl -k --user node_api_user:node_api_password -H "X-aspera-WF-version:2017_10_23" -X GET https://host:node_api_port/v3/watchfolders/watchfolder_id/state

For example:

# curl -sk --user watchfolder_admin:XF324cd28  -H "X-aspera-WF-version:2017_10_23" -X GET https://198.51.100.22:9092/v3/watchfolders/b394d0ee-1cda-4f0d-b785-efdc6496c585/state

If the Watch Folder is running, it is reported with "state":"HEALTHY".

You can manage Watch Folders using the API. For more information, see Managing Watch Folders with the API.