Chapter 17. ZooKeeper Console Commands
By default, the ZooKeeper commands are not installed in a Fabric Container. To make the ZooKeeper commands available, install the
fabric-zookeeper-commands feature, as follows:
features:install fabric-zookeeper-commands
17.1. zk:create
Abstract
create a znode
Synopsis
zk:create [
--help
] [
-r|--recursive
] [
-i|--import
] [
-e|--ephemeral
] [
-s|--sequential
] [
-a|--acl ListOfACLs
] [
-o|--overwrite
] {
path
} {
data
}
Description
Using this command, you can create the following different types of znode:
- Persistent
- The new znode is permanently stored in the ZooKeeper registry. This is the default.
- Persistent sequential
- The new znode is permanently stored in the ZooKeeper registry and a 10-digit sequence number is appended to the specified znode name. Selected by the
--sequentialoption. - Ephemeral
- The new znode exists only for the duration of the current client session. When the session is over, the znode is removed. Selected by the
--ephemeraloption. - Ephemeral sequential
- The new znode exists only for the duration of the current client session and a 10-digit sequence number is appended to the specified znode name. When the session is over, the znode is removed. Selected by combining the
--ephemeraloption with the--sequentialoption.
You can optionally specify a list of ACLs to apply to the newly created znode. The ACL is specified as a comma-separated list, where each entry in the list has the following format:
Scheme:ID:Permissions
ZooKeeper supports the following built-in schemes:
world:anyone- The permissions apply to all users.
auth:- The permissions apply to all authenticated users, irrespective of their identity (the
IDfield is left empty). digest:MD5Hash- The permissions apply to the user whose username and password generate the specified MD5 hash value,
MD5Hash. ip:IPAddress- The permissions apply to the ZooKeeper client with the specified IP address.
The
Permissions string consists of one or more of the following characters: r (read), w (write), c (create), d (delete), and a (admin). For example, to create a new znode that explicitly grants all permissions to all users (which is, in fact, the default), you could use a command like the following:
karaf@root> zk:create --acl world:anyone:rwcda /path/to/the/new/znode
Important
To avoid corruption of the fabric registry, you should not create any znodes under the
/fabric/ path using the zk:create command. These registry nodes should only be created through the fabric console commands—see Chapter 7, Fabric Console Commands.
Note
Fuse Fabric does not use the ACL security features of ZooKeeper. Currently, all znodes in the fabric registry are created without any ACL restrictions (equivalent to the
world:anyone:rwcda ACL setting).
Arguments
Table 17.1, “zk:create Arguments” describes the commands arguments.
| Argument | Interpretation |
|---|---|
--help | Displays the online help for this command |
-r,--recursive | Automatically create any missing parent nodes in the specified path. |
-i,--import | Interpret the data argument as a URL that locates a resource containing the initial data for the new znode. |
-e,--ephemeral | Make the new znode epehemeral, so that it is automatically deleted after the current ZooKeeper client session closes. |
-s,--sequential | Make the new znode sequential, which implies that a unique 10-digit suffix is appended to the znode name. |
-a,--acl | Specifies the znode's ACL as a comma-separated list, where each entry in the list has the format, Scheme:ID:Permissions. The Permissions string consists of the following characters, concatenated in any order: r (read), w (write), c (create), d (delete), and a (admin). |
-o,--overwrite | Overwrite the existing znode at this location, if there is one. |
path | (Required) Path of the znode to create. |
data | Initial data for the node or, if --import is specified, a URL pointing at a location that contains the initial data. |
