client

Documentation

Index

• Constants
• Variables
• func RemoveSequentialSuffix(path string) string
• type CannotUpdateDoesNotExistError
  • func NewCannotUpdateDoesNotExistError(path string) *CannotUpdateDoesNotExistError
  • func (e *CannotUpdateDoesNotExistError) Error() string
• type Client
  • func NewClient(servers string, sessionTimeoutSec int, username string, password string) (*Client, error)
  • func NewClientFromEnv() (*Client, error)
  • func (c *Client) Close()
  • func (c *Client) Create(path string, data []byte, acl []zk.ACL) (*ZNode, error)
  • func (c *Client) CreateSequential(path string, data []byte, acl []zk.ACL) (*ZNode, error)
  • func (c *Client) Delete(path string) error
  • func (c *Client) Exists(path string) (bool, error)
  • func (c *Client) Read(path string) (*ZNode, error)
  • func (c *Client) Update(path string, data []byte, acl []zk.ACL) (*ZNode, error)
• type MissingEnvVarError
  • func NewMissingEnvVarError(varName string) *MissingEnvVarError
  • func (e *MissingEnvVarError) Error() string
• type NonSeqZNodeCannotEndWithPathSeparatorError
  • func NewNonSeqZNodeCannotEndWithPathSeparatorError(path string) *NonSeqZNodeCannotEndWithPathSeparatorError
  • func (e *NonSeqZNodeCannotEndWithPathSeparatorError) Error() string
• type Pool
  • func NewPool() *Pool
  • func (p *Pool) GetOrCreateClient(servers string, sessionTimeoutSec int, username string, password string) (*Client, error)
• type ZNode

Constants

const (

	// EnvZooKeeperServer environment variable containing a comma separated
	// list of 'host:port' pairs, pointing at ZooKeeper Server(s).
	// This is used by NewClientFromEnv.
	EnvZooKeeperServer = "ZOOKEEPER_SERVERS"

	// EnvZooKeeperSessionSec environment variable defining how many seconds
	// a session is considered valid after losing connectivity.
	// This is used by NewClientFromEnv.
	EnvZooKeeperSessionSec = "ZOOKEEPER_SESSION"

	// DefaultZooKeeperSessionSec is the default amount of seconds configured for the
	// Client timeout session, in case EnvZooKeeperSessionSec is not set.
	DefaultZooKeeperSessionSec = 30

	// EnvZooKeeperUsername environment variable providing the username part of a digest auth credentials.
	// This is used by NewClientFromEnv.
	EnvZooKeeperUsername = "ZOOKEEPER_USERNAME"

	// EnvZooKeeperPassword environment variable providing the password part of a digest auth credentials.
	// This is used by NewClientFromEnv.
	EnvZooKeeperPassword = "ZOOKEEPER_PASSWORD"
)

Variables

var (
	ErrZNodeAlreadyExists = zk.ErrNodeExists
	ErrZNodeDoesNotExist  = zk.ErrNoNode
	ErrZNodeHasChildren   = zk.ErrNotEmpty
	ErrConnectionClosed   = zk.ErrConnectionClosed
	ErrInvalidArguments   = zk.ErrBadArguments
)

Re-exporting errors from ZK library for better encapsulation.

var (
	// ErrUserPassBothOrNone returned when only one of username and password is specified: either both or none is allowed.
	ErrUserPassBothOrNone = errors.New("both username and password must be specified together")
)

Functions

func RemoveSequentialSuffix

func RemoveSequentialSuffix(path string) string

RemoveSequentialSuffix takes the path to a sequential ZNode, maybe created via CreateSequential, and truncates the unique suffix.

See: https://zookeeper.apache.org/doc/r3.6.3/zookeeperProgrammers.html#Sequence+Nodes+--+Unique+Naming

Types

type CannotUpdateDoesNotExistError

type CannotUpdateDoesNotExistError struct {
	// contains filtered or unexported fields
}

CannotUpdateDoesNotExistError returned when a ZNode cannot be updated because it does not exist.

func NewCannotUpdateDoesNotExistError

func NewCannotUpdateDoesNotExistError(path string) *CannotUpdateDoesNotExistError

func (*CannotUpdateDoesNotExistError) Error

func (e *CannotUpdateDoesNotExistError) Error() string

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client wraps a go-zookeeper `zk.Conn` object.

It's designed to offer the functionalities that we will expose via the actual Terraform Provider.

func NewClient

func NewClient(servers string, sessionTimeoutSec int, username string, password string) (*Client, error)

NewClient constructs a new Client instance.

func NewClientFromEnv

func NewClientFromEnv() (*Client, error)

NewClientFromEnv constructs a Client instance from environment variables.

The only mandatory environment variable is EnvZooKeeperServer.

func (*Client) Close

func (c *Client) Close()

Close the Client underlying connection.

func (*Client) Create

func (c *Client) Create(path string, data []byte, acl []zk.ACL) (*ZNode, error)

Create a ZNode at the given path.

Note that any necessary ZNode parents will be created if absent.

func (*Client) CreateSequential

func (c *Client) CreateSequential(path string, data []byte, acl []zk.ACL) (*ZNode, error)

CreateSequential will create a ZNode at the given path, using the Sequential Node flag.

See: https://zookeeper.apache.org/doc/r3.6.3/zookeeperProgrammers.html#Sequence+Nodes+--+Unique+Naming

This will ensure unique naming within the same parent ZNode, by appending a monotonically increasing counter in the format `%010d` (that is 10 digits with 0 (zero) padding). Note that if the `path` ends in `/`, the ZNode name will be just the counter described above. For example:

• input path -> `/this/is/a/path/`
• created znode path -> `/this/is/a/path/0000000001`

Note also that any necessary ZNode parents will be created if absent.

func (*Client) Delete

func (c *Client) Delete(path string) error

Delete the given ZNode.

Note that will also delete any child ZNode, recursively.

func (*Client) Exists

func (c *Client) Exists(path string) (bool, error)

Exists checks for the existence of the given ZNode.

func (*Client) Read

func (c *Client) Read(path string) (*ZNode, error)

Read the ZNode at the given path.

func (*Client) Update

func (c *Client) Update(path string, data []byte, acl []zk.ACL) (*ZNode, error)

Update the ZNode at the given path, under the assumption that it is there.

Will return an error if it doesn't already exist.

type MissingEnvVarError

type MissingEnvVarError struct {
	// contains filtered or unexported fields
}

MissingEnvVarError returned when a necessary Environment variable is missing.

func NewMissingEnvVarError

func NewMissingEnvVarError(varName string) *MissingEnvVarError

func (*MissingEnvVarError) Error

func (e *MissingEnvVarError) Error() string

type NonSeqZNodeCannotEndWithPathSeparatorError

type NonSeqZNodeCannotEndWithPathSeparatorError struct {
	// contains filtered or unexported fields
}

NonSeqZNodeCannotEndWithPathSeparatorError returned when a non sequenzial ZNode ends with a path separator.

func NewNonSeqZNodeCannotEndWithPathSeparatorError

func NewNonSeqZNodeCannotEndWithPathSeparatorError(path string) *NonSeqZNodeCannotEndWithPathSeparatorError

func (*NonSeqZNodeCannotEndWithPathSeparatorError) Error

func (e *NonSeqZNodeCannotEndWithPathSeparatorError) Error() string

type Pool

type Pool struct {
	// contains filtered or unexported fields
}

Pool contains a pool of Client. Each client is associated to a unique set of construction parameters.

func NewPool

func NewPool() *Pool

func (*Pool) GetOrCreateClient

func (p *Pool) GetOrCreateClient(servers string, sessionTimeoutSec int, username string, password string) (*Client, error)

GetOrCreateClient retrieves (or creates) a Client. A new client is created for each unique set of construction parameters.

type ZNode

type ZNode struct {
	Path string
	Stat *zk.Stat
	Data []byte
	ACL  []zk.ACL
}

ZNode represents, obviously, a ZooKeeper Node.

While `Path` and `Data` fields are pretty self-explanatory, the `Stat` contains multiple ZooKeeper related metadata. See `zk.Stat` for details.