keys: List a key or all keys

In ropensci/etseed: Client for 'etcd', a 'Key-value' Database

List a key or all keys

Description

List a key or all keys

Arguments

key	(character) A key name. Optional.
value	Any object to store. Required for create, update, and delete functions
recursive	Whether to do recursive something???
sorted	Whether to return sorted or not.
prevValue	(character) Previous value to match against.
prevIndex	(integer) Previous index to match against.
ttl	(integer) Seconds after which the key will be removed.
dir	(logical) Whether to crate or delete a directory or not
wait	(logical) Whether to wait or not for a key change. Deafult: FALSE
wait_index	(integer) Index to wait until
...	Further args passed on to GET

Value

All return a list, with named slots 'action' and 'node'. If the key previously existed, or is deleted, or updated, you get an addition slot 'prevNode'. The action slot tells you what action you took. the 'node' slot gives the key name, its value, a 'modifiedIndex' and a 'createdIndex'

Methods

• key: get a single key

• keys: get all keys

• create: create a key

• create_in_order: create a key in order

• update: update a key

• delete: delete a key

Headers

You can get header info on requests via curl options like key("/mykey", config = verbose()), but make sure to load httr first. Headers include in particular three useful ones that provide global information about the etcd cluster that serviced a request:

• X-Etcd-Index: the current etcd index as explained above. When request is a watch on key space, X-Etcd-Index is the current etcd index when the watch starts, which means that the watched event may happen after X-Etcd-Index.

• X-Raft-Index: similar to the etcd index but is for the underlying raft protocol

• X-Raft-Term is an integer that will increase whenever an etcd master election happens in the cluster. If this number is increasing rapidly, you may need to tune the election timeout. See the tuning (https://github.com/coreos/etcd/blob/master/Documentation/tuning.md) section for details.

Setting a key from file

Note that setting a key from a file is not working yet.

Examples

## Not run: 
# make a client
cli <- etcd()

# Make a key
cli$create(key="/mykey", value="this is awesome")
cli$create(key="/things", value="and stuff!")
## use ttl (expires after ttl seconds)
cli$create(key="/stuff", value="tables", ttl=10)

# Make a directory
cli$create(key="/mydir", dir = TRUE)
# List a directory
cli$key("/mydir")
# Make a key inside a directory
cli$create("/mydir/key1", value = "foo")
cli$create("/mydir/key2", value = "bar")
# List again, now with two keys
cli$key("/mydir")
# Delete a directory
cli$delete(key="/mydir", dir = TRUE)

# Update a key
cli$update(key="/things", value="and stuff! and more things")

# Create an in-order key
cli$create_inorder("/queue", "thing1")
cli$create_inorder("/queue", "thing2")
cli$create_inorder("/queue", "thing3")
cli$key("/queue", sorted = TRUE, recursive = TRUE)

# List all keys
cli$keys()
cli$keys(sorted = TRUE)
cli$keys(recursive = TRUE)
cli$keys(sorted = TRUE, recursive = TRUE)

# List a single key
cli$key("/mykey")
cli$key("/things")

# Waiting
## Wait for a change via long-polling
## in another R session, load etseed, then run the 2nd line of code
# cli$key("/anewkey", wait = TRUE)
# cli$create("/anewkey", "hey from another R session")
## Wait for change from cleared event index
# cli$key("/anewkey", wait = TRUE, wait_index = 7)

# Delete a key
cli$create("/hello", "world")
cli$delete("/hello")
## Delete only if matches previous value, fails
cli$delete("/things", prevValue="two")
## Delete only if matches previous index
### Fails
cli$delete("/things", prevIndex=1)
### Works
cli$delete("/things", prevIndex=13)

# curl options
library("httr")
cli$keys(config = verbose())

# Hidden keys
## Create a hidden key using "_" at beginning
cli$create("/_message", "my hidden key")
## A key that's not hidden
cli$create("/message", "my un-hidden key")
## Call to root directory doesn't show the hidden key
cli$keys()

# Set a key from a file
# cat("hello\nworld", file = "myfile.txt")
# cli$create("/myfile", file = file)

## End(Not run)

ropensci/etseed documentation built on May 18, 2022, 9:54 a.m.