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pkg/store: Update documentation with latest changes 

Signed-off-by: Alexandre Beslic <abronan@docker.com>
This commit is contained in:
Alexandre Beslic 2015-05-28 12:07:10 -07:00
parent 5379bdfd20
commit 1ccbf98ea0
1 changed files with 25 additions and 21 deletions
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46
pkg/store/README.md
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@ -1,6 +1,10 @@
# Storage # Storage
This package is used by the discovery service to register machines inside the cluster. It is also used to store cluster's metadata. The goal of `pkg/store` is to abstract common store operations for multiple Key/Value backends.
For example, you can use it to store your metadata or for service discovery to register machines and endpoints inside your cluster.
As of now, `pkg/store` offers support for `Consul`, `Etcd` and `Zookeeper`.
## Example of usage ## Example of usage
@ -19,15 +23,16 @@ import (
func main() { func main() {
var ( var (
// Consul local address
client = "localhost:8500" client = "localhost:8500"
) )
// Initialize a new store with consul // Initialize a new store with consul
kv, err := store.CreateStore( kv, err = store.NewStore(
store.Consul, store.CONSUL, // or "consul"
[]string{client}, []string{client},
store.Config{ &store.Config{
Timeout: 10*time.Second Timeout: 10*time.Second,
}, },
) )
if err != nil { if err != nil {
@ -35,17 +40,17 @@ func main() {
} }
key := "foo" key := "foo"
err = kv.Put(key, []byte("bar")) err = kv.Put(key, []byte("bar"), nil)
if err != nil { if err != nil {
log.Error("Error trying to put value at key `", key, "`") log.Error("Error trying to put value at key `", key, "`")
} }
value, _, err := kv.Get(key) pair, err := kv.Get(key)
if err != nil { if err != nil {
log.Error("Error trying accessing value at key `", key, "`") log.Error("Error trying accessing value at key `", key, "`")
} }
log.Info("value: ", string(value)) log.Info("value: ", string(pair.Value))
} }
``` ```
@ -57,23 +62,22 @@ A new **storage backend** should include those calls:
```go ```go
type Store interface { type Store interface {
Put(key string, value []byte) error Put(key string, value []byte, options *WriteOptions) error
Get(key string) (value []byte, lastIndex uint64, err error) Get(key string) (*KVPair, error)
Delete(key string) error Delete(key string) error
Exists(key string) (bool, error) Exists(key string) (bool, error)
Watch(key string, ttl uint64, callback WatchCallback) error Watch(key string, stopCh <-chan struct{}) (<-chan *KVPair, error)
CancelWatch(key string) error WatchTree(prefix string, stopCh <-chan struct{}) (<-chan []*KVPair, error)
Acquire(key string, value []byte) (string, error) NewLock(key string, options *LockOptions) (Locker, error)
Release(session string) error List(prefix string) ([]*KVPair, error)
GetRange(prefix string) (value [][]byte, err error) DeleteTree(prefix string) error
DeleteRange(prefix string) error AtomicPut(key string, value []byte, previous *KVPair, options *WriteOptions) (bool, *KVPair, error)
WatchRange(prefix string, filter string, heartbeat uint64, callback WatchCallback) error AtomicDelete(key string, previous *KVPair) (bool, error)
CancelWatchRange(prefix string) error
AtomicPut(key string, oldValue []byte, newValue []byte, index uint64) (bool, error)
AtomicDelete(key string, oldValue []byte, index uint64) (bool, error)
} }
``` ```
To be elligible as a **discovery backend** only, a K/V store implementation should at least offer `Get`, `Put`, `WatchRange`, `GetRange`. In the case of Swarm and to be eligible as a **discovery backend** only, a K/V store implementation should at least offer `Get`, `Put`, `WatchTree` and `List`.
`Put` should support usage of `ttl` to be able to remove entries in case of a node failure.
You can get inspiration from existing backends to create a new one. This interface could be subject to changes to improve the experience of using the library and contributing to a new backend. You can get inspiration from existing backends to create a new one. This interface could be subject to changes to improve the experience of using the library and contributing to a new backend.