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@ -9,20 +9,18 @@ sidebar_current: "gettingstarted-kv"
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In addition to providing service discovery and integrated health checking,
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Consul provides an easy to use Key/Value store. This can be used to hold
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dynamic configuration, assist in service coordination, build leader election,
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and any thing else a developer can think to build. The [HTTP API](/docs/agent/http.html) fully
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documents the features of the K/V store.
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and anything else a developer can think to build. The
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[HTTP API](/docs/agent/http.html) fully documents the features of the K/V store.
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This page assumes you have at least one Consul agent already running.
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## Simple Usage
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To demonstrate how simple it is to get started, we will manipulate a few keys
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in the K/V store. We get started by first starting an agent in server mode:
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in the K/V store.
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```
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$ ./bin/consul agent -server -bootstrap -data-dir /tmp/consul
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...
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```
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Now, we can verify that our K/V store contains no keys:
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Querying the agent we started in a prior page, we can first verify that
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there are no existing keys in the k/v store:
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```
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$ curl -v http://localhost:8500/v1/kv/?recurse
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@ -43,7 +41,8 @@ $ curl -v http://localhost:8500/v1/kv/?recurse
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* Closing connection #0
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```
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Since there are no keys, we get a 404 response back. Now, we can put a few example keys:
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Since there are no keys, we get a 404 response back.
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Now, we can put a few example keys:
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```
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$ curl -X PUT -d 'test' http://localhost:8500/v1/kv/web/key1
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@ -58,21 +57,24 @@ $ curl http://localhost:8500/v1/kv/?recurse
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{"CreateIndex":99,"ModifyIndex":99,"Key":"web/sub/key3","Flags":0,"Value":"dGVzdA=="}]
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```
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Here we have created 3 keys, each with the value of "test". Note that the `Value` field
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returned is base64 encoded to encode non UTF8 characters. For the "web/key2" key, we set
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a `flag` value of 42. All keys support setting a 64bit integer flag value. This is opaque
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to Consul but can be used by clients.
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Here we have created 3 keys, each with the value of "test". Note that the
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`Value` field returned is base64 encoded to encode allow for non-UTF8
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characters. For the "web/key2" key, we set a `flag` value of 42. All keys
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support setting a 64bit integer flag value. This is opaque to Consul but can
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be used by clients for any purpose.
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After setting the values, we then issued a GET request to retrieve multiple
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keys using the `?recurse` parameter.
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Above we retrieved multiple keys using the "?recurse" query parameter, but fetching
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a single key is done by providing the path alone:
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You can also fetch a single key just as easily:
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```
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$ curl http://localhost:8500/v1/kv/web/key1
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[{"CreateIndex":97,"ModifyIndex":97,"Key":"web/key1","Flags":0,"Value":"dGVzdA=="}]
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```
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Deleting keys is simple as well. We can delete a single key by specifying the full
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path, or we can recursively delete all keys under a root using "?recurse":
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Deleting keys is simple as well. We can delete a single key by specifying the
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full path, or we can recursively delete all keys under a root using "?recurse":
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```
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$ curl -X DELETE http://localhost:8500/v1/kv/web/sub?recurse
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@ -81,9 +83,11 @@ $ curl http://localhost:8500/v1/kv/web?recurse
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{"CreateIndex":98,"ModifyIndex":98,"Key":"web/key2","Flags":42,"Value":"dGVzdA=="}]
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```
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A key can be updated by setting a new value. Additionally, Consul provides a Check-And-Set
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operation, that enables an atomic key update. This is done by providing the "?cas=" parameter
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with the last `ModifyIndex` value. For example, suppose we wanted to update "web/key1":
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A key can be updated by setting a new value by issuing the same PUT request.
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Additionally, Consul provides a Check-And-Set operation, enabling atomic
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key updates. This is done by providing the `?cas=` paramter with the last
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`ModifyIndex` value from the GET request. For example, suppose we wanted
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to update "web/key1":
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```
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$ curl -X PUT -d 'newval' http://localhost:8500/v1/kv/web/key1?cas=97
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