使用 etcdctl · docker 從入門到實戰

## 使用 etcdctl `etcdctl` 是一個命令行客戶端，它能提供一些簡潔的命令，供用戶直接跟 `etcd` 服務打交道，而無需基于 `HTTP API` 方式。這在某些情況下將很方便，例如用戶對服務進行測試或者手動修改數據庫內容。我們也推薦在剛接觸 `etcd` 時通過 `etcdctl` 命令來熟悉相關的操作，這些操作跟 `HTTP API` 實際上是對應的。 `etcd` 項目二進制發行包中已經包含了 `etcdctl` 工具，沒有的話，可以從 [github.com/coreos/etcd/releases](https://github.com/coreos/etcd/releases) 下載。 `etcdctl` 支持如下的命令，大體上分為數據庫操作和非數據庫操作兩類，后面將分別進行解釋。 ``` NAME: etcdctl - A simple command line client for etcd3. USAGE: etcdctl VERSION: 3.2.10 API VERSION: 3.2 COMMANDS: get Gets the key or a range of keys put Puts the given key into the store del Removes the specified key or range of keys [key, range_end) txn Txn processes all the requests in one transaction compaction Compacts the event history in etcd alarm disarm Disarms all alarms alarm list Lists all alarms defrag Defragments the storage of the etcd members with given endpoints endpoint health Checks the healthiness of endpoints specified in `--endpoints` flag endpoint status Prints out the status of endpoints specified in `--endpoints` flag watch Watches events stream on keys or prefixes version Prints the version of etcdctl lease grant Creates leases lease revoke Revokes leases lease timetolive Get lease information lease keep-alive Keeps leases alive (renew) member add Adds a member into the cluster member remove Removes a member from the cluster member update Updates a member in the cluster member list Lists all members in the cluster snapshot save Stores an etcd node backend snapshot to a given file snapshot restore Restores an etcd member snapshot to an etcd directory snapshot status Gets backend snapshot status of a given file make-mirror Makes a mirror at the destination etcd cluster migrate Migrates keys in a v2 store to a mvcc store lock Acquires a named lock elect Observes and participates in leader election auth enable Enables authentication auth disable Disables authentication user add Adds a new user user delete Deletes a user user get Gets detailed information of a user user list Lists all users user passwd Changes password of user user grant-role Grants a role to a user user revoke-role Revokes a role from a user role add Adds a new role role delete Deletes a role role get Gets detailed information of a role role list Lists all roles role grant-permission Grants a key to a role role revoke-permission Revokes a key from a role check perf Check the performance of the etcd cluster help Help about any command OPTIONS: --cacert="" verify certificates of TLS-enabled secure servers using this CA bundle --cert="" identify secure client using this TLS certificate file --command-timeout=5s timeout for short running command (excluding dial timeout) --debug[=false] enable client-side debug logging --dial-timeout=2s dial timeout for client connections --endpoints=[127.0.0.1:2379] gRPC endpoints --hex[=false] print byte strings as hex encoded strings --insecure-skip-tls-verify[=false] skip server certificate verification --insecure-transport[=true] disable transport security for client connections --key="" identify secure client using this TLS key file --user="" username[:password] for authentication (prompt if password is not supplied) -w, --write-out="simple" set the output format (fields, json, protobuf, simple, table) ``` ### 數據庫操作數據庫操作圍繞對鍵值和目錄的 CRUD （符合 REST 風格的一套操作：Create）完整生命周期的管理。 etcd 在鍵的組織上采用了層次化的空間結構（類似于文件系統中目錄的概念），用戶指定的鍵可以為單獨的名字，如 `testkey`，此時實際上放在根目錄 `/` 下面，也可以為指定目錄結構，如 `cluster1/node2/testkey`，則將創建相應的目錄結構。 >注：CRUD 即 Create, Read, Update, Delete，是符合 REST 風格的一套 API 操作。 #### put ```bash $ etcdctl put /testdir/testkey "Hello world" OK ``` #### get 獲取指定鍵的值。例如 ```bash $ etcdctl put testkey hello OK $ etcdctl get testkey testkey hello ``` 支持的選項為 `--sort` 對結果進行排序 `--consistent` 將請求發給主節點，保證獲取內容的一致性 #### del 刪除某個鍵值。例如 ```bash $ etcdctl del testkey 1 ``` ### 非數據庫操作 #### watch 監測一個鍵值的變化，一旦鍵值發生更新，就會輸出最新的值。例如，用戶更新 `testkey` 鍵值為 `Hello world`。 ```bash $ etcdctl watch testkey PUT testkey 2 ``` #### member 通過 `list`、`add`、`update`、`remove` 命令列出、添加、更新、刪除 etcd 實例到 etcd 集群中。例如本地啟動一個 `etcd` 服務實例后，可以用如下命令進行查看。 ```bash $ etcdctl member list 422a74f03b622fef, started, node1, http://172.16.238.100:2380, http://172.16.238.100:23 ```