环境准备
因为 etcd 的 API 很少，所以这里直接考虑自己写库调用，而不是用第三方库。
安装依赖
pip install grpcio pip install grpcio-tools pip install google-api-coreshell
创建 protobuf 文件
直接从官方文档抄就行了：rpc.proto。
碰到报错的 option 直接删掉就行(import 不能删，后面会讲)。
rpc.proto 是基础的服务，只用拿出你需要的服务即可，例如需要使用 Range 功能，可以这样写：
syntax = "proto3";
package etcdserverpb;
import "api/mvccpb/kv.proto";
service KV {
rpc Range(RangeRequest) returns (RangeResponse) {}
}protobuf
RangeRequest 和 RangeResponse 都在同一个文件中，部分文件例如 kv.proto 是缺失的，需要再跟着复制进来。
这里是我的目录结构，可以把它嵌套到其它目录中，但是后面的生成代码指令需要同步修改：
api ├── etcdserverpb │ └── rpc.proto └── mvccpb └── kv.protolog
例如需要使用 Range 和 Put 两个功能，完整的代码如下：
// api/etcdserverpb/rpc.proto
syntax = "proto3";
package etcdserverpb;
import "google/api/annotations.proto";
import "api/mvccpb/kv.proto";
service KV {
// Range gets the keys in the range from the key-value store.
rpc Range(RangeRequest) returns (RangeResponse) {}
// Put puts the given key into the key-value store.
// A put request increments the revision of the key-value store
// and generates one event in the event history.
rpc Put(PutRequest) returns (PutResponse) {
option (google.api.http) = {
post: "/v3/kv/put"
body: "*"
};
}
}
message RangeRequest {
enum SortOrder {
NONE = 0; // default, no sorting
ASCEND = 1; // lowest target value first
DESCEND = 2; // highest target value first
}
enum SortTarget {
KEY = 0;
VERSION = 1;
CREATE = 2;
MOD = 3;
VALUE = 4;
}
bytes key = 1;
bytes range_end = 2;
int64 limit = 3;
int64 revision = 4;
SortOrder sort_order = 5;
SortTarget sort_target = 6;
bool serializable = 7;
bool keys_only = 8;
bool count_only = 9;
int64 min_mod_revision = 10;
int64 max_mod_revision = 11;
int64 min_create_revision = 12;
int64 max_create_revision = 13;
}
message RangeResponse {
ResponseHeader header = 1;
// kvs is the list of key-value pairs matched by the range request.
// kvs is empty when count is requested.
repeated mvccpb.KeyValue kvs = 2;
// more indicates if there are more keys to return in the requested range.
bool more = 3;
// count is set to the number of keys within the range when requested.
int64 count = 4;
}
message ResponseHeader {
// cluster_id is the ID of the cluster which sent the response.
uint64 cluster_id = 1;
// member_id is the ID of the member which sent the response.
uint64 member_id = 2;
// revision is the key-value store revision when the request was applied, and it's
// unset (so 0) in case of calls not interacting with key-value store.
// For watch progress responses, the header.revision indicates progress. All future events
// received in this stream are guaranteed to have a higher revision number than the
// header.revision number.
int64 revision = 3;
// raft_term is the raft term when the request was applied.
uint64 raft_term = 4;
}
message PutRequest {
// key is the key, in bytes, to put into the key-value store.
bytes key = 1;
// value is the value, in bytes, to associate with the key in the key-value store.
bytes value = 2;
// lease is the lease ID to associate with the key in the key-value store. A lease
// value of 0 indicates no lease.
int64 lease = 3;
// If prev_kv is set, etcd gets the previous key-value pair before changing it.
// The previous key-value pair will be returned in the put response.
bool prev_kv = 4;
// If ignore_value is set, etcd updates the key using its current value.
// Returns an error if the key does not exist.
bool ignore_value = 5;
// If ignore_lease is set, etcd updates the key using its current lease.
// Returns an error if the key does not exist.
bool ignore_lease = 6;
}
message PutResponse {
ResponseHeader header = 1;
// if prev_kv is set in the request, the previous key-value pair will be returned.
mvccpb.KeyValue prev_kv = 2;
}proto
// api/mvccpb/kv.proto
syntax = "proto3";
package mvccpb;
message KeyValue {
// key is the key in bytes. An empty key is not allowed.
bytes key = 1;
// create_revision is the revision of last creation on this key.
int64 create_revision = 2;
// mod_revision is the revision of last modification on this key.
int64 mod_revision = 3;
// version is the version of the key. A deletion resets
// the version to zero and any modification of the key
// increases its version.
int64 version = 4;
// value is the value held by the key, in bytes.
bytes value = 5;
// lease is the ID of the lease that attached to key.
// When the attached lease expires, the key will be deleted.
// If lease is 0, then no lease is attached to the key.
int64 lease = 6;
}proto
生成代码
之后使用命令生成对应的 Python 代码：
python -m grpc_tools.protoc -I./ -I./.venv/Lib/site-packages --python_out=./ --pyi_out=./ api/mvccpb/kv.proto python -m grpc_tools.protoc -I./ -I./.venv/Lib/site-packages --python_out=./ --pyi_out=./ --grpc_python_out=./ api/etcdserverpb/rpc.protoshell
注意 -I./.venv/Lib/site-packages，这个就是告诉 protoc，将这个目录也作为 protoc 文件的搜素目录(实际是让它搜素该文件夹中的 google 目录)。
测试：
def main():
with grpc.insecure_channel('10.77.0.38:2379') as channel:
stub = rpc_pb2_grpc.KVStub(channel)
range_response = stub.Range(
rpc_pb2.RangeRequest(
key=bytes('/testenv', 'utf-8'),
range_end=bytes('\0', 'utf-8'),
)
)
print(range_response.kv)
if __name__ == "__main__":
main()python
Ptyhon 3.6 生成文件的问题
如果是 Python 3.6，在使用--pyi_out会报错，这个是一个声明文件的生成，不生成不会影响运行，但是会导致语法提示缺失。
首先去掉 --pyi_out。之后下载 protoc，直接用最新版就可以了(我当时是 28.0)。
然后使用下面的命令重新生成 pyi 文件。
protoc -I./ -I./.ansible-cd-venv/Lib/site-packages --pyi_out=./ api/etcdserverpb/rpc.proto protoc -I./ -I./.ansible-cd-venv/Lib/site-packages --pyi_out=./ api/mvccpb/kv.protoshell
关于 key 和 range_end
对于 key 是必须提供的，搭配上 range_end，etcd 会做出不同的行为：
- 如果
range_end为空，则精确匹配key。 - 如果
range_end为\0，则匹配所有前缀为key的项目。 - 如果
range_end为其它值，则会使用字典序匹配出所有 [key,range_end) 范围内的项目。- 例如:
fa、fb、fc、fca、fcb、fcc、fd、fe是一组字典序升序的字符串，[fb,fd) 的结果就是fb、fc、fca、fcb、fcc。
- 例如:
除此之外，如果 key 为 \0，则匹配所有键。如果要搜素所有的键，则需要指定 key = '\0'，range_end = '\0'.