三个etcd-go包有什么区别？

Question

There are three different etcd-go package, they are:

1. github.com/coreos/etcd
2. go.etcd.io/etcd
3. go.etcd.io/etcd/v3

According to the commit here , all the official codes have changed the package from go.etcd.io/etcd to go.etcd.io/etcd/v3 with following messages:

This change makes the etcd package compatible with the existing Go ecosystem for module versioning.

But I can't get the go.etcd.io/etcd/v3 package by go get command.

So what's the difference between these three etcd-go packages? And how to use them properly.

Thanks in advance.

Answer 1

There is a known issue in the client v3.4 with go get failing. See this issue: https://github.com/etcd-io/etcd/issues/11154

Although the issue has been closed because it is (supposedly) fixed in v3.5 , that version is not yet released (when writing this).

There are a few workarounds posted the issue above. The one that worked for us was to circumvent the incorrectly implemented go module of etcd and pin the version to a commit directly in our go.mod file:

require go.etcd.io/etcd v0.0.0-20200520232829-54ba9589114f

The clientv3 is then imported with:

import "go.etcd.io/etcd/clientv3"

Answer 2

The document for no.2 in the question points to this link

https://pkg.go.dev/go.etcd.io/etcd/clientv3?tab=doc

The package has below version and commit hash

v0.5.0 (ae9734e)

The document for no.3 in the question points to this link

https://pkg.go.dev/go.etcd.io/etcd/v3/clientv3?tab=doc

The package has below version and commit hash

v3.3.0 (c20cc05)

etcd would have made a breaking change in latest release and hence changed the module path to differ from the old path. This is a convention recommended in official Golang blog.

Read this blog. https://blog.golang.org/v2-go-modules Even though both of them point to the same repo, you have to import these versions differently like below. You can find the correct module path from go.mod file in the root of the repository.

import "go.etcd.io/etcd/clientv3"

import "go.etcd.io/etcd/v3/clientv3"