Before starting, it is important to understand that client-go depends on two other Kubernetes projects: [k8s.io/apimachinery](https://github.com/kubernetes/apimachinery) and [k8s.io/api](https://github.com/kubernetes/api). In addition, if you are using CRDs, you probably also depend on [k8s.io/apiextensions-apiserver](https://github.com/kubernetes/apiextensions-apiserver) for the CRD client. The first exposes lower-level API mechanics (such as schemes, serialization, and type conversion), the second holds API definitions, and the third provides APIs related to CustomResourceDefinitions. In order for client-go to operate correctly, it needs to have its companion libraries vendored in correspondingly matching versions. Each library repository provides a branch named release-_\<version\>_ where _\<version\>_ refers to a particular Kubernetes version; for client-go version 6, it is imperative to refer to the _release_-1.9 branch on each repository.  

Assuming the latest version 5 patch release of client-go being vendored through dep, the Gopkg.toml manifest file should look something like this (possibly using branches instead of versions):  



```





[[constraint]]


  name = "k8s.io/api"

  version = "kubernetes-1.8.1"


[[constraint]]

  name = "k8s.io/apimachinery"

  version = "kubernetes-1.8.1"


[[constraint]]

  name = "k8s.io/apiextensions-apiserver"

  version = "kubernetes-1.8.1"


[[constraint]]

  name = "k8s.io/client-go"




  version = "5.0.1"

 ```


Note that some of the libraries could be missing if they are not actually needed by the client.  

Upgrading to client-go version 6 means bumping the version and tag identifiers as following ( **emphasis** given):  




```





[constraint]]


  name = "k8s.io/api"

  version = "kubernetes-1.9.0"


[[constraint]]

  name = "k8s.io/apimachinery"

  version = "kubernetes-1.9.0"


[[constraint]]

  name = "k8s.io/apiextensions-apiserver"

  version = "kubernetes-1.9.0"


[[constraint]]

  name = "k8s.io/client-go"




  version = "6.0.0"



 ```



The result of the upgrade can be found [here](https://github.com/ncdc/client-go-4-to-5/tree/v5-to-v6).  

A note of caution: dep cannot capture the complete set of dependencies in a reliable and reproducible fashion as described above. This means that for a 100% future-proof project you have to add constraints (or even overrides) to many other packages listed in client-go’s Godeps/Godeps.json. Be prepared to add them if something breaks. We are working with the golang/dep community to make this an easier and more smooth experience.  

Finally, we need to tell dep to upgrade to the specified versions by executing dep ensure. If everything goes well, the output of the command invocation should be empty, with the only indication that it was successful being a number of updated files inside the vendor folder.  

If you are using CRDs, you probably also use code-generation. The following block for Gopkg.toml will add the required code-generation packages to your project:  


```

required = [  
  "k8s.io/code-generator/cmd/client-gen",  
  "k8s.io/code-generator/cmd/conversion-gen",  
  "k8s.io/code-generator/cmd/deepcopy-gen",  
  "k8s.io/code-generator/cmd/defaulter-gen",  
  "k8s.io/code-generator/cmd/informer-gen",  
  "k8s.io/code-generator/cmd/lister-gen",  
]


[[constraint]]

  branch = "kubernetes-1.9.0"


  name = "k8s.io/code-generator"

 ```




Whether you would also like to prune unneeded packages (such as test files) through dep or commit the changes into the VCS at this point is up to you -- but from an upgrade perspective, you should now be ready to harness all the fancy new features that Kubernetes 1.9 brings through client-go.