title: gcloud auth configure-docker fail (config.json could not be read as JSON)
body: <p>I tried to push my docker image onto Google container registry, but I got an Error during authenticating gcloud service on Ubuntu 16.04:</p>
  
  <pre><code>$ gcloud auth configure-docker
  </code></pre>
  
  <p>and here is the error message I got:</p>
  
  <pre><code>ERROR: (gcloud.auth.configure-docker) Docker configuration file [/home
  /username/.docker/config.json] could not be read as JSON: could not 
  retrieve Docker client version
  </code></pre>
  
  <p>My docker version is:</p>
  
  <pre><code>Client:
      Version:    18.03.0-ce
      API version:    1.37
      Go version: go1.9.4
      Git commit: 0520e24
      Built:  Wed Mar 21 23:10:01 2018
      OS/Arch:    linux/amd64
      Experimental:   false
      Orchestrator:   swarm
  
  Server:
      Engine:
      Version:    18.03.0-ce
      API version:    1.37 (minimum version 1.12)
      Go version: go1.9.4
      Git commit: 0520e24
      Built:  Wed Mar 21 23:08:31 2018
      OS/Arch:    linux/amd64
      Experimental:   false
  </code></pre>
  
  <p>I have tried other version on Ubuntu 16.04:</p>
  
  <pre><code>$ apt-cache madison docker-ce
  </code></pre>
  
  <p>These versions are cached:</p>
  
  <pre><code>18.03.0~ce-0~ubuntu
  17.12.1~ce-0~ubuntu
  17.12.0~ce-0~ubuntu
  17.09.1~ce-0~ubuntu
  17.09.0~ce-0~ubuntu
  17.06.2~ce-0~ubuntu
  17.06.1~ce-0~ubuntu ...
  </code></pre>
  
  <p>and my config.json is:</p>
  
  <pre><code>{
   "auths": {},
   "credHelpers": {
     "asia.gcr.io": "gcr",
     "eu.gcr.io": "gcr",
     "gcr.io": "gcr",
     "staging-k8s.gcr.io": "gcr",
     "us.gcr.io": "gcr"
   }
  }
  </code></pre>