Why is Uchiwa not able to monitor the datacenter on CentOS7?

This post combined with Install Sensu using YUM was used in order to install, configure and start Sensu and related services:

sudo yum install -y erlang && \
sudo rpm -Uvh http://www.rabbitmq.com/releases/rabbitmq-server/v3.5.0/rabbitmq-server-3.5.0-1.noarch.rpm && \
sudo yum install -y redis && \
echo '[sensu]
name=sensu
baseurl=http://sensu.global.ssl.fastly.net/yum/$basearch/
gpgcheck=0
enabled=1' | sudo tee /etc/yum.repos.d/sensu.repo && \
sudo yum install -y sensu && \
sudo yum install -y uchiwa && \
for s in rabbitmq-server redis.service sensu-server sensu-api uchiwa; do sudo systemctl restart $s; done && \
sudo rabbitmqctl add_vhost /sensu && \
sudo rabbitmqctl add_user sensu secret && \
sudo rabbitmqctl set_permissions -p /sensu sensu ".*" ".*" ".*"

Analysis

• Navigating to :3000 shows the uchiwa dashboard and indicates Connection error. Is the Sensu API running?
• /var/log/sensu/sensu-api.log indicates

{"timestamp":"2016-07-03T22:58:58.532905+0000","level":"warn","message":"config file does not exist or is not readable","file":"/etc/sensu/config.json"}
{"timestamp":"2016-07-03T22:58:58.533069+0000","level":"warn","message":"ignoring config file","file":"/etc/sensu/config.json"}
{"timestamp":"2016-07-03T22:58:58.533137+0000","level":"warn","message":"loading config files from directory","directory":"/etc/sensu/conf.d"}
{"timestamp":"2016-07-03T22:58:58.712175+0000","level":"info","message":"api listening","protocol":"http","bind":"0.0.0.0","port":4567}

• The config.json does not seems to exist (/etc/sensu/config.json: No such file or directory)
• Downloading the example config.json and restarting the sensu-api did not solve the issue

{
  "rabbitmq": {
    "host": "localhost",
    "vhost": "/sensu",
    "user": "sensu",
    "password": "secret"
  },
  "redis": {
    "host": "localhost",
    "port": 6379,
    "password": "secret"
  }
}

• the redis port is listening:

LISTEN     0      128    127.0.0.1:6379                     *:*

• the rabbitmq port as well:

LISTEN     0      100          *:4567                     *:* 

• Uchiwa cannot connect to the datacenters

{
  "sensu": [
    {
      "name": "Site 1",
      "host": "localhost",
      "port": 4567,
      "timeout": 10
    },
    {
      "name": "Site 2",
      "host": "localhost",
      "port": 4567,
      "ssl": false,
      "path": "",
      "user": "",
      "pass": "",
      "timeout": 10
    }
  ],
  "uchiwa": {
    "host": "0.0.0.0",
    "port": 3000,
    "refresh": 10
  }
}

{"timestamp":"2016-07-03T23:34:32.990067621Z","level":"warn","message":"GET http://localhost:4567/stashes returned: 500 Internal Server Error"}
{"timestamp":"2016-07-03T23:34:32.990102095Z","level":"warn","message":"Connection failed to the datacenter Site 1"}
{"timestamp":"2016-07-03T23:34:32.990115588Z","level":"info","message":"Updating the datacenter Site 2"}
{"timestamp":"2016-07-03T23:34:32.991462585Z","level":"warn","message":"GET http://localhost:4567/stashes returned: 500 Internal Server Error"}
{"timestamp":"2016-07-03T23:34:32.991492978Z","level":"warn","message":"Connection failed to the datacenter Site 2"}

• navigating to <IPADDRESS>:4567 results in:

{"error":"redis and transport connections not initialized"}

• redis replies

sudo redis-cli ping
PONG

• redis password was set, but the issue persists

sudo redis-cli
127.0.0.1:6379> auth secret
OK