POST with curl hangs unless you disable expect 100 continue via -H 'Expect:'

[codefromthecrypt]

The same POST command I use for a local zipkin hangs for the one here in docker, unless I add -H 'Expect:'. I'm not sure why.. anyone have ideas?

Ex this works, but only if I add -H 'Expect:'

$ curl -vs 192.168.99.100:9411/api/v1/spans -H'Content-type: application/json' -H 'Expect:' -d '[
  {
    "traceId": "5e1b76cb257aa6fd",
    "name": "app - root span",
    "id": "168ba9a2869c3ae1",
    "timestamp": 1473066067938000,
    "duration": 484655,
    "annotations": [
      {
        "timestamp": 1473066067938000,
        "value": "sr",
        "endpoint": {
          "serviceName": "app",
          "ipv4": "0.0.0.0"
        }
      },
      {
        "timestamp": 1473066068422655,
        "value": "ss",
        "endpoint": {
          "serviceName": "app",
          "ipv4": "0.0.0.0"
        }
      }
    ],
    "binaryAnnotations": []
  },
  {
    "traceId": "5e1b76cb257aa6fd",
    "name": "app test - get",
    "id": "fbbff4adc94c01cb",
    "parentId": "168ba9a2869c3ae1",
    "timestamp": 1473066067939000,
    "duration": 483823,
    "annotations": [],
    "binaryAnnotations": [
      {
        "key": "error",
        "value": "org.sql2o.Sql2oException: Database error: ORA-00942: table or view does not exist\n",
        "endpoint": {
          "serviceName": "app",
          "ipv4": "0.0.0.0"
        }
      },
      {
        "key": "lc",
        "value": "Application",
        "endpoint": {
          "serviceName": "app",
          "ipv4": "0.0.0.0"
        }
      }
    ]
  }
]'
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (127.0.0.1) port 9411 (#0)
> POST /api/v1/spans HTTP/1.1
> Host: 192.168.99.100:9411
> User-Agent: curl/7.43.0
> Accept: */*
> Content-type: application/json
> Content-Length: 1216
> 
* upload completely sent off: 1216 out of 1216 bytes
< HTTP/1.1 202 
< X-Application-Context: zipkin-server:9411
< Content-Length: 0
< Date: Fri, 09 Sep 2016 01:52:28 GMT
< 
* Connection #0 to host 192.168.99.100 left intact

[codefromthecrypt]

cool link from @mansu https://support.urbanairship.com/hc/en-us/articles/213492003--Expect-100-Continue-Issues-and-Risks