rancher-metadata

A simple HTTP server that returns EC2-style metadata information that varies depending on the source IP address making the request. This package contains no Rancher-specific code, but is used in Rancher with an answer file that provide the requesting container information about itself, the service and stack it is a member of, the host it is running on, etc.

Usage

  rancher-metadata --answers /path/to/answers.{yaml|json} [--debug] [--listen [host]:port] [--log path] [--pid-file path] [--xff]

Compile

  godep go build

CLI Options

Option	Default	Description
--answers	./answers.yaml	Path to a JSON or YAML file with client-specific answers
--debug	off	Log more debugging info
--listen	0.0.0.0:80	IP address and port to listen on
--log	none	Output log info to a file path instead of stdout
--pid-file	none	Write the server PID to a file path on startup
--xff	off	Enable using the X-Forwarded-For header to determine source IP

Answers File

The answers file provides all the structure that the metadata server responds with.

• The top-level must be a map of version numbers, where each version should be an ISO-8601 date (yyyy-mm-dd) for compatibility with Rancher/Amazon EC2-style.
  • There may be an additional version called latest which should be the same as one of the dated version. If one is not provided, the highest version ASCII-betically will be used as latest.
• The 2nd level (top level of each version) must be a map of client IP addresses. The request IP will be used to look up the appropriate set of answers.
  • A special key default will be checked if no answer is found in a client IP-specific entry.

YAML

'2015-12-19': &latest
  '10.1.2.2':
    key1: value1
    arbitrarily:
      nested:
        - YAML
        - of
        - any
        - type
        - 42
        - null
        - false
  '192.168.0.2':
    key1: value2

  # "default" is a special key that will be checked if no answer is found in a client IP-specific entry
  default:
    key1: value3

'2015-07-25':
  # Data for older revision

latest: *latest

JSON

{
  "2015-12-19": {
    "10.1.2.2": {
      "key1": "value1",
      "arbitrarily": {
        "nested": [
          "JSON", "of", "any", "type", 42, null, false
        ]
      }
    },

    "192.168.0.2": {
      "key1": "value2"
    },

    # "default" is a special key that will be checked if no answer is found in a client IP-specific entry
    "default": {
      "key1": "value3"
    }
  },

  "2015-07-25": {
    # Data for older revision
  },
}

Answering queries

A query is answered by following the pieces of the path to walk the answers for the requested IP one step at a time. If the key in the first section of the path is not found or there is no answers entry for the request IP, the "default" section is checked. Defaults are not checked if there are client-specific answers they match one (or more) levels of the path.

If the request contains an Accept header requesting application/json, the response will be the matching subtree as a JSON document.

If the request contains an Accept header requesting {application|text}/{yaml|x-yaml}, the response will be the matching subtree as a YAML document.

Contact

For bugs, questions, comments, corrections, suggestions, etc., open an issue in rancher/rancher with a title starting with [rancher-metadata] .

Or just click here to create a new issue.

License

Copyright (c) 2015-2016 Rancher Labs, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.