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Posted to common-commits@hadoop.apache.org by ji...@apache.org on 2017/09/25 23:38:44 UTC
[45/86] [abbrv] hadoop git commit: YARN-5244. Documentation required
for DNS Server implementation. Contributed by Jon Maron
YARN-5244. Documentation required for DNS Server implementation. Contributed by Jon Maron
Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo
Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/538c63ef
Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/538c63ef
Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/538c63ef
Branch: refs/heads/yarn-native-services
Commit: 538c63ef0634f197c622a4b284310768a7425ae5
Parents: 727e6d7
Author: Gour Saha <go...@apache.org>
Authored: Thu Aug 24 19:05:13 2017 -0700
Committer: Jian He <ji...@apache.org>
Committed: Mon Sep 25 16:37:22 2017 -0700
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hadoop-project/src/site/site.xml | 7 +-
.../native-services/NativeServicesDiscovery.md | 127 +++++++++++++++++++
.../native-services/NativeServicesIntro.md | 0
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.../resources/images/dns_record_creation.jpeg | Bin 0 -> 51911 bytes
.../resources/images/dns_record_removal.jpeg | Bin 0 -> 58041 bytes
6 files changed, 133 insertions(+), 1 deletion(-)
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http://git-wip-us.apache.org/repos/asf/hadoop/blob/538c63ef/hadoop-project/src/site/site.xml
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diff --git a/hadoop-project/src/site/site.xml b/hadoop-project/src/site/site.xml
index a88f0e3..e6e9d86 100644
--- a/hadoop-project/src/site/site.xml
+++ b/hadoop-project/src/site/site.xml
@@ -151,7 +151,12 @@
<item name="Timeline Server" href="hadoop-yarn/hadoop-yarn-site/TimelineServer.html#Timeline_Server_REST_API_v1"/>
<item name="Timeline Service V.2" href="hadoop-yarn/hadoop-yarn-site/TimelineServiceV2.html#Timeline_Service_v.2_REST_API"/>
</menu>
-
+
+ <menu name="YARN Native Services" inherit="top">
+ <item name="Introduction" href="hadoop-yarn/hadoop-yarn-site/native-services/NativeServicesIntro.html"/>
+ <item name="Native Services Discovery" href="hadoop-yarn/hadoop-yarn-site/native-services/NativeServicesDiscovery.html"/>
+ </menu>
+
<menu name="Hadoop Compatible File Systems" inherit="top">
<item name="Aliyun OSS" href="hadoop-aliyun/tools/hadoop-aliyun/index.html"/>
<item name="Amazon S3" href="hadoop-aws/tools/hadoop-aws/index.html"/>
http://git-wip-us.apache.org/repos/asf/hadoop/blob/538c63ef/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/native-services/NativeServicesDiscovery.md
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diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/native-services/NativeServicesDiscovery.md b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/native-services/NativeServicesDiscovery.md
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+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/native-services/NativeServicesDiscovery.md
@@ -0,0 +1,127 @@
+# YARN DNS Server
+## Introduction
+
+The YARN DNS Server provides a standard DNS interface to the information posted into the YARN Registry by deployed applications. The DNS service serves the following functions:
+
+1. **Exposing existing service discovery information via DNS** - Information provided in
+the current YARN service registry’s records will be converted into DNS entries, thus
+allowing users to discover information about YARN applications using standard DNS
+client mechanisms (for e.g. a DNS SRV Record specifying the hostname and port
+number for services).
+2. **Enabling Container to IP mappings** - Enables discovery of the IPs of containers via
+standard DNS lookups. Given the availability of the records via DNS, container
+namebased communication will be facilitated (e.g. ‘curl
+http://myContainer.myDomain.com/endpoint’).
+
+## Service Properties
+
+The existing YARN Service Registry is leveraged as the source of information for the DNS Service.
+
+The following core functions are supported by the DNS Server:
+
+###Functional properties
+
+1. Supports creation of DNS records for endpoints of the deployed YARN applications
+2. Record names remain unchanged during restart of containers and/or applications
+3. Supports reverse lookups (name based on IP).
+4. Supports security using the standards defined by The Domain Name System Security
+Extensions (DNSSEC)
+5. Highly available
+6. Scalable - The service provides the responsiveness (e.g. low latency) required to
+respond to DNS queries (timeouts yield attempts to invoke other configured name
+servers).
+
+###Deployment properties
+
+1. Supports integration with existing DNS assets (e.g. a corporate DNS server) by acting as
+a DNS server for a Hadoop cluster zone/domain. The server is not intended to act as a
+primary DNS server and does not forward requests to other servers.
+2. The DNS Server exposes a port that can receive both TCP and UDP requests per
+DNS standards. The default port for DNS protocols is in a restricted, administrative port
+range (53), so the port is configurable for deployments in which the service may
+not be managed via an administrative account.
+
+##DNS Record Name Structure
+
+The DNS names of generated records are composed from the following elements (labels). Note that these elements must be compatible with DNS conventions (see “Preferred Name Syntax” in RFC 1035):
+
+* **domain** - the name of the cluster DNS domain. This name is provided as a
+configuration property. In addition, it is this name that is configured at a parent DNS
+server as the zone name for the defined yDNS zone (the zone for which the parent DNS
+server will forward requests to yDNS). E.g. yarncluster.com
+* **username** - the name of the application deployer. This name is the simple shortname (for
+e.g. the primary component of the Kerberos principal) associated with the user launching
+the application. As the username is one of the elements of DNS names, it is expected
+that this also confirms DNS name conventions (RFC 1035 linked above) so special translation is performed for names with special characters like hyphens and spaces.
+* **application name** - the name of the deployed YARN application. This name is inferred
+from the YARN registry path to the application's node. Application name, rather thn application id, was chosen as a way of making it easy for users to refer to human-readable DNS
+names. This obviously mandates certain uniqueness properties on application names.
+* **container id** - the YARN assigned ID to a container (e.g.
+container_e3741_1454001598828_01_000004)
+* **component name** - the name assigned to the deployed component (for e.g. a master
+component). A component is a distributed element of an application or service that is
+launched in a YARN container (e.g. an HBase master). One can imagine multiple
+components within an application. A component name is not yet a first class concept in
+YARN, but is a very useful one that we are introducing here for the sake of yDNS
+entries. Many frameworks like MapReduce, Slider already have component names
+(though, as mentioned, they are not yet supported in YARN in a first class fashion).
+* **api** - the api designation for the exposed endpoint
+
+###Notes about DNS Names
+
+* In most instances, the DNS names can be easily distinguished by the number of
+elements/labels that compose the name. The cluster’s domain name is always the last
+element. After that element is parsed out, reading from right to left, the first element
+maps to the application user and so on. Wherever it is not easily distinguishable, naming conventions are used to disambiguate the name using a prefix such as
+“container” or suffix such as “api”. For example, an endpoint published as a
+management endpoint will be referenced with the name *management-api.griduser.yarncluster.com*.
+* Unique application name (per user) is not currently supported/guaranteed by YARN, but
+it is supported by frameworks such as Apache Slider. The yDNS service currently
+leverages the last element of the ZK path entry for the application as an
+application name. These application names have to be unique for a given user.
+
+##DNS Server Functionality
+
+The primary functions of the DNS service are illustrated in the following diagram:
+
+
+
+
+###DNS record creation
+The following figure illustrates at slightly greater detail the DNS record creation and registration sequence (NOTE: service record updates would follow a similar sequence of steps,
+distinguished only by the different event type):
+
+
+
+###DNS record removal
+Similarly, record removal follows a similar sequence
+
+
+
+(NOTE: The DNS Zone requires a record as an argument for the deletion method, thus
+requiring similar parsing logic to identify the specific records that should be removed).
+
+###DNS Service initialization
+* The DNS service initializes both UDP and TCP listeners on a configured port. As
+noted above, the default port of 53 is in a restricted range that is only accessible to an
+account with administrative privileges.
+* Subsequently, the DNS service listens for inbound DNS requests. Those requests are
+standard DNS requests from users or other DNS servers (for example, DNS servers that have the
+YARN DNS service configured as a forwarder).
+
+## Configuration
+The YARN DNS server reads its configuration properties from the yarnsite.xml file. The following are the DNS associated configuration properties:
+
+| Name | Description |
+| ------------ | ------------- |
+| hadoop.registry.dns.enabled | The DNS functionality is enabled for the cluster. Default is false. |
+| hadoop.registry.dns.domain-name | The domain name for Hadoop cluster associated records. |
+| hadoop.registry.dns.bind-address | Address associated with the network interface to which the DNS listener should bind. |
+| hadoop.registry.dns.bind-port | The port number for the DNS listener. The default port is 53. However, since that port falls in a administratoronly range, typical deployments may need to specify an alternate port. |
+| hadoop.registry.dns.dnssec.enabled | Indicates whether the DNSSEC support is enabled. Default is false. |
+| hadoop.registry.dns.public-key | The base64 representation of the server’s public key. Leveraged for creating the DNSKEY Record provided for DNSSEC client requests. |
+| hadoop.registry.dns.private-key-file | The path to the standard DNSSEC private key file. Must only be readable by the DNS launching identity. See [dnssec-keygen](https://ftp.isc.org/isc/bind/cur/9.9/doc/arm/man.dnssec-keygen.html) documentation. |
+| hadoop.registry.dns-ttl | The default TTL value to associate with DNS records. The default value is set to 1 (a value of 0 has undefined behavior). A typical value should be approximate to the time it takes YARN to restart a failed container. |
+| hadoop.registry.dns.zone-subnet | An indicator of the IP range associated with the cluster containers. The setting is utilized for the generation of the reverse zone name. |
+| hadoop.registry.dns.zone-mask | The network mask associated with the zone IP range. If specified, it is utilized to ascertain the IP range possible and come up with an appropriate reverse zone name. |
+| hadoop.registry.dns.zones-dir | A directory containing zone configuration files to read during zone initialization. This directory can contain zone master files named *zone-name.zone*. See [here](http://www.zytrax.com/books/dns/ch6/mydomain.html) for zone master file documentation.|
http://git-wip-us.apache.org/repos/asf/hadoop/blob/538c63ef/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/native-services/NativeServicesIntro.md
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