From b0bc7681c32c33756a6c4c77aa9257990183dee6 Mon Sep 17 00:00:00 2001 From: Wei-Chiu Chuang Date: Thu, 11 Aug 2016 12:27:09 -0700 Subject: [PATCH] HADOOP-13190. Mention LoadBalancingKMSClientProvider in KMS HA documentation. Contributed by Wei-Chiu Chuang. (cherry picked from commit db719ef125b11b01eab3353e2dc4b48992bf88d5) (cherry picked from commit 6d53e096b2d96b9aace46fa9f34cd93e7f0f22a6) --- .../hadoop-kms/src/site/markdown/index.md.vm | 60 +++++++++++++++++-- 1 file changed, 56 insertions(+), 4 deletions(-) diff --git a/hadoop-common-project/hadoop-kms/src/site/markdown/index.md.vm b/hadoop-common-project/hadoop-kms/src/site/markdown/index.md.vm index d2d1d994538..729b2b9aed8 100644 --- a/hadoop-common-project/hadoop-kms/src/site/markdown/index.md.vm +++ b/hadoop-common-project/hadoop-kms/src/site/markdown/index.md.vm @@ -19,6 +19,8 @@ Hadoop Key Management Server (KMS) - Documentation Sets ======================================================= + + Hadoop KMS is a cryptographic key management server based on Hadoop's **KeyProvider** API. It provides a client and a server components which communicate over HTTP using a REST API. @@ -34,6 +36,18 @@ KMS Client Configuration The KMS client `KeyProvider` uses the **kms** scheme, and the embedded URL must be the URL of the KMS. For example, for a KMS running on `http://localhost:16000/kms`, the KeyProvider URI is `kms://http@localhost:16000/kms`. And, for a KMS running on `https://localhost:16000/kms`, the KeyProvider URI is `kms://https@localhost:16000/kms` +The following is an example to configure HDFS NameNode as a KMS client in +`hdfs-site.xml`: + + + dfs.encryption.key.provider.uri + kms://http@localhost:9600/kms + + The KeyProvider to use when interacting with encryption keys used + when reading and writing to an encryption zone. + + + KMS --- @@ -623,13 +637,51 @@ Additionally, KMS delegation token secret manager can be configured with the fol ``` -$H3 Using Multiple Instances of KMS Behind a Load-Balancer or VIP +$H3 High Availability -KMS supports multiple KMS instances behind a load-balancer or VIP for scalability and for HA purposes. +Multiple KMS instances may be used to provide high availability and scalability. +Currently there are two approaches to supporting multiple KMS instances: +running KMS instances behind a load-balancer/VIP, +or using LoadBalancingKMSClientProvider. -When using multiple KMS instances behind a load-balancer or VIP, requests from the same user may be handled by different KMS instances. +In both approaches, KMS instances must be specially configured to work properly +as a single logical service, because requests from the same client may be +handled by different KMS instances. In particular, +Kerberos Principals Configuration, HTTP Authentication Signature and Delegation +Tokens require special attention. -KMS instances behind a load-balancer or VIP must be specially configured to work properly as a single logical service. +$H4 Behind a Load-Balancer or VIP + +Because KMS clients and servers communicate via a REST API over HTTP, +Load-balancer or VIP may be used to distribute incoming traffic to achieve +scalability and HA. In this mode, clients are unaware of multiple KMS instances +at the server-side. + +$H4 Using LoadBalancingKMSClientProvider + +An alternative to running multiple KMS instances behind a load-balancer or VIP, +is to use LoadBalancingKMSClientProvider. Using this approach, a KMS client +(for example, a HDFS NameNode) is aware of multiple KMS instances, and it sends +requests to them in a round-robin fashion. LoadBalancingKMSClientProvider is +implicitly used when more than one URI is specified in +`dfs.encryption.key.provider.uri`. + +The following example in `hdfs-site.xml` configures two KMS +instances, `kms01.example.com` and `kms02.example.com`. +The hostnames are separated by semi-colons, and all KMS instances must run +on the same port. + + + dfs.encryption.key.provider.uri + kms://https@kms01.example.com;kms02.example.com:9600/kms + + The KeyProvider to use when interacting with encryption keys used + when reading and writing to an encryption zone. + + + +If a request to a KMS instance fails, clients retry with the next instance. The +request is returned as failure only if all instances fail. $H4 HTTP Kerberos Principals Configuration