SUYEON LEE created HDFS-17790:
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Summary: Support pattern matching for YARN proxy addresses.
Key: HDFS-17790
URL: https://issues.apache.org/jira/browse/HDFS-17790
Project: Hadoop HDFS
Issue Type: Bug
Components: router
Affects Versions: 3.4.1
Reporter: SUYEON LEE
Attachments: 스크린샷 2025-02-20 오후 6.14.27.png
*Issue:*
In a YARN Federation environment utilizing multiple YARN Routers, if a Global
Server Load Balancer (GSLB) is used for distributing requests to these Routers
_without_ sticky session support, users encounter redirection errors.
!스크린샷 2025-02-20 오후 6.14.27.png!
These errors typically manifest when accessing application UIs or logs via the
NodeManager's proxy.
*Problem Details:*
The root cause of this issue lies in how the NodeManager (NM) resolves the YARN
Router address for proxying web requests. The NodeManager uses the
{{yarn.web-proxy.address}} configuration property to determine the Router's
address. However, this property is designed to accommodate only a single
hostname or IP address.
When a GSLB without sticky sessions distributes requests, an initial request
might be routed to Router A, while a subsequent request (e.g., for application
logs, proxied by an NM) might be directed by the GSLB to Router B, or the NM
might be configured with a specific Router/GSLB VIP that resolves to Router B.
If the ApplicationMaster (AM) for the application in question is registered
with Router A, Router B may not be able to correctly proxy or redirect the
request, leading to errors. The NM's attempt to proxy through an "incorrect" or
context-unaware Router (relative to where the AM is known) due to the
single-host limitation in {{yarn.web-proxy.address}} results in these failures.
*Analysis / Root Cause Summary:*
# *Environment:* YARN Federation with multiple YARN Routers.
# *Load Balancing:* GSLB used without sticky session support, leading to
requests for the same session potentially hitting different Routers.
# *NM Proxy Mechanism:* NodeManagers use {{yarn.web-proxy.address}} to
identify the YARN Router for proxying UI/log requests.
# *Configuration Limitation:* {{yarn.web-proxy.address}} supports only a
single host, making it incompatible with a multi-Router setup where requests
are not sticky.
# *Symptom:* Redirection errors occur as the NM may attempt to proxy through a
Router that does not have the necessary context for the specific
application/AM, or is not the Router the user was initially interacting with
via the GSLB.
*Proposed Solution:*
To address this limitation, a patch has been developed to introduce
*pattern-based address matching for the YARN web proxy functionality.*
This enhancement will allow {{yarn.web-proxy.address.pattern}} to be configured
with a pattern or a list of Routers. The NodeManager's proxy mechanism can then
intelligently select or match the appropriate Router address, ensuring that
requests are proxied correctly even in a federated environment with multiple
Routers and non-sticky load balancing.
*Goal of the Patch:*
* Enable robust YARN web proxying in federated environments with multiple
Routers load-balanced by a non-sticky GSLB.
* Improve the usability and reliability of accessing application UIs and logs
in such configurations.
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