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RackHD Debugging and Isolation

RackHD Debugging and Isolation

Overview of RackHD for the purposes of assisting with debugging and isolation of unexpected results...

Joseph Heck

April 26, 2016
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  1. RackHD
    Debugging and Isola3on

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  2. Taking Data to Informa3on
    •  Analysis is cri3cal to resolving defects
    •  So=ware QA can go much deeper
    – All the code is available to inves3gate
    – Architecture is open
    – Responsibili3es for components well defined
    •  A roadmap to learn never hurts…
    And that is what this deck includes...

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  3. Isola3on
    •  Break down the problem into smaller parts
    •  Look for the natural boundaries in the system
    •  Implies you need to know how it is built, how
    it interacts
    – Reasoning about components
    •  But what if you don’t know?
    – Or can’t remember?

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  4. Scien3fic Method
    •  How to learn what it really does
    –  The docs lie, programmers make mistakes, and there’s
    always unintended consequences
    •  Scien3fic Method Process
    –  Ask a ques3on
    –  Do the background research
    –  Construct a hypothesis
    –  Test you hypothesis
    –  Analyze your data, draw a conclusion
    –  Communicate your results

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  5. Exis3ng tests
    •  Integra3on Tests
    –  hRps://github.com/RackHD/RackHD/tree/master/test
    •  Unit tests for smaller so=ware components
    –  hRps://coveralls.io/github/RackHD/on-core
    –  hRps://coveralls.io/github/RackHD/on-dhcp-proxy
    –  hRps://coveralls.io/github/RackHD/on-hRp
    –  hRps://coveralls.io/github/RackHD/on-syslog
    –  hRps://coveralls.io/github/RackHD/on-taskgraph
    –  hRps://coveralls.io/github/RackHD/on-tasks
    –  hRps://coveralls.io/github/RackHD/on-Wtp
    •  hRp://rackhd.readthedocs.org/en/latest/repositories.html#repositories-status

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  6. The Background Research
    •  RackHD logical architecture
    •  Core Concepts
    – PXE Boo3ng – how it works
    – Workflow Engine Interac3ons
    – PXE boo3ng a Microkernel to extend reach
    – Profiles and Templates
    •  Configura3on and Logs

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  7. Process/Communica3ons Architecture
    hRp://rackhd.readthedocs.org/en/latest/so=ware_architecture.html#major-components

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  8. Logical Architecture
    on-syslog on-Wtp ISC dhcp
    on-dhcp-proxy
    on-hRp
    rabbitmq
    mongodb
    on-taskgraph
    SNMP IPMI AMT REDFISH … clients
    Incoming
    Events
    Workflow Engine
    Outgoing
    Ac3ons

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  9. Configura3on and Logs
    on-*
    process
    hRps://github.com/RackHD/on-core/blob/master/lib/services/configura3on.js
    hRps://github.com/RackHD/on-core/blob/fea46c/lib/common/messenger.js#L85
    Configura3on by key – Order of Precedence:
    •  Command-line argument
    •  Environment Variable
    •  Configura3on File
    •  /opt/monorail/config.json
    •  /opt/onrack/etc/monorail.json
    •  In-code defaults
    •  uri = configura3on.get(‘amqp’, ‘amqp://localhost’)
    •  Distributed in code where used/needed
    stdout
    upstart
    docker
    systemD
    /var/log/upstart/on-*
    docker logs {docker_id}
    journctl

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  10. Basic DHCP, no Proxy
    from hRp://download.intel.com/design/archives/wfm/downloads/pxespec.pdf

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  11. DHCP w/ local Proxy
    from hRp://download.intel.com/design/archives/wfm/downloads/pxespec.pdf

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  12. DHCP w/ remote Proxy
    from hRp://download.intel.com/design/archives/wfm/downloads/pxespec.pdf

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  13. PXE (addi3onal reading)
    RackHD overview descrip3on
    •  hRp://rackhd.readthedocs.org/en/latest/how_it_works.html
    PXE: what it is, how it works
    •  hRps://en.m.wikipedia.org/wiki/Preboot_Execu3on_Environment
    The PXE Spec:
    •  hRp://download.intel.com/design/archives/wfm/downloads/pxespec.pdf
    DHCP
    •  hRps://en.wikipedia.org/wiki/Dynamic_Host_Configura3on_Protocol
    DHCP Proxy
    •  hRp://www.juniper.net/documenta3on/en_US/junos13.3/topics/concept/dhcp-
    extended-dhcp-relay-proxy-overview.html

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  14. iPXE follow on
    iPXE request for a script “profiles” API
    Response:
    •  Don’t know the node: Discover it
    •  Known node, no Workflow: No-op or
    default response
    •  Known node, workflow: response
    from workflow
    client
    system
    RackHD
    hRp://rackhd.readthedocs.org/en/latest/devguide/index.html#rackhd-debugging-guide

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  15. What is a workflow
    Graph
    Task
    Task Job
    Job
    Task Task Job
    Job
    Task Job
    Graph
    •  JSON document
    •  Describes flow of execu3on
    •  Wrapper for Shared op3ons and context values
    Task
    •  JSON Data only
    •  1:1 ra3o of tasks to jobs
    •  Can have 0-n tasks as run dependencies in a graph
    •  Target nodes or arbitrary code execu3on
    Job
    •  NodeJS code backing the Task declara3on
    •  Simply a class with a run func3on
    •  Configura3on comes from Task JSON

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  16. Task Flow
    Example w/
    Failure Handling
    Task-B
    Success
    Task-D
    Task-C
    Task-A
    succeeded
    finished
    failed

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  17. Workflow Tasks
    •  Run commands, tooling
    –  IPMI
    –  SNMP
    –  RACADM
    •  Interact with RackHD data
    –  Read catalog data
    –  Set catalog values, node values
    •  Provide responses for PXE
    –  DHCP
    –  TFTP
    –  HTTP

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  18. Profiles and Templates
    workflow
    HTTP
    GET /api/1.1/profiles
    GET /api/1.1/templates/{id}
    hRps://github.com/RackHD/on-hRp/blob/master/lib/api/1.1/southbound/profiles.js
    hRps://github.com/RackHD/on-hRp/blob/master/lib/api/1.1/southbound/templates.js
    iPXE
    bootloader
    Any
    “southward”
    ini3ated
    HTTP request
    Profile == iPXE Script
    Template == Any generalized template
    hRps://github.com/RackHD/on-hRp/tree/master/data/profiles
    hRps://github.com/RackHD/on-hRp/tree/master/data/templates
    Rendered as EJS template with context from ac3ve workflow related to the node

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  19. remote host
    microkernel
    Microkernel Tasks
    workflow
    task
    runner
    HTTP
    Job.Linux.Commands
    GET /api/1.1/tasks/bootstrap.js
    (1)
    (2) start
    task
    runner
    (3) GET /api/1.1/tasks/{id}
    (4)
    (5)
    POST/api/1.1/tasks/{id}
    hRps://github.com/RackHD/on-hRp/blob/master/lib/api/1.1/southbound/tasks.js
    Job.Linux.Bootstrap
    Job.WinPE.Bootstrap
    (0)

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