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crazylion lee

Bcfg2 - 0 views

bcfg2.org

sysadmin server system

shared by crazylion lee on 08 Oct 16 - No Cached
  • crazylion lee on 08 Oct 16
     
    "Bcfg2 helps system administrators produce a consistent, reproducible, and verifiable description of their environment, and offers visualization and reporting tools to aid in day-to-day administrative tasks. It is the fifth generation of configuration management tools developed in the Mathematics and Computer Science Division of Argonne National Laboratory. "
張 旭

Controllers | Kubernetes - 0 views

kubernetes.io/...controller

kubernetes system auto

shared by 張 旭 on 14 May 21 - No Cached
  • In robotics and automation, a control loop is a non-terminating loop that regulates the state of a system.
  • controllers are control loops that watch the state of your cluster, then make or request changes where needed
  • Each controller tries to move the current cluster state closer to the desired state.
  • ...12 more annotations...
  • A controller tracks at least one Kubernetes resource type.
  • The controller(s) for that resource are responsible for making the current state come closer to that desired state.
  • in Kubernetes, a controller will send messages to the API server that have useful side effects.
  • Built-in controllers manage state by interacting with the cluster API server.
  • By contrast with Job, some controllers need to make changes to things outside of your cluster.
  • the controller makes some change to bring about your desired state, and then reports current state back to your cluster's API server. Other control loops can observe that reported data and take their own actions.
  • As long as the controllers for your cluster are running and able to make useful changes, it doesn't matter if the overall state is stable or not.
  • Kubernetes uses lots of controllers that each manage a particular aspect of cluster state.
  • a particular control loop (controller) uses one kind of resource as its desired state, and has a different kind of resource that it manages to make that desired state happen.
  • There can be several controllers that create or update the same kind of object.
  • you can have Deployments and Jobs; these both create Pods. The Job controller does not delete the Pods that your Deployment created, because there is information (labels) the controllers can use to tell those Pods apart.
  • Kubernetes comes with a set of built-in controllers that run inside the kube-controller-manager.
  • 張 旭 on 14 May 21
     
    "In robotics and automation, a control loop is a non-terminating loop that regulates the state of a system. "
張 旭

Monitor Node Health | Kubernetes - 0 views

kubernetes.io/...monitor-node-health

kubernetes monitor system

shared by 張 旭 on 21 Jul 21 - No Cached
  • Node Problem Detector is a daemon for monitoring and reporting about a node's health
  • Node Problem Detector collects information about node problems from various daemons and reports these conditions to the API server as NodeCondition and Event.
  • Node Problem Detector only supports file based kernel log. Log tools such as journald are not supported.
  • ...2 more annotations...
  • kubectl provides the most flexible management of Node Problem Detector.
  • run the Node Problem Detector in your cluster to monitor node health.
張 旭

How to Report Bugs Effectively - 0 views

www.chiark.greenend.org.uk/...bugs-tw.html

bug debug

shared by 張 旭 on 04 Dec 14 - Cached
  • 有個理由可以解釋為什麼技術支援工作這麼難做, 原因就是這些亂七八糟的錯誤報告
  • 希望全世界的人在報告任何錯誤前都能讀讀這篇短文
  • 錯誤報告的目的是要讓程式師能親眼目睹程式出錯
  • ...26 more annotations...
  • 如果他們無法重現問題, 就只能要你幫他們收集資訊
  • 必須要把真實發生的事實(我在電腦前看到這個狀況)和臆測(我認為問題可能是)很明顯的區分開來. 必要時可以把臆測略過不提, 不過事實絕對不能漏.
  • 資訊過多往往好過資訊不足
  • 報告錯誤的最佳方法之一就是直接示範給程式師看. 讓他們站到你的電腦前面, 執行他們的軟體, 然後指出問題所在
  • 可能會要你說明整個操作過程, 以便他們能自己重複重現問題
  • 也可能會改變操作過程多試幾次, 看看問題只在某一種狀況發生, 還是在相關的多種狀況下都有出現
  • 可能得坐下來花上幾個小時拿出整組開發工具真正深入調查
  • 最重要的還是讓程式師看到電腦出錯. 只要他們能看到問題發生, 通常都可以由此開始嘗試修正問題
  • 向一個不可能到你身旁的程式師報告錯誤, 首要目標是讓他們能重現問題. 希望讓程式師執行自己的那份程式, 進行相同的操作, 然後以相同的方式出錯.
  • 如果這是個有圖形介面的程式, 告訴他們你按了哪些按鈕以及按各按鈕的次序.
  • 如果是輸入命令執行的程式, 就要精確地告知你所輸入的命令
  • 在目前這個階段, 程式師只是想找出問題所在, 並不會嘗試去修正問題. 他們必須知道什麼地方出錯, 而那些錯誤訊息正是電腦對問題的最佳敘述
  • 不過如果不能同時報告錯誤訊息的內容, 光說程式出錯是沒有意義的
  • 程式師喜歡那些能重複產生的問題. 這時候快樂的程式師能更快更有效率地修正問題.
  • 並不是程式師以外的人才會寫出爛錯誤報告
  • 對程式師也一樣. 提供你自己的診斷有時可能有幫助, 不過一定要先敘述症狀. 診斷是可有可無的, 絕不能取代症狀敘述
  • 用你的聰明智慧幫助程式師是很好. 即使你的推論不對, 程式師也應該心存感謝, 因為至少你已經試著讓他們更好過. 不過記得要報告症狀, 否則你可能會讓他們過得更痛苦
  • 程式師要確認他們處理的是真正的偶發性問題還是與機器相關的錯誤. 他們會要知道很多有關你的電腦的細節
  • 很多報告來自非英語系地區, 而且很多人為英文寫得不好致歉. 通常有為英文不好而致歉的錯誤報告實際上都非常清楚有用
  • 寧願多給資訊而不要少給
  • 閱讀你寫的東西
  • 自己把報告重新讀一遍, 看看有是否夠清楚. 如果你有寫出了重現問題的步驟列表, 試著照做一遍確定沒有漏掉任何步驟.
    • 張 旭
      張 旭 on 04 Dec 14
       
      自己的報告自己看
  • 一份錯誤報告的首要目標是要讓程式師親眼看到問題
  • 如果你不能到他們面前把問題顯示出來, 就得提供詳細的指示讓他們能自己做出來
  • 如果你自認能力夠的話可以儘量嘗試自己診斷問題, 不過即使你做了診斷, 還是應該報告問題的症狀
張 旭

What exactly was the point of [ "x$var" = "xval" ]? - Vidar's Blog - 0 views

www.vidarholen.net/...blog

shell programming code

shared by 張 旭 on 21 Apr 21 - No Cached
  • x-hack
  • test "x$arg" = "x-f"
  • the utility used a simple recursive descent parser without backtracking, which gave unary operators precedence over binary operators and ignored trailing arguments.
  • ...3 more annotations...
  • The x-hack is effective because no unary operators can start with x.
  • the x-hack could be used to work around certain bugs all the way up until 2015, seven years after StackOverflow wrote it off as an archaic relic of the past!
  • The Dash issue of [ "(" = ")" ] was originally reported in a form that affected both Bash 3.2.48 and Dash 0.5.4 in 2008. You can still see this on macOS bash today
  • 張 旭 on 21 Apr 21
     
    "x$var"
張 旭

Improving Kubernetes reliability: quicker detection of a Node down | Fatal failure - 0 views

fatalfailure.wordpress.com/...icker-detection-of-a-node-down

kubernetes HA

shared by 張 旭 on 21 Jul 21 - No Cached
  • when a Node gets down, the pods of the broken node are still running for some time and they still get requests, and those requests, will fail.
  • 1- The Kubelet posts its status to the masters using –node-status-update-frequency=10s 2- A node dies 3- The kube controller manager is the one monitoring the nodes, using –-node-monitor-period=5s it checks, in the masters, the node status reported by the Kubelet. 4- Kube controller manager will see the node is unresponsive, and has this grace period –node-monitor-grace-period=40s until it considers the node unhealthy.
  • node-status-update-frequency x (N-1) != node-monitor-grace-period
  • ...2 more annotations...
  • 5- Once the node is marked as unhealthy, the kube controller manager will remove its pods based on –pod-eviction-timeout=5m0s
  • 6- Kube proxy has a watcher over the API, so the very first moment the pods are evicted the proxy will notice and update the iptables of the node, removing the endpoints from the services so the failing pods won’t be accessible anymore.
張 旭

Tagging AWS resources - AWS General Reference - 0 views

docs.aws.amazon.com/...aws_tagging.html

aws cloud

shared by 張 旭 on 20 Jan 22 - No Cached
  • assign metadata to your AWS resources in the form of tags.
  • a user-defined key and value
  • Tag keys are case sensitive.
  • ...17 more annotations...
  • tag values are case sensitive.
  • Tags are accessible to many AWS services, including billing.
  • personally identifiable information (PII)
  • apply it consistently across all resource types.
  • Use automated tools to help manage resource tags.
  • Use too many tags rather than too few tags.
  • Tag policies let you specify tagging rules that define valid key names and the values that are valid for each key.
  • Name – Identify individual resources
  • Environment – Distinguish between development, test, and production resources
  • Project – Identify projects that the resource supports
  • Owner – Identify who is responsible for the resource
  • Each resource can have a maximum of 50 user created tags.
  • For each resource, each tag key must be unique, and each tag key can have only one value.
  • Tag keys and values are case sensitive.
  • decide on a strategy for capitalizing tags, and consistently implement that strategy across all resource types.
  • AWS Cost Explorer and detailed billing reports let you break down AWS costs by tag.
  • An effective tagging strategy uses standardized tags and applies them consistently and programmatically across AWS resources.
  • 張 旭 on 20 Jan 22
     
    "assign metadata to your AWS resources in the form of tags."
張 旭

Installing Addons | Kubernetes - 0 views

kubernetes.io/...addons

kubernetes network networking

shared by 張 旭 on 25 Jan 23 - No Cached
  • Calico is a networking and network policy provider. Calico supports a flexible set of networking options so you can choose the most efficient option for your situation, including non-overlay and overlay networks, with or without BGP. Calico uses the same engine to enforce network policy for hosts, pods, and (if using Istio & Envoy) applications at the service mesh layer.
  • Cilium is a networking, observability, and security solution with an eBPF-based data plane. Cilium provides a simple flat Layer 3 network with the ability to span multiple clusters in either a native routing or overlay/encapsulation mode, and can enforce network policies on L3-L7 using an identity-based security model that is decoupled from network addressing. Cilium can act as a replacement for kube-proxy; it also offers additional, opt-in observability and security features.
  • CoreDNS is a flexible, extensible DNS server which can be installed as the in-cluster DNS for pods.
  • ...1 more annotation...
  • The node problem detector runs on Linux nodes and reports system issues as either Events or Node conditions.
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