網路原理 綜合上述，由於 kube-proxy 的作用，在 Service 的呼叫過程中用戶端無須關心後端 有幾個 Pod，中間過程的通訊、負載平衡及故障恢復都是透明的，如圖 2.29 所示。 服務路由訊息透過 watch API Server 取得 透過 iptables 的 DNAT 傳送到 kube-proxy 外部 Client 叢集自動分派服務 的 IP 圖 2.29 Service 程式內部的一種資料結構， 2-96 Kubernetes 核心原理 2 目前已經有多個開源元件支援這個網路模型。這裡將介紹幾個常見的模型，分別是 Flannel、Open vSwitch 及直接路由的方式。 1. Flannel Flannel 之所以可以建置 Kubernetes 依賴的底層網路，是因為它能實現以下兩點： (1) 它能協助 Kubernetes，給每一個 Node 上的 的加入是非常簡單的。可以在 Node 節點 上安裝 Docker、Kubelet 和 kube-proxy 服務，然後將 Kubelet 和 kube-proxy 的啟動 參數中的 Master URL 指定為目前 Kubernetes 叢集 Master 的位址，最後啟動這些服 務。基於 Kubelet 的自動註冊機制，新的 Node 將會自動加入現有的 Kubernetes 叢 集中，如圖

t; use reqwest::Url; use scraper::{Html, Selector}; use thiserror::Error; enum Error { ReqwestError(#[from] reqwest::Error), BadResponse(String), } struct CrawlCommand { url: Url, extract_links: bool visit_page(client: &Client, command: &CrawlCommand) -> ResultUrl>, Error> { println!("Checking {:#}", command.url); let response = client.get(command.url.clone()).send()?; if !response.status().is_success() { mut link_urls = Vec::new(); if !command.extract_links { return Ok(link_urls); } let base_url = response.url().to_owned(); let body_text = response.text()?; let document = Html::parse_document(&body_text);

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – instead. source Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – instead. source Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – instead. source Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – instead. source Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – instead. source Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – FILESYSTEM 1203 Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – FILESYSTEM 1201 Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified

by package actions which change the manifest. See Pkg.precompile. JULIA_PKG_SERVER Specifies the URL of the package registry to use. By default, Pkg uses https://pkg.julialang.org to fetch Julia packages ExponentialBackOff(n=3, first_delay=5, max_delay=1000)) retry(http_get, check=(s,e)->e.status == "503")(url) retry(read, check=(s,e)->isa(e, IOError))(io, 128; all=false) source Base.ExponentialBackOff – FILESYSTEM 1200 Base.download – Function. download(url::AbstractString, [path::AbstractString = tempname()]) -> path Download a file from the given url, saving it to the location path, or if not specified