早前,GitHub 发布 GitHub Actions 项目,开发者可通过 GitHub Actions 存储和搜索代码,部分代码可直接运行。本文尝试使用 AWS Lambda 和 API Gateway 作为基本 API,编写应用程序原型并用名为 gourmet 的容器运行函数,虽然这可能不会让代码易于管理,但至少不需要写 API 或者 Web 应用程序。
正如 Lambda 函数在 AWS 中运行一样,Github Actions 是一种强大的管理方式,可直接扩展应用。使用 AWS Lambda,可将代码挂接到几乎任何事件上,比如 EC2 创建、终止、DNS 记录更改等,不需要运行服务器,只需加载代码就能正常工作。
本文作者针对此做了一些尝试,但需要 CI 服务器。为了拥有可测试的 kubernetes 集群,作者自建私有存储库,目前因内部有些混乱暂不准备开源。
无论如何,以下是项目文件夹:
├── .github
│ ├── actions
│ │ ├── deploy
│ │ │ ├── deploy
│ │ │ └── Dockerfile
│ │ └── dryrun
│ │ ├── Dockerfile
│ │ └── dryrun
│ └── main.workflow
└── kubernetes
├── digitalocean.yaml
├── external-dns.yaml
├── micro.yaml
├── namespaces.yaml
├── nginx.yaml
└── openvpn.yaml
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kubernetes 目录包含集群安装的所有东西。对于此存储库的每次新推送,需要检查是否可用命令 kubectl apply -f./kubernetes --dryrun 将其应用于 kubernetes 集群,并且当合并 PR 时,应用更改。
因此,作者在.github/main.workflow 中创办了工作流:
## Workflow defines what we want to call a set of actions.
## For every new push check if the changes can be applied to kubernetes ## using the action called: kubectl dryrun
workflow "after a push check if they apply to kubernetes" {
on = "push"
resolves = ["kubectl dryrun"]
}
## When a PR is merged trigger the action: kubectl deploy. To apply the new code to master.
workflow "on merge to master deploy on kubernetes" {
on = "pull_request"
resolves = ["kubectl deploy"]
}
## This is the action that checks if the push can be applied to kubernetes
action "kubectl dryrun" {
uses = "./.github/actions/dryrun"
secrets = ["KUBECONFIG"]
}
## This is the action that applies the change to kubernetes
action "kubectl deploy" {
uses = "./.github/actions/deploy"
secrets = ["KUBECONFIG"]
}
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secrets 是一组环境变量,可从外部设置值。如果帐户启用 GitHub Action,则每个存储库的 Setting 都会有一个名为 secrets 的新标签。
本例,作者将 KUBECONFIG 设置为 kubeconfig 文件的 base64,允许 GitHub Action 授权给 Kubernetes 集群。
两个操作类似,第一个操作位于 .github/actions/dryrun 目录:
├── .github
├── actions
└── dryrun
├── Dockerfile
└── dryrun
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包含一个 Dockerfile
FROM alpine:latest
## The action name displayed by GitHub
LABEL "com.github.actions.name"="kubectl dryrun"
## The description for the action
LABEL "com.github.actions.description"="Check the kubernetes change to apply."
## https://developer.github.com/actions/creating-github-actions/creating-a-docker-container/#supported-feather-icons
LABEL "com.github.actions.icon"="check"
## The color of the action icon
LABEL "com.github.actions.color"="blue"
RUN apk add --no-cache \
bash \
ca-certificates \
curl \
git \
jq
RUN curl -L -o /usr/bin/kubectl https://storage.googleapis.com/kubernetes-release/release/v1.13.0/bin/linux/amd64/kubectl && \
chmod +x /usr/bin/kubectl && \
kubectl version --client
COPY dryrun /usr/bin/dryrun
CMD ["dryrun"]
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如上所示,只需要一个 Dockerfile,工作原理和 docker 类似。Cmd dryrun 在这里是复制的 bash 脚本:
#!/bin/bash
main(){
echo ">>>> Action started"
# Decode the secret passed by the action and paste the config in a file.
echo $KUBECONFIG | base64 -d > ./kubeconfig.yaml
echo ">>>> kubeconfig created"
# Check if the kubernetes directory has change
diff=$(git diff --exit-code HEAD~1 HEAD ./kubernetes)
if [ $? -eq 1 ]; then
echo ">>>> Detected a change inside the kubernetes directory"
# Apply the changes with --dryrun just to validate them
kubectl apply --kubeconfig ./kubeconfig.yaml --dry-run -f ./kubernetes
else
echo ">>>> No changed detected inside the ./kubernetes folder. Nothing to do."
fi
}
main "$@"
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第二个操作和此几乎一样,Dockerfile 是相同的,但 CMD 看起来是这样的:
#!/bin/bash
main(){
# Decode the secret passed by the action and paste the config in a file.
echo $KUBECONFIG | base64 -d > ./kubeconfig.yaml
# Check if it is an event generated by the PR is a merge
merged=$(jq --raw-output .pull_request.merged "$GITHUB_EVENT_PATH")
# Retrieve the base branch for the PR because I would like to apply only PR merged to master
baseRef=$(jq --raw-output .pull_request.base.ref "$GITHUB_EVENT_PATH")
if [[ "$merged" == "true" ]] && [[ "$baseRef" == "master" ]]; then
echo ">>>> PR merged into master. Shipping to k8s!"
kubectl apply --kubeconfig ./kubeconfig.yaml -f ./kubernetes
else
echo ">>>> Nothing to do here!"
fi
}
main "$@"
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除此之外,工作流文件还有一个生成器,似乎效果不错。secrets 允许开箱即用,并与第三方服务集成,也可用 bash 做任何想做的事情!
参考链接:https://gianarb.it/blog/kubernetes-github-action
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