如何利用 Google 开源工具 Ko 在 kubernetes 上构建并部署 Go 应用

Ko 是 Google 开源的一款用于构建并部署 Go 应用的工具。

这是一款简单、快速的 Go 应用镜像构建器。并与 Kubernetes 集成，能够将应用快速部署到 Kubernetes 上。是云原生时代 Kubernetes 应用开发的一大利器。

特点：

• 需要构建的 Go 应用对系统镜像无太多依赖（例如，无 cgo，无 OS 软件包依赖关系），最好是只有一个 go 二进制。
• 构建镜像的过程不需要 Docker ，因此可以用在轻量化的 CI/CD 场景。
• 支持 yaml 模板，可以直接用于部署 Kubernetes 应用。

如何使用

官方地址在这 https://github.com/google/ko

1. 安装 ko

此处安装的是 v0.8.2 版本的 linux x86 版本，可以根据需要自行选择版本下载

Release 地址: https://github.com/google/ko/releases

手动安装

curl -L https://github.com/google/ko/releases/download/v0.8.2/ko_0.8.2_Linux_x86_64.tar.gz | tar xzf - ko
chmod +x ./ko
sudo mv ko /usr/local/bin

brew 安装

brew install ko

go install 安装

go install github.com/google/ko

2. 镜像仓库的认证

Ko 依赖的是 Docker 的镜像仓库的认证（ Docker config 文件），即 ~/.docker/config.json

cat ~/.docker/config.json
{
	"auths": {
		"https://index.docker.io/v1/": {},
	},
	"HttpHeaders": {
		"User-Agent": "Docker-Client/19.03.13 (darwin)"
	},
	"credsStore": "desktop",
	"experimental": "disabled",
	"stackOrchestrator": "swarm"
}

如果镜像仓库没有登录过，需要先进行 Docker login 生成 对应的认证配置文件，比如我直接用的是 docker hub ,那么直接 docker login 即可。

3. 设置私有仓库的地址

Ko 通过 环境变量 KO_DOCKER_REPO 配置私有仓库的地址, 这决定了 Ko 会将编译好的镜像推到哪个仓库。

 # 这是我的 dockerhub 账号，
 # 这里也可以设置为 docker.io/zhaojizhuang66,不过 docker 会省略掉
export KO_DOCKER_REPO = zhaojizhuang66

4. 镜像构建 Ko publish

首先代码一定要在本地的 Go path 中，可以下载示例代码 https://github.com/zhaojizhuang/http-helloworld

mkdir -p $GOPATH/src/github.com
cd $GOPATH/src/github.com
git clone  https://github.com/zhaojizhuang/http-helloworld

Ko publish 构建镜像，执行命令 ko publish github.com/http-helloworld/cmd/helloworld (main函数所在的 GoPath 路径)。

$ ko publish github.com/http-helloworld/cmd/helloworld

2021/04/23 17:57:41 Using base gcr.io/distroless/static:nonroot for github.com/http-helloworld/cmd/helloworld
2021/04/23 17:57:41 No matching credentials were found for "gcr.io/distroless/static", falling back on anonymous
2021/04/23 17:57:45 Building github.com/http-helloworld/cmd/helloworld for linux/amd64
2021/04/23 17:57:46 Publishing zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest
2021/04/23 17:57:52 pushed blob: sha256:a3e2b18c53ecc2aab65b3b70e5c16486e48f76490febeb68d99aa18a48265b08
2021/04/23 17:57:52 pushed blob: sha256:72164b581b02b1eb297b403bcc8fc1bfa245cb52e103a3a525a0835a58ff58e2
2021/04/23 17:57:56 pushed blob: sha256:5dea5ec2316d4a067b946b15c3c4f140b4f2ad607e73e9bc41b673ee5ebb99a3
2021/04/23 17:58:07 pushed blob: sha256:d99fea081f251cc06ce68ce7cb224e2a0f63babd03ee9dd6bb03f6bf76dcb5a5
2021/04/23 17:58:08 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest: digest: sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0 size: 750
2021/04/23 17:58:08 Published zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0
zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0

也支持相对路径编译，如下

cd $GOPATH/src/github.com/http-helloworld/cmd/helloworld
ko publish ./

5. Ko resolve

创建文件deploy.yaml ，yaml 内容如下

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
spec:
  selector:
    matchLabels:
      foo: bar
  replicas: 1
  template:
    metadata:
      labels:
        foo: bar
    spec:
      containers:
      - name: hello-world
        # This is the import path for the Go binary to build and run.
        image: ko://github.com/http-helloworld/cmd/helloworld
        ports:
        - containerPort: 8080

然后执行 ko resolve -f deploy.yaml 结果如下，可以看到 ko://github.com/http-helloworld/cmd/helloworld 被替换成了 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0

$ ko resolve -f deploy.yaml

2021/04/23 22:09:19 Using base gcr.io/distroless/static:nonroot for github.com/http-helloworld/cmd/helloworld
2021/04/23 22:09:19 No matching credentials were found for "gcr.io/distroless/static", falling back on anonymous
2021/04/23 22:09:23 Building github.com/http-helloworld/cmd/helloworld for linux/amd64
2021/04/23 22:09:24 Publishing zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest
2021/04/23 22:09:31 existing blob: sha256:5dea5ec2316d4a067b946b15c3c4f140b4f2ad607e73e9bc41b673ee5ebb99a3
2021/04/23 22:09:31 existing blob: sha256:d99fea081f251cc06ce68ce7cb224e2a0f63babd03ee9dd6bb03f6bf76dcb5a5
2021/04/23 22:09:32 existing blob: sha256:72164b581b02b1eb297b403bcc8fc1bfa245cb52e103a3a525a0835a58ff58e2
2021/04/23 22:09:32 existing blob: sha256:a3e2b18c53ecc2aab65b3b70e5c16486e48f76490febeb68d99aa18a48265b08
2021/04/23 22:09:32 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest: digest: sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0 size: 750
2021/04/23 22:09:32 Published zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world
spec:
  selector:
    matchLabels:
      foo: bar
  replicas: 1
  template:
    metadata:
      labels:
        foo: bar
    spec:
      containers:
        - name: hello-world
          # This is the import path for the Go binary to build and run.
          image: zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0
          ports:
            - containerPort: 8080

6. Ko apply

ko apply -f xxx.yaml 用法同 kubectl apply -f xxx.yaml ,不同的是，ko apply -f 相当于先执行 resolve 将 ko://xxx 替换成镜像地址，然后再执行 kubectl apply -f 。

$ cd $GOPATH/src/github.com/http-helloworld/config
$ ko apply -f ./

2021/04/23 22:18:10 Using base gcr.io/distroless/static:nonroot for github.com/http-helloworld/cmd/helloworld
2021/04/23 22:18:10 No matching credentials were found for "gcr.io/distroless/static", falling back on anonymous
2021/04/23 22:18:13 Building github.com/http-helloworld/cmd/helloworld for linux/amd64
2021/04/23 22:18:15 Publishing zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest
2021/04/23 22:18:24 existing blob: sha256:a3e2b18c53ecc2aab65b3b70e5c16486e48f76490febeb68d99aa18a48265b08
2021/04/23 22:18:24 existing blob: sha256:d99fea081f251cc06ce68ce7cb224e2a0f63babd03ee9dd6bb03f6bf76dcb5a5
2021/04/23 22:18:24 existing blob: sha256:72164b581b02b1eb297b403bcc8fc1bfa245cb52e103a3a525a0835a58ff58e2
2021/04/23 22:18:24 existing blob: sha256:5dea5ec2316d4a067b946b15c3c4f140b4f2ad607e73e9bc41b673ee5ebb99a3
2021/04/23 22:18:25 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest: digest: sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0 size: 750
2021/04/23 22:18:25 Published zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:21d352ec9f9079f8da4c91cfe2461df51a404c079f262390b19fff4cb2ce15a0
deployment.apps/hello-world configured

7. 替换基础镜像

可以通过 ko 的 config 文件中的 defaultBaseImage 变量来设置基础镜像, 配置文件名为 .ko.yaml ,

ko 执行时默认会在当前目录下寻找 .ko.yaml 文件，也可以通过 环境变量 KO_CONFIG_PATH 来指定 .ko.yaml 的路径

# ~/.ko.yaml
defaultBaseImage: ubuntu

执行如下

$ export KO_CONFIG_PATH=~/
$ ko apply  -f ./config

2021/04/23 22:28:50 Using base ubuntu for github.com/http-helloworld/cmd/helloworld
2021/04/23 22:29:00 Building github.com/http-helloworld/cmd/helloworld for linux/amd64
2021/04/23 22:29:01 Publishing zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest
2021/04/23 22:29:14 existing blob: sha256:72164b581b02b1eb297b403bcc8fc1bfa245cb52e103a3a525a0835a58ff58e2
2021/04/23 22:29:14 existing blob: sha256:d99fea081f251cc06ce68ce7cb224e2a0f63babd03ee9dd6bb03f6bf76dcb5a5
2021/04/23 22:29:14 mounted blob: sha256:a70d879fa5984474288d52009479054b8bb2993de2a1859f43b5480600cecb24
2021/04/23 22:29:14 mounted blob: sha256:c4394a92d1f8760cf7d17fee0bcee732c94c5b858dd8d19c7ff02beecf3b4e83
2021/04/23 22:29:14 mounted blob: sha256:10e6159c56c084c858f5de2416454ac0a49ddda47b764e4379c5d5a147c9bf5f
2021/04/23 22:29:16 pushed blob: sha256:91d93e3477d55b71f5760478dcab690846ca5f76d92bbef874970460b3e73e5b
2021/04/23 22:29:17 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest: digest: sha256:623cb60ff10751f3f6a5f6570aaf5f49aee5fb6afc1ef5cfde4dd48a8b4d57df size: 1072
2021/04/23 22:29:17 Published zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:623cb60ff10751f3f6a5f6570aaf5f49aee5fb6afc1ef5cfde4dd48a8b4d57df
deployment.apps/hello-world configured

还可以 通过.ko.yaml 文件中的 baseImageOverrides 对指定编译二进制替换基础镜像，如本示例中，设置如下：

# ~/.ko.yaml
defaultBaseImage: ubuntu
baseImageOverrides: 
  github.com/http-helloworld/cmd/helloworld: centos

修改 .ko.yaml 后，执行命令

$ ko apply -f config

2021/04/23 22:38:14 Using base centos for github.com/http-helloworld/cmd/helloworld
2021/04/23 22:38:26 Building github.com/http-helloworld/cmd/helloworld for linux/amd64
2021/04/23 22:38:27 Publishing zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest
2021/04/23 22:38:29 existing blob: sha256:72164b581b02b1eb297b403bcc8fc1bfa245cb52e103a3a525a0835a58ff58e2
2021/04/23 22:38:29 existing blob: sha256:d99fea081f251cc06ce68ce7cb224e2a0f63babd03ee9dd6bb03f6bf76dcb5a5
2021/04/23 22:38:29 mounted blob: sha256:7a0437f04f83f084b7ed68ad9c4a4947e12fc4e1b006b38129bac89114ec3621
2021/04/23 22:38:32 pushed blob: sha256:e909db5555a2c7310e605e60a47a98661c9a5c54d567f741a8d677f84c8a887f
2021/04/23 22:38:32 zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648:latest: digest: sha256:dc009335be23a9eee0235e425218f18a68c3210b00adac7cfe736d9bf38f4121 size: 752
2021/04/23 22:38:32 Published zhaojizhuang66/helloworld-cbcbba9849adcc25ce56a08dfd597648@sha256:dc009335be23a9eee0235e425218f18a68c3210b00adac7cfe736d9bf38f4121
deployment.apps/hello-world configured