Podman build Multi-Arch Images

1. 撰寫 go 範例程式

   nano hello.go

   檔案內容如下：

   package main
   
   import (
           "fmt"
           "net/http"
   )
   
   func handler(w http.ResponseWriter, r *http.Request) {
           fmt.Fprintf(w, "Hello")
   }
   
   func main() {
           http.HandleFunc("/", handler)
           http.ListenAndServe(":8080", nil)
   }

2. 編輯 Dockerfile

   nano Dockerfile

   檔案內容如下：

   FROM --platform=$BUILDPLATFORM docker.io/library/golang:1.22 AS builder
   
   ARG TARGETOS
   ARG TARGETARCH
   
   WORKDIR /app
   COPY . .
   
   # 利用 Go 的環境變數進行交叉編譯
   RUN GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o /build/hello hello.go
   
   # 最後階段
   FROM scratch
   COPY --from=builder /build/hello /usr/local/bin/hello
   CMD ["/usr/local/bin/hello"]

3. 初始化 image manifest

   podman manifest create hello

   執行結果：

   413534f46ca55438f717d734a4e088af1a92b003c6c837cf5753b6808161b125

4. build image

   podman build --platform linux/amd64,linux/arm64 --manifest localhost/hello .

   執行結果：

   [linux/arm64] [1/2] STEP 1/6: FROM docker.io/library/golang:1.22 AS builder
   [linux/arm64] [1/2] STEP 2/6: ARG TARGETOS
   --> 6af98f118a47
   [linux/arm64] [1/2] STEP 3/6: ARG TARGETARCH
   --> de656f2a8f6b
   [linux/arm64] [1/2] STEP 4/6: WORKDIR /app
   --> 2e367870d334
   [linux/arm64] [1/2] STEP 5/6: COPY . .
   --> 6ad772c2ca91
   [linux/arm64] [1/2] STEP 6/6: RUN GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o /build/hello hello.go
   --> 30515c7aaf86
   [linux/arm64] [2/2] STEP 1/3: FROM scratch
   [linux/arm64] [2/2] STEP 2/3: COPY --from=builder /build/hello /usr/local/bin/hello
   --> 4ac0f5942408
   [linux/arm64] [2/2] STEP 3/3: CMD ["/usr/local/bin/hello"]
   [linux/arm64] [2/2] COMMIT
   --> 6251d8b5a1f3
   [linux/amd64] [1/2] STEP 1/6: FROM docker.io/library/golang:1.22 AS builder
   6251d8b5a1f392aed47bc124a0bd3f2b7c18f3d4ba9681ea153e853bf5d23370
   [linux/amd64] [1/2] STEP 2/6: ARG TARGETOS
   --> Using cache 6af98f118a47e4fbbcaff838816b73e31d7f5bd72e4b546baf82b026fe424662
   --> 6af98f118a47
   [linux/amd64] [1/2] STEP 3/6: ARG TARGETARCH
   --> Using cache de656f2a8f6bc7fc0e3f97eaaff21df053837e3d0e1a97f659a8a0ca40e2bb4a
   --> de656f2a8f6b
   [linux/amd64] [1/2] STEP 4/6: WORKDIR /app
   --> Using cache 2e367870d3341f7f57dbf1a1924281e277a645ecb29f031a979ea6f656ef2c07
   --> 2e367870d334
   [linux/amd64] [1/2] STEP 5/6: COPY . .
   --> Using cache 6ad772c2ca9135caef7c1fbeb79c126b36638dccab3b8eac884642020f330b4a
   --> 6ad772c2ca91
   [linux/amd64] [1/2] STEP 6/6: RUN GOOS=$TARGETOS GOARCH=$TARGETARCH go build -o /build/hello hello.go
   --> afbe26b87b3c
   [linux/amd64] [2/2] STEP 1/3: FROM scratch
   [linux/amd64] [2/2] STEP 2/3: COPY --from=builder /build/hello /usr/local/bin/hello
   --> 6dcdcf58bf83
   [linux/amd64] [2/2] STEP 3/3: CMD ["/usr/local/bin/hello"]
   [linux/amd64] [2/2] COMMIT
   --> b6c0da75b480
   b6c0da75b480acb9283ba0978937fe3668490c17bd39739a02211b1079227752

5. 檢視 image

   podman images localhost/hello:latest

   執行結果：

   REPOSITORY       TAG         IMAGE ID      CREATED         SIZE
   <none>           <none>      b6c0da75b480  20 minutes ago  7.07 MB
   localhost/hello  latest      413534f46ca5  25 minutes ago  1.04 kB

6. 檢視 image manifest

   podman manifest inspect localhost/hello:latest

   執行結果：

   {
       "schemaVersion": 2,
       "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
       "manifests": [
           {
               "mediaType": "application/vnd.oci.image.manifest.v1+json",
               "size": 498,
               "digest": "sha256:48c8c68bc197b35831750d260600d3eb6c127ac64463d8f26d4f369e801ec4dd",
               "platform": {
                   "architecture": "arm64",
                   "os": "linux"
               }
           },
           {
               "mediaType": "application/vnd.oci.image.manifest.v1+json",
               "size": 498,
               "digest": "sha256:27a5911345bd07fc3461092bb0b7c5fb52fed1e35f4dd27eaf0cf833e2c19860",
               "platform": {
                   "architecture": "amd64",
                   "os": "linux"
               }
           }
       ]
   }

7. Push the manifest and included images

   podman manifest push localhost/hello:latest docker://quay.io/myuser/image:latest