Multistage build na prática
Last updated
Last updated
Aplicação web escrita em Go.
go.mod:
module barbieri.dev/webteste
go 1.18main.go:
package main
import (
"fmt"
"net/http"
)
func hello(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "<h1>Página de teste</h1>")
}
func main() {
http.HandleFunc("/", hello)
fmt.Println("Servidor rodando na porta 8080")
http.ListenAndServe(":8080", nil)
}
$ pwd
/tmp/go
$ ls
go.mod main.go$ sudo apt update
$ sudo apt install golang
$ go run main.go
Servidor rodando na porta 8080Criação da imagem de container:
$ touch Dockerfile.simples
$ code .$ go version
go version go1.18.1 linux/amd64O GO é uma linguagem compilada. Faz-se necessário compilar a aplicação para obter o binário.
FROM golang:1.18.1
WORKDIR /app
COPY . .
# compilacao da aplicacao
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main .
CMD ["./main"]Construção da imagem:
$ pwd
/tmp/go
$ ls
Dockerfile.simples go.mod main.go
$ docker build -t marcelodpbarbieri/app-multi-stage:simples -f Dockerfile.simples .
[+] Building 9.0s (9/9) FINISHED docker:default
=> [internal] load build definition from Dockerfile.simples 0.0s
=> => transferring dockerfile: 200B 0.0s
=> [internal] load metadata for docker.io/library/golang:1.18.1 1.1s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [1/4] FROM docker.io/library/golang:1.18.1@sha256:12d3995156cb0dc 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 92B 0.0s
=> CACHED [2/4] WORKDIR /app 0.0s
=> [3/4] COPY . . 0.0s
=> [4/4] RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo 7.6s
=> exporting to image 0.3s
=> => exporting layers 0.2s
=> => writing image sha256:8e8245117427e08df5b2125f8d45c3f0dee8b70cd 0.0s
=> => naming to docker.io/marcelodpbarbieri/app-multi-stage:simples 0.0s
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
marcelodpbarbieri/app-multi-stage simples 8e8245117427 32 seconds ago 1.02GBExecução do container:
$ docker container run -d -p 8080:8080 marcelodpbarbieri/app-multi-stage:simples
1f5867bf8e016dc8b8aa85e38a17856ddec35a8028b5aaf76e5a57b578858a4f
$ docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1f5867bf8e01 marcelodpbarbieri/app-multi-stage:simples "./main" 41 seconds ago Up 40 seconds 0.0.0.0:8080->8080/tcp, :::8080->8080/tcp nifty_merkleFuncionou, porém a imagem construída possui aproximadamente 1GB de tamanho. Todo o SDK do GoLang está sendo carregado.
Para verificar o tamanho da imagem do GoLang, pode ser feito pelo history da imagem ou com o pull:
$ docker image history marcelodpbarbieri/app-multi-stage:simples
IMAGE CREATED CREATED BY SIZE COMMENT
8e8245117427 4 minutes ago CMD ["./main"] 0B buildkit.dockerfile.v0
<missing> 4 minutes ago RUN /bin/sh -c CGO_ENABLED=0 GOOS=linux go b… 60.1MB buildkit.dockerfile.v0
<missing> 4 minutes ago COPY . . # buildkit 463B buildkit.dockerfile.v0
<missing> 7 minutes ago WORKDIR /app 0B buildkit.dockerfile.v0
<missing> 2 years ago /bin/sh -c #(nop) WORKDIR /go 0B
<missing> 2 years ago /bin/sh -c mkdir -p "$GOPATH/src" "$GOPATH/b… 0B
<missing> 2 years ago /bin/sh -c #(nop) ENV PATH=/go/bin:/usr/loc… 0B
<missing> 2 years ago /bin/sh -c #(nop) ENV GOPATH=/go 0B
<missing> 2 years ago /bin/sh -c set -eux; arch="$(dpkg --print-a… 431MB
<missing> 2 years ago /bin/sh -c #(nop) ENV GOLANG_VERSION=1.18.1 0B
<missing> 2 years ago /bin/sh -c #(nop) ENV PATH=/usr/local/go/bi… 0B
<missing> 2 years ago /bin/sh -c set -eux; apt-get update; apt-g… 228MB
<missing> 2 years ago /bin/sh -c apt-get update && apt-get install… 152MB
<missing> 2 years ago /bin/sh -c set -ex; if ! command -v gpg > /… 19MB
<missing> 2 years ago /bin/sh -c set -eux; apt-get update; apt-g… 10.7MB$ docker pull golang:1.18.1
1.18.1: Pulling from library/golang
6aefca2dc61d: Already exists
967757d56527: Already exists
c357e2c68cb3: Already exists
c766e27afb21: Already exists
d6a8ea6bd5f8: Already exists
13a9b904f742: Already exists
3447e3508f49: Already exists
Digest: sha256:12d3995156cb0dcdbb9d3edb5827e4e8e1bf5bf92436bfd12d696ec997001a9a
Status: Downloaded newer image for golang:1.18.1
docker.io/library/golang:1.18.1
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
golang 1.18.1 65375c930b21 2 years ago 964MB$ touch Dockerfile.multistage
$ code .Verificação do tamanho das imagens Alpine e Ubuntu:
$ docker image pull alpine:3.20.2
3.20.2: Pulling from library/alpine
c6a83fedfae6: Already exists
Digest: sha256:0a4eaa0eecf5f8c050e5bba433f58c052be7587ee8af3e8b3910ef9ab5fbe9f5
Status: Downloaded newer image for alpine:3.20.2
docker.io/library/alpine:3.20.2
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
alpine 3.20.2 324bc02ae123 4 weeks ago 7.8MB$ docker image pull ubuntu
Using default tag: latest
latest: Pulling from library/ubuntu
31e907dcc94a: Already exists
Digest: sha256:8a37d68f4f73ebf3d4efafbcf66379bf3728902a8038616808f04e34a9ab63ee
Status: Downloaded newer image for ubuntu:latest
docker.io/library/ubuntu:latest
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest edbfe74c41f8 3 weeks ago 78.1MBDockerfile.multistage:
# IMAGEM INTERMEDIARIA
# imagem base nomeada como build
FROM golang:1.18.1 AS build
WORKDIR /build
COPY . .
# compilacao da aplicacao
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main .
# IMAGEM FINAL
# imagem base nomeada como app
FROM alpine:3.20.2 AS app
WORKDIR /app
# copia do binario da imagem intermediaria (build) para a imagem final
COPY --from=build /build/main .
CMD ["./main"]Construção da imagem:
$ docker image build -t marcelodpbarbieri/app-multi-stage:multistage -f Dockerfile.multistage . -
[+] Building 7.6s (13/13) FINISHED docker:default
=> [internal] load build definition from Dockerfile.multistage 0.0s
=> => transferring dockerfile: 387B 0.0s
=> [internal] load metadata for docker.io/library/alpine:3.20.2 0.0s
=> [internal] load metadata for docker.io/library/golang:1.18.1 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [build 1/4] FROM docker.io/library/golang:1.18.1 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 477B 0.0s
=> [app 1/3] FROM docker.io/library/alpine:3.20.2 0.0s
=> CACHED [app 2/3] WORKDIR /app 0.0s
=> CACHED [build 2/4] WORKDIR /build 0.0s
=> [build 3/4] COPY . . 0.0s
=> [build 4/4] RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main . 7.3s
=> [app 3/3] COPY --from=build /build/main . 0.1s
=> exporting to image 0.1s
=> => exporting layers 0.0s
=> => writing image sha256:067e8f0af08aa2f9ab71c1629ec0979bb0dcfb62c84ed7184440b6a90867c9bc 0.0s
=> => naming to docker.io/marcelodpbarbieri/app-multi-stage:multistage 0.0s
$ docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
marcelodpbarbieri/app-multi-stage multistage 067e8f0af08a 9 seconds ago 14MB
marcelodpbarbieri/app-multi-stage simples 8e8245117427 21 minutes ago 1.02GBA imagem agora possui tamanho de 14MB
$ docker history 067e
IMAGE CREATED CREATED BY SIZE COMMENT
067e8f0af08a 9 minutes ago CMD ["./main"] 0B buildkit.dockerfile.v0
<missing> 9 minutes ago COPY /build/main . # buildkit 6.24MB buildkit.dockerfile.v0
<missing> 10 minutes ago WORKDIR /app 0B buildkit.dockerfile.v0
<missing> 4 weeks ago /bin/sh -c #(nop) CMD ["/bin/sh"] 0B
<missing> 4 weeks ago /bin/sh -c #(nop) ADD file:99093095d62d04215… 7.8MBExecução do container:
$ docker container run -d -p 8080:8080 marcelodpbarbieri/app-multi-stage:multistage
fd52b4647f011f8dca6be2fbc9f9b752caf0babe735acf122d9de2b44fbf61f7
