Dockerize Golang App

Image by Todd Cravens

Assalamu’alaikum Warahmatullah Wabarakatuh,

Oke pada part3 ini kita akan coba bahas bagaimana caranya kita membuat docker images dari aplikasi golang kita sebelum kita deploy ke kubernetes cluser.

Sebelum kita mulai, pastikan terlelbih dahulu kita telah menginstall docker engine di local komputer kita. Okeh kalo udah diinstall langsung aja kita masuk ke tahap pembuatan Dockerfile.

Jadi struktur folder projectnya :

Dan ini Dockerfile yang aku bikin :

# Build Stage
# Images yang digunakan untuk build binary
FROM golang:alpine as build
# Environtment yang diperlukan menginstall package
ENV GO111MODULE=on
# Environtment yang diperlukan untuk nama user
ENV USER=appuser
# Environtment yang diperlukan untuk user id
ENV UID=10001
# Proses install package yang diperlukan
RUN apk update && apk add --no-cache git ca-certificates && update-ca-certificates
# Proses membuat user
RUN adduser \
--disabled-password \
--gecos "" \
--home "/nonexistent" \
--shell "/sbin/nologin" \
--no-create-home \
--uid "${UID}" \
"${USER}"
# Proses menentukan working directory
WORKDIR /app
# Copy file go.mod ke workdir
COPY ./go.mod .
# Proses installasi module yang dibutuhkan
RUN go mod download
# Proses mengcopy semua file & folder yang akan dibuild
COPY . .
# Environtment yang dibutuhkan dalam proses build binary app
ENV CGO_ENABLED=0 GOOS=linux GOARCH=amd64
# Proses build binary golang app
RUN go build -a -installsuffix cgo -ldflags="-s -w" -o main .
# Wraping Stages
# Images yang digunakan untuk wrap binary
FROM busybox
# Proses menentukan working directory
WORKDIR /app
# Meng-copy ca-certificates
COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
# Meng-copy passwd file
COPY --from=build /etc/passwd /etc/passwd
# Meng-copy group file
COPY --from=build /etc/group /etc/group
# Meng-copy binary app golang
COPY --from=build /app/main /app/main
# Menganti user ke user appuser
USER appuser:appuser
# Proses expose port
EXPOSE 3000
# Perintah yang akan pertama kali dijalankan pada saat container berjalan
CMD [ "/app/main" ]

Dan ini isi file dari .dockerignore :

.github/*
.kubernetes/*
.gitignore
output.json
README.md
main_test.go

Okeh selanjutnya kita lanjut ke proses build Dockerfile ini menjadi docker images. Langsung aja kita jalanin perintah :

docker build . -t simple-http-app:latest

Output :

Sending build context to Docker daemon  510.5kB
Step 1/21 : FROM golang:alpine as build
---> d8bf44a3f6b4
Step 2/21 : ENV GO111MODULE=on
---> Using cache
---> 9e17d05c95e8
Step 3/21 : ENV USER=appuser
---> Using cache
---> 454333f81981
Step 4/21 : ENV UID=10001
---> Using cache
---> 47524e3dd343
Step 5/21 : RUN apk update && apk add --no-cache git ca-certificates && update-ca-certificates
---> Using cache
---> 4ad0e65a22a5
Step 6/21 : RUN adduser     --disabled-password     --gecos ""     --home "/nonexistent"     --shell "/sbin/nologin"     --no-create-home     --uid "${UID}"     "${USE
R}"
---> Using cache
---> d314ff24944e
Step 7/21 : WORKDIR /app
---> Using cache
---> b0be7d4dc8af
Step 8/21 : COPY ./go.mod .
---> Using cache
---> 3a47a13d3cd1
Step 9/21 : RUN go mod download
---> Using cache
---> e5972ad4feb5
Step 10/21 : COPY . .
---> 3dca5a2ac611
Step 11/21 : ENV CGO_ENABLED=0 GOOS=linux GOARCH=amd64
---> Running in b047f6f855cc
Removing intermediate container b047f6f855cc
---> 8ad66335466c
Step 12/21 : RUN go build -a -installsuffix cgo -ldflags="-s -w" -o main .
---> Running in 9368f2b33819
Removing intermediate container 9368f2b33819
---> 10472b6cddff
Step 13/21 : FROM busybox
---> beae173ccac6
Step 14/21 : WORKDIR /app
---> Using cache
---> 2abe9564862d
Step 15/21 : COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
---> Using cache
---> 720ca1a731f7
Step 16/21 : COPY --from=build /etc/passwd /etc/passwd
---> Using cache
---> 14a4d7786490
Step 17/21 : COPY --from=build /etc/group /etc/group
---> Using cache
---> d9073e7ff574
Step 18/21 : COPY --from=build /app/main /app/main
---> 1d17d57e962b
Step 19/21 : USER appuser:appuser
---> Running in 9bb09512be0d
Removing intermediate container 9bb09512be0d
---> 3042e12c73f7
Step 20/21 : EXPOSE 3000
---> Running in de072f21fe05
Removing intermediate container de072f21fe05
---> cb8f322947e8
Step 21/21 : CMD [ "/app/main" ]
---> Running in 06fe93a49835
Removing intermediate container 06fe93a49835
---> 672395de6388
Successfully built 672395de6388
Successfully tagged simple-http-app:latest

Untuk mengetahui ukuran docker images tadi, kita bisa jalankan perintah docker images

Output :

REPOSITORY                    TAG                 IMAGE ID       CREATED              SIZE
simple-http-app               latest              672395de6388   About a minute ago   7.07MB

Wokeh, sudah selesai.

Selanjutnya kita lanjut ke part4, untuk membuat testing dari aplikasi golang kita.

See you~

About me

I’m Muhammad Abdur Rofi Maulidin, a DevOps Engineer passionate about optimizing software development processes by supporting cloud infrastructure management like kubernetes orchestration, and automations. Dedicated to support the reliability, availability, and performance of systems by implementing SLI/SLO based on performance monitoring for business requirement.

Feel free to keep in touch with me:

• LinkedIn: https://www.linkedin.com/in/mrofisr/
• Twitter: https://twitter.com/mrofisr_
• Telegram: https://t.me/@mrofisr

Let’s go to the cloud 🚀

Free Palestine 🇵🇸