Dunia D2: Resepi

WORKDIR, RUN, ENV dan EXPOSE

Anda akan belajar: empat lagi baris resepi, dan kenapa EXPOSE tak buka tingkap.

Teks BM belum disemak oleh penutur asli.

Disemak dengan Docker Engine 29 pada 31 Okt 2026

Masalahnya

Satu resepi tulis COPY server.js . sahaja. Asas node tak tetapkan folder kerja. Di mana server.js mendarat?

Tengok

~/api $ cat DockerfileFROM node:24-alpineWORKDIR /appCOPY package.json package-lock.json ./RUN npm ci --omit=devCOPY server.js .ENV PORT=3000EXPOSE 3000CMD ["node", "server.js"]~/api $ docker build -t api:1.0 .[+] Building 1.3s (10/10) FINISHED                                docker:default => [internal] load build definition from Dockerfile                        0.0s => => transferring dockerfile: 200B                                        0.0s => [internal] load metadata for docker.io/library/node:24-alpine           0.0s => [internal] load .dockerignore                                           0.0s => => transferring context: 2B                                             0.0s => [1/5] FROM docker.io/library/node:24-alpine@sha256:8a32c8cf649a49915a6  0.0s => => resolve docker.io/library/node:24-alpine@sha256:8a32c8cf649a49915a6  0.0s => [2/5] WORKDIR /app                                                      0.0s => [internal] load build context                                           0.0s => => transferring context: 675B                                           0.0s => [3/5] COPY package.json package-lock.json ./                            0.0s => [4/5] RUN npm ci --omit=dev                                             1.2s => [5/5] COPY server.js .                                                  0.0s => exporting to image                                                      0.1s => => exporting layers                                                     0.0s => => exporting manifest sha256:585b1f71ac0676785e33f0a3e3cc27827b1895c98  0.0s => => exporting config sha256:750e26492fb9c3a3ec58b7ad77189f271fe577845a2  0.0s => => exporting attestation manifest sha256:27da90d7c6fda90a44952daaae018  0.0s => => exporting manifest list sha256:8979cf17b5a929255f570efe837792395db7  0.0s => => naming to docker.io/library/api:1.0                                  0.0s => => unpacking to docker.io/library/api:1.0                               0.0s~/api $ docker run --rm api:1.0 pwd/app

Laptop anda`~/api`

Tiada tingkap terbuka

Bekas (container)

Belum ada container

Pek beku (image)

node:24-alpine4 layer · 244MB

WORKDIR /app ialah kaunter kerja anda. Semua baris selepasnya bekerja di situ. RUN memasak semasa membakar: di sini ia pasang pakej. pwd cetak kaunter itu: /app.

Cuba

Sesetengah baris bakar satu layer (lapisan). Yang lain cuma tampal nota pada pek. Asingkan mereka.

Seret kad ke dalam kotak. Atau ketik kad, kemudian ketik kotak.

Cuba

Image sudah dibina. Jalankan dengan tingkap 3000 terbuka, kemudian ketuk dengan curl.

Laptop anda`~/api`

Tiada tingkap terbuka

Bekas (container)

Belum ada container

Pek beku (image)

api:1.08 layer · 244MB
node:24-alpine4 layer · 244MB

Petunjuk

-p 3000:3000 buka tingkap: port laptop, kemudian port container.

Teka

Resepi tulis EXPOSE 3000. Anda jalankan image tanpa -p. Boleh laptop anda capai port 3000?

Semak

~/api $ docker build -t api:1.0 .[+] Building 1.3s (10/10) FINISHED                                docker:default => [internal] load build definition from Dockerfile                        0.0s => => transferring dockerfile: 200B                                        0.0s => [internal] load metadata for docker.io/library/node:24-alpine           0.0s => [internal] load .dockerignore                                           0.0s => => transferring context: 2B                                             0.0s => [1/5] FROM docker.io/library/node:24-alpine@sha256:8a32c8cf649a49915a6  0.0s => => resolve docker.io/library/node:24-alpine@sha256:8a32c8cf649a49915a6  0.0s => [2/5] WORKDIR /app                                                      0.0s => [internal] load build context                                           0.0s => => transferring context: 675B                                           0.0s => [3/5] COPY package.json package-lock.json ./                            0.0s => [4/5] RUN npm ci --omit=dev                                             1.2s => [5/5] COPY server.js .                                                  0.0s => exporting to image                                                      0.1s => => exporting layers                                                     0.0s => => exporting manifest sha256:dc7800314dac8d66f0fd744a66287432eab0b43b6  0.0s => => exporting config sha256:00e8092d135c2dc5c2f015b20bb84dce74869227e7d  0.0s => => exporting attestation manifest sha256:9c156a337bb43693fe0cc0122bbdc  0.0s => => exporting manifest list sha256:6e4d6a6a470157a9a2bcaa8ec14418cc8756  0.0s => => naming to docker.io/library/api:1.0                                  0.0s => => unpacking to docker.io/library/api:1.0                               0.0s~/api $ docker run -d --name api api:1.09ae7e68b27cc6db02c55bc670db9280e69420649f964a99d83abb26f458d10b0~/api $ curl localhost:3000curl: (7) Failed to connect to localhost port 3000 after 0 ms: Couldn't connect to server~/api $ docker psCONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS         PORTS      NAMES9ae7e68b27cc   api:1.0   "docker-entrypoint.s…"   6 seconds ago   Up 6 seconds   3000/tcp   api

Laptop anda`~/api`

Tiada tingkap terbuka

Bekas (container)

Belum ada container

Pek beku (image)

node:24-alpine4 layer · 244MB

Ralat sebenar: Couldn't connect to server. Maksudnya: tiada tingkap terbuka. docker ps tunjuk 3000/tcp tanpa anak panah.

Cuba

ENV PORT=3000 cuma nilai asal. Bina arahan yang jalankan API di port 4000.

Ketik kepingan ikut turutan yang betul.

…

Anda berjaya!

Kini anda boleh guna WORKDIR, RUN, ENV dan EXPOSE.

Nak tahu lebih (pilihan)

Gabungkan arahan berkaitan dalam satu RUN dengan &&. Satu RUN, satu layer. EXPOSE juga bantu docker run -P, yang buka setiap port yang di-expose pada port laptop rawak.

Misi sebenar

Tambah WORKDIR /app pada resepi anda dari pelajaran 1.
Bina semula.
docker build -t hello:1.1 .
Semak folder kerja.
docker run --rm hello:1.1 pwd

0 daripada 3 langkah siap · Tanda anda disimpan.

WORKDIR, RUN, ENV dan EXPOSE

Laptop anda~/api

Bekas (container)

Pek beku (image)

Laptop anda~/api

Bekas (container)

Pek beku (image)

Laptop anda~/api

Bekas (container)

Pek beku (image)

Laptop anda`~/api`

Laptop anda`~/api`

Laptop anda`~/api`