標籤: CI / CD

進行多階段構建時，builder image通常很佔空間，
尤其當系統架構是微服務，又做了自動化建構時，可能三兩天Runner硬碟就會滿載，
透過image filter的設定，可以用來刪除編譯時產生的builder image，
例如：

FROM builder-image:latest as builder
LABEL stage=builder
LABEL build=my-service
COPY . .
RUN go build -o app *.go
FROM alpine:latest
COPY --from=builder app .
CMD ["./app"]

build完之後，清理builder images

docker image prune -f --filter label=stage=builder --filter label=build=my-service

套用在Gitlab CI的話，可以利用CI_JOB_ID來實現，
先讓CI_JOB_ID，在編譯時帶入builder image：

FROM builder-image:latest as builder
ARG job_id
LABEL stage=builder
LABEL build=$job_id
COPY . .
RUN go build -o app *.go
FROM alpine:latest
COPY --from=builder app .
CMD ["./app"]

docker build --pull \
 --build-arg job_id=${CI_JOB_ID} \
 -t my-service:latest .

並在build job設定中新增after script：

.remove-intermediate-containers:
  after_script:
    - docker image prune -f --filter label=stage=builder --filter label=build=$CI_JOB_ID

參考資料：

https://docs.docker.com/engine/reference/commandline/images/#filtering

https://docs.gitlab.com/ee/ci/variables/#predefined-environment-variables