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use docker multi stage build #2

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use docker multi stage build #2

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4ae39e4
use docker multi stage build
Anakin100100 Apr 28, 2022
7387374
make the workflow run on all pull requests
Anakin100100 Apr 28, 2022
a3344a3
make docker cache dependencies
Anakin100100 Apr 29, 2022
3c35fd3
run on push to main branch and on pull requests
Anakin100100 Apr 29, 2022
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13 changes: 5 additions & 8 deletions Dockerfile
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@@ -1,16 +1,13 @@
FROM golang:1.18
FROM golang:1.18 as builder

RUN mkdir /app
WORKDIR /app

COPY go.mod ./
COPY go.sum ./
RUN go mod download

COPY . .
RUN CGO_ENABLED=0 go build -o geralt

RUN go build -o /geralt

FROM alpine:3.15
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@galuszkak galuszkak Apr 29, 2022

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Alpine is a very risky choice and has proven to have an illusion of security, I think Debian makes more sense in this case.

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@galuszkak galuszkak Apr 29, 2022

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BTW default golang image is based on Debian and I think it's not an accidental choice.

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@Anakin100100 Anakin100100 Apr 29, 2022 •
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When introducing this change I was thinking more about the resulting image size than security. The final build using pure alpine (without go etc.) is only 16mb while the image resulting from go-1.18 was about 1.1gb in size. Though the debian image is fairly coveniat for running tests. Do you know whether GCP docker registry caches the layers of the base image? If this is the case, the cost effectivness of debian and alpine images would be the same except the base image size. Do you know if the image size affects the cold startup time? In this post the author says that it does not but I couldn't find another confirmation of that.

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@Anakin100100 Anakin100100 Apr 29, 2022 •
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I wasn't aware that alpine was unsafe and thought that it was best to use as minimal image as possible for security to decrease the number of attack vectors. Could you show me some examples? I'd like to read up on that.

COPY --from=builder /app/geralt /
EXPOSE 8080

CMD [ "/geralt" ]
CMD ["/geralt"]