Use alpine docker file

[justgage]

I'm no docker expert by any means but it seems this works locally, this should reduce the download size by a great amount.

[westy92]

RUN apk add --no-cache git libcap shadow
Removes the need to run apk update and to remove package lists after.

[justgage]

Nice! Didn't know that.

[westy92]

Why not group all of these RUNs into one layer like the existing image?

[justgage]

Splitting it up (from my limited knowlege) allows if you change the lower ones the upper ones will be cached, meaning you won't have to run the higher ones nearly as often. Perhaps I missunderstood that though.

[justgage]

In my most recent PR I've organized it so that it should cache installing the depenecies (changes infrequently). I found what helped the most was moving the COPY down. However It seems from this discussion that there's tradofs of caching for file size differences: https://stackoverflow.com/questions/39223249/multiple-run-vs-single-chained-run-in-dockerfile-what-is-better

[justgage]

I deleted these comments because I don't think they were bringing much value, however I can put them back due to that being outside the scope of this PR

[dsperling]

@justgage there is a great Dockerfile best practices article here. I thought I would pass it along.
https://docs.docker.com/develop/develop-images/dockerfile_best-practices/

Following these recommendations, specifically for RUN, it will create a more readable Dockerfile:

FROM golang:1.9-alpine

RUN apk add --no-cache \
    git \
    libcap \
    shadow \
 && addgroup -g 1000 -S freegeoip \
 && adduser -u 1000 -S freegeoip -G freegeoip

COPY cmd/freegeoip/public /var/www
COPY . /go/src/github.com/apilayer/freegeoip

WORKDIR /go/src/github.com/apilayer/freegeoip/cmd/freegeoip

RUN go get -d \
 && go install \
 && setcap cap_net_bind_service=+ep /go/bin/freegeoip

ENTRYPOINT ["/go/bin/freegeoip"]
USER freegeoip

EXPOSE 8080

Notice that the ADD was changed to a COPY as per the recommendation here on transparency.

[justgage]

I'm sure you're busy but when you have time I think this is ready for another code review @westy92

[justgage]

@westy92 thanks for approving it. I don't have write access to hit merge but perhaps you're waiting to do that anyway, not sure.

[westy92]

I have no authority here, merely a user trying to provide valuable input.

[OlagStegan]

A rebuild produced this error

Step 10/13 : RUN useradd -ms /bin/bash freegeoip
 ---> Running in afcee3ec8484
Creating mailbox file: No such file or directory

but otherwise image rebuilt and installed OK fully functioning on :80
still outstanding issue on :443 #3

[justgage]

Yeah, I looked up that error hoping I could fix it, however after my reserach it seemed like there wasn't a great way to fix it, and it doesn't cause issues. I could create the directory that it's trying to access but I was afraid that would only add to the image size (not sure of that though)?

[dsperling]

According to this ticket, mhart/alpine-node#48, the correct way to add a user in Apline 3.7 is:

RUN \
      addgroup -g 1000 -S freegeoip && \
      adduser -u 1000 -S freegeoip -G freegeoip

The base image golang:1.9-alpine is currently running 3.6.2, but this still seems to correctly create the home directory:

echo $HOME
/home/freegeoip

[justgage]

followed @dsperling advice, seems the errors are gone @OlagStegan