Liquidsoap in Docker Containers

[gAlleb]

#3925 (reply in thread)

Thank you, @vitoyucepi!

I don't know why you would use alpine:edge as a base image for a container, but I would prefer ubuntu instead.

I've just looked here: https://github.com/savonet/liquidsoap/blob/main/.github/docker/Dockerfile.production-alpine
And if I try to do the same with older versions I get

1.959 fetch https://dl-cdn.alpinelinux.org/alpine/v3.19/community/x86_64/APKINDEX.tar.gz
3.811 ERROR: unable to select packages:
3.822   so:libswresample.so.4 (no such package):
3.822     required by: liquidsoap-x86_64-2.2.5-r0[so:libswresample.so.4]

Main idea was keeping image minimal but with python3 and ffprobe.

Here are parts of my repo. All files are licensed under the GNU AGPLv3.

Looks nice, but some parts are not understandable. Why do you use both alpine and ubuntu? Alpine just to download the package?
I think I can build image with ubuntu but this would require super skills to know how to install only needed packages for LS .deb and cue_file to work. Because if one installs blindly - it would all take up to 1GB of space again.

entrypoint

This bit seems distant as ever.

[vitoyucepi]

Looks nice, but some parts are not understandable. Why do you use both alpine and ubuntu? Alpine just to download the package?

Yes, my containerfile uses alpine as the downloader. I used to use COPY to transfer files between stages, but that results in an additional non-removable layer.

it would all take up to 1GB of space again.

It won't, only 0.5 GB. Try to build it.
If you want a smaller image, you'll have to build liquidsoap and ffmpeg from source to disable all unused features.

[gAlleb]

Ha) Vito, It's Marvelous!

So I

FROM alpine:edge as downloader

ARG LIQUIDSOAP_VERSION=2.2.5

ARG LIQUIDSOAP_RELEASE="https://github.com/savonet/liquidsoap-release-assets/releases/download/v${LIQUIDSOAP_VERSION}"
ARG LIQUIDSOAP_APK="liquidsoap-x86_64-${LIQUIDSOAP_VERSION}-r0.apk"
ARG LIQUIDSOAP_SHA512SUM="0d433e902b296cc53f26d52c3805c1880b3a916898b4ac709120017803e787c57530974fab4e4b33df0237f70f0f40ecb1ad91e9bcedfad0cccafe8a37edcedc"

RUN set -eux; \
      mkdir /packages; \
      wget "${LIQUIDSOAP_RELEASE}/${LIQUIDSOAP_APK}" -O /packages/liquidsoap.apk; \
      echo "${LIQUIDSOAP_SHA512SUM}  /packages/liquidsoap.apk" | sha512sum -c -;

FROM alpine:edge
ENV TZ=UTC
RUN --mount=type=bind,target=/packages,source=/packages,from=downloader \
    apk add --no-cache --allow-untrusted \
      -X https://dl-cdn.alpinelinux.org/alpine/edge/testing \
      /packages/liquidsoap.apk \
      ffmpeg \
      python3 \
      tzdata \
    ;

USER liquidsoap

COPY rootfs /

ENTRYPOINT [ "entrypoint" ]

And it works with my docker compose! Ha!

So entrypoint turns out to be an important thing!

Thanks!
Tell me more! I'm kidding) But do.

[vitoyucepi]

Just one more thing.

1. If you use my entrypoint, you don't need to define USER liquidsoap, but you do need to add su-exec. Here is the entrypoint script for alpine. The license is GNU AGPLv3.

   #!/usr/bin/env sh
   
   set -eu
   
   main() {
     if [ "${1#-}" != "$1" ] || [ "${1%.liq}" != "$1" ]; then
       set -- liquidsoap "$@"
     fi
   
     if [ "$1" = 'liquidsoap' ] && [ "$(id -u)" -eq '0' ]; then
       exec su-exec liquidsoap "$0" "$@"
     fi
   
     exec "$@"
   }
   
   main "$@"

2. To test things, you don't even need any of these commands, just set ENTRYPOINT [ "liquidsoap" ] and use CMD or command to select the script.

3. If you do http requests, then you should also install ca-certificates.

[gAlleb]

I see.

If you do http requests, then you should also install ca-certificates.

I do. They work now, but they are local. I presume it's for external ones? For alpine it enough just to install ca-certificates without any version?

Tnanks!

[vitoyucepi]

ca-certificates is the list of trusted root and intermediate certificates. You need them to validate secure connections.
You may want to pin the version, but it's not necessary.

[gAlleb]

I see. Thanks so much! Gonna dig further!

[Moonbase59]

@gAlleb Remember you’ll need an ffmpeg with libswresample for cue_file to work.

[vitoyucepi]

To use liquidsoap with alpine:3.19, you need to rebuild the binary.

• https://pkgs.alpinelinux.org/contents?file=&path=&name=ffmpeg-libswresample&branch=v3.19&arch=x86_64
• https://pkgs.alpinelinux.org/contents?file=&path=&name=ffmpeg-libswresample&branch=edge&&arch=x86_64

[gAlleb]

So it won't work with edge?

[vitoyucepi]

Without rebuilding it will not work with 3.19.
The main problem with alpine:edge is the rolling release. Ref: #3875.

[gAlleb]

Hi, @vitoyucepi. So I found another use for Docker :) and compiled centrifugo binary inside the container

FROM golang:1.22-bookworm 

RUN apt-get update \
    && apt-get install -y --no-install-recommends openssl git

RUN go install github.com/jwilder/dockerize@v0.6.1

RUN go install github.com/aptible/supercronic@v0.2.28

RUN mkdir -p /tmp/centrifugo \
    && cd /tmp/centrifugo \
    && git clone https://github.com/centrifugal/centrifugo.git . \
    && git checkout 5.4.0_dev \
    && go build \
    && mv ./centrifugo /go/bin/centrifugo

It's nice so you don't have to install all the packages on your system and increase number of trash. Then I got a 60MB binary and removed 2GB! container.

Binary is working fine. So I decided to make a docker image with it to test (and maybe accommodating it within LS Docker). It is straightforward and I've made the same steps as guys at centrifugo do (alike their docker repository):

FROM alpine:3.19

RUN apk --no-cache upgrade && apk --no-cache add ca-certificates  

COPY centrifugo /usr/local/bin/centrifugo

WORKDIR /centrifugo

CMD ["centrifugo"]

But It refuses to work (and I have tried even pulling their official binary and building again with it). Just doesn't want to start:

exec /usr/local/bin/centrifugo: no such file or directory

That's what I got. I've tried lot's of options, with x, a+x, non of that too — doesn't work. Any insights on that? Probably I'm doing something wrong. Thanks!

[vitoyucepi]

Why not just use the prebuild image https://hub.docker.com/r/centrifugo/centrifugo?

RUN apk --no-cache upgrade

I can't recommend this because it may have unknown side effects.

FROM golang:1.22-bookworm
FROM alpine:3.19

I'm not 100% sure about go, but here are my thoughts.
The go binaries built in Debian expect glibc. Alpine can only provide musl.
Either use Alpine in both cases, or CGO_ENABLED=0.

[gAlleb]

Why not just use the prebuild image https://hub.docker.com/r/centrifugo/centrifugo?
RUN apk --no-cache upgrade

It's an unreleased version with some new features like cached recovery. So no need for on connect backend proxy server (#3782 (comment)). Last event is sent on connect from history with just couple of lines added to centrifugo config.

I'm not 100% sure about go, but here are my thoughts.
The go binaries built in Debian expect glibc. Alpine can only provide musl.
Either use Alpine in both cases, or CGO_ENABLED=0.

I don't thinks that this is related. Because I've tried the following:

1. Pull official image
2. Extract centrifugo binary
3. Make new image with that binary with the same OS version and steps as per https://github.com/centrifugal/centrifugo/blob/master/Dockerfile
4. Got the same results: exec /usr/local/bin/centrifugo: no such file or directory

Probably my mistake somewhere and I am missing something.

[vitoyucepi]

# FROM golang:1.22.3-alpine3.20 as build
FROM golang:1.22.3-bookworm as build

# RUN apk add git
RUN set -eux; \
      apt-get update; \
      apt-get install --no-install-recommends git;

RUN git clone https://github.com/centrifugal/centrifugo.git -b 5.4.0_dev --depth 1

WORKDIR /go/centrifugo

# RUN go build
RUN CGO_ENABLED=0 go build

FROM alpine:3.20

COPY --from=build /go/centrifugo/centrifugo /usr/bin
RUN centrifugo version

[gAlleb]

That is great. Well, live and learn. Thank you very much, Vito.