Automatic Consul raft discovery and formation

[misterbisson]

No description provided.

[tgross]

why do we need glibc? this feels like something we should be documenting if we need it.

[misterbisson]

Fair question. Honestly, that detail is copied in whole from https://github.com/gliderlabs/docker-consul/blob/legacy/Dockerfile#L6

[misterbisson]

@dekobon this might be a detail of interest to you, given your efforts in this space as well.

[tgross]

I see it -- we're not building consul ourselves and instead we're using a build we're getting from "mitchelh", which was built against libc:

# ldd consul
        linux-vdso.so.1 (0x00007fffffd9c000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f535d222000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f535ce79000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f535d43f000)

(Go binaries aren't always entirely statically linked)

[dekobon]

Interesting. You curl in glibc. Wouldn't it be better to build Consul using Musl?

# Download and install Consul
# We are building it ourselves, because Alpine Linux doesn't use glibc
RUN export GOPATH=/go && \
    apk add --update go git gcc musl-dev make bash && \
    go get github.com/hashicorp/consul && \
    cd $GOPATH/src/github.com/hashicorp/consul && \
    git checkout -q --detach "v$CONSUL_VERSION" && \
    make && \
    mv bin/consul /bin && \
    rm -rf $GOPATH && \
    apk del go git gcc musl-dev make bash && \
    rm -rf /var/cache/apk/* && \
    addgroup consul && \
    adduser -D -G consul consul && \
    mkdir -p /data/consul && \
    chown -R consul:consul /data/consul

Putting aside @tgross 's hate for go get. This would give you a version of Consul that was compiled for the platform. For some reason, I trust a tagged Hashicorp release from github more than I do an entire glibc that I've curled into my environment. In fact, we should probably just create an APK for it and submit it to Alpine.

[misterbisson]

Wouldn't it be better to build Consul using Musl?

we should split the build container out from the container we ship though

Those sound like great ideas for a future version ;-)

[tgross]

It occurs to me that a musl build for something running DNS is something we'd want to test out quite a bit. One of the big behavioral differences between musl and libc is the DNS client library. Not sure if that'll turn out to be relevant for a Go program, but worth checking.

[misterbisson]

Moved to #2

[dekobon]

@tgross This line apk del go git gcc musl-dev make bash && \ mitigates the size of the container because we remove all of the dependencies within the same build step.

@misterbisson Yes, those are great ideas for a future version. Carry on with the good work. 👍

[misterbisson]

Please put all further discussion of an Alpine build in #2

[misterbisson]

I've pushed the image to Docker Hub, so you can test this out with the ./start.sh script provided.

[tgross]

What's this bit for? edit, nevermind. Consul is acting as a recursive server

[tgross]

LGTM