Elixir on Containers

.｡oO(さっちゃんですよヾ(〃l _ l)ﾉﾞ☆)

Container is good, because: It gives an abstract of processes with environments. It's easy to deploy.

I'm using container for Elixir server @ dev, test & prod. A little bit stateful WebSocket servers. Umbrella Related tools: Distillery, Dialyzer, docker‑compose, Kubernetes.

Containers for local dev

Why use containers for local dev? Use the same env between Alchemist team members. Use the same env between non‑Alchemist team members. (Rubyist, frontend enginier, etc.) Use the near env between dev, test & prod.

I maintain Docker images that fixes both Erlang & Elixir ver.

Work with the team & CI (Continuous Integration).

My application have some umbrellas. apps/ app_a/ app_b/

Dockerfile (deps.compile & dialyzer ‑‑plt) FROM nesachirou/elixir:1.8_erl21 SHELL ["/bin/ash", "-ex", "-o", "pipefail", "-c"] RUN apk add --no-cache -t .build-deps \ ～ \ git \ && rm -rf /var/cache/apk/* WORKDIR /var/www VOLUME /var/www COPY mix.exs mix.lock ./ COPY apps/app_a/mix.exs apps/app_a/ COPY apps/app_b/mix.exs apps/app_b/ RUN mix "do" deps.get, deps.compile \ && MIX_ENV="test" mix deps.compile \ && mix dialyzer --plt \ && mv _build deps /tmp RUN apk add --no-cache -t .runtime-deps \ inotify-tools \ rsync \ && rm -rf /var/cache/apk/* EXPOSE 4000 4001 CMD ["./entrypoint.sh"]

entrypoint.sh #!/bin/sh -eux # shellcheck shell=dash if test "$(stat /.dockerenv > /dev/null || echo $?)" ; then : "Outside Docker" mix "do" deps.get, compile else : "Inside Docker" rsync -au /tmp/_build /tmp/deps . mix "do" deps.get, compile fi elixir --name [email protected] --cookie example -S mix phx.server

docker-compose.yml --- version: "3" services: example: image: example.docker.registry/example/example:latest depends_on: [example-src] logging: options: max-size: "100m" max-file: "2" ports: - 4000:4000 - 4001:4001 volumes: - example-src:/var/www ～

docker-compose.override.yml --- version: "3" services: example: build: context: . dockerfile: Dockerfiles/Dockerfile.dev docker-compose build --pull --force-rm docker-compose push

docker‑sync http://docker‑sync.io/ Docker (for MacOS) is too slow in it's file IO between containers & the host. docker‑sync solves this, but troublesome. I do a little bit different way (unison + rsync).

docker-compose.yml ～ example-src: image: eugenmayer/unison:2.51.2.1 environment: APP_VOLUME: /app_sync HOST_VOLUME: /host_sync TZ: Asia/Tokyo UNISON_ARGS: | -debug default -ignore 'Name .git/*' -ignore 'Name _build/*' \ -ignore 'Name deps/*' -prefer /host_sync -numericids -auto -batch UNISON_DEST: /app_sync UNISON_SRC: /host_sync UNISON_WATCH_ARGS: -repeat watch volumes: - ../example:/host_sync:cached - example-src:/app_sync volumes: example-src:

precopy_appsync #!/bin/bash -eux rsync -auv \ --delete \ --exclude='.git/*' --exclude='_build/*' --exclude='deps/*' \ /host_sync/ /app_sync docker-compose -f example/docker-compose.yml stop example-src docker-compose -f example/docker-compose.yml run --rm --no-deps example-src \ /host_sync/tools/precopy_appsync docker-compose -f example/docker-compose.yml start example-src

Testing container image yamllint https://github.com/adrienverge/yamllint hadolint https://github.com/hadolint/hadolint container‑structure‑test https://github.com/GoogleContainerTools/container‑ structure‑test

Containers for prod

Work with CD (Continuous Delivery).

Umbrella apps/ app_a/ app_b/ common/

Distillery https://github.com/bitwalker/distillery {:distillery, "~> 2.0", runtime: false}, No hot code swapping, RollingUpdate.

rel/config.exs ～ environment :prod do set(include_erts: true) set(include_src: false) set(cookie: :" ～") set(vm_args: Path.join("rel", "vm.args.prod")) end release :app_a do set(version: "0.0.1") set(applications: [:app_a, :common, :runtime_tools]) set(commands: [app_terminate: "rel/commands/app_terminate.sh"]) set(overlay_vars: [ ～]) end

rel/commands/app_terminate.sh → ./bin/app_a app_terminate (PreStop hook) #!/bin/bash -eu COOKIE=$(awk '/-setcookie/{print$2}' releases/0.0.1/vm.args) export COOKIE bin/app_a command Elixir.AppA.Command app_terminate AppA.Command defmodule AppA.Command do def app_terminate do :ok = do_rpc(:"[email protected]", :"[email protected]", AppA.AppTerminator, :request_terminate, [], 1_800_000) end defp do_rpc(target_node, node_name, module, fun, args, timeout) do Node.start(node_name) Node.set_cookie(String.to_atom(System.get_env("COOKIE"))) :rpc.call(target_node, module, fun, args, timeout) end end

Dockerfile for app_a (multi stage build) FROM nesachirou/elixir:1.8_erl21 as builder SHELL ["/bin/ash", "-ex", "-o", "pipefail", "-c"] RUN apk add --no-cache -t .build-deps \ build-base \ ～ \ git ARG REVISION ENV MIX_ENV=prod WORKDIR /var/www COPY mix.exs mix.lock ./ COPY apps/app_a/mix.exs apps/app_a/ COPY apps/common/mix.exs apps/common/ RUN mix "do" deps.get --only prod, deps.compile COPY apps/app_a apps/app_a COPY apps/common apps/common COPY config config COPY rel rel # hadolint ignore=DL3003 RUN mix compile \ && mix release --verbose --name=app_a ～

Dockerfile for app_a (multi stage build) ～ FROM alpine:3.9 SHELL ["/bin/ash", "-ex", "-o", "pipefail", "-c"] RUN apk add --no-cache -t .runtime-deps \ bash \ inotify-tools \ openssl \ && rm -rf /var/cache/apk/* WORKDIR /var/www # hadolint ignore=DL3010 COPY --from=builder /var/www/_build/prod/rel/app_a/releases/0.0.1/app_a.tar.gz ./ RUN tar xzf app_a.tar.gz \ && rm -rf app_a.tar.gz EXPOSE 80 4369 CMD ["bin/app_a", "foreground"]

container-structured-test.yml --- schemaVersion: "2.0.0" commandTests: - name: Application meta data command: bin/example args: [describe] expectedOutput: - example-0.0.1 - "Name: [email protected]" - name: libcrypto command: bin/example args: [eval, ":crypto.strong_rand_bytes(8)"] metadataTest: cmd: [bin/example, foreground] exposedPorts: ["80", "4369"] workdir: /var/www