# Can't run Phoenix using docker-compose

**URL:** <https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859>\
**Category:** Questions\
**Tags:** docker, phoenix, deployment, releases\
**Created:** [April 10, 2021, 3:43pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859 "2021-04-10T15:43:23Z")\
**Posts on this page:** 14\
**Page:** 1

<div class="post-metadata">

**Author:** ![fly49](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/f/2acd7d/32.png) [@fly49](https://forum.elixirforum.com/u/fly49)\
**Post date:** [April 10, 2021, 3:43pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/1 "2021-04-10T15:43:24Z")

</div>

Hi, I am trying to get Phoenix app work using containers and elixir releases.

I succeeded to run my app in a single container and connect it to local postgres using dockerfile and command below:

Dockerfile:

```elixir
FROM elixir:1.9.0-alpine AS build

# install build dependencies
RUN apk add --no-cache build-base npm git python

# prepare build dir
WORKDIR /app

# install hex + rebar
RUN mix local.hex --force && \
    mix local.rebar --force

# set build ENV
ENV MIX_ENV=prod

# install mix dependencies
COPY mix.exs mix.lock ./
COPY config config
RUN mix do deps.get, deps.compile

# build assets
COPY assets/package.json assets/package-lock.json ./assets/
RUN npm --prefix ./assets ci --progress=false --no-audit --loglevel=error

COPY priv priv
COPY assets assets
RUN npm run --prefix ./assets deploy
RUN mix phx.digest

# compile and build release
COPY lib lib
# uncomment COPY if rel/ exists
# COPY rel rel
RUN mix do compile, release

# prepare release image
FROM alpine:3.9 AS app
RUN apk add --no-cache openssl ncurses-libs

EXPOSE 4000
ENV PORT=4000 \
    MIX_ENV=prod \
    SHELL=/bin/bash

WORKDIR /app

RUN chown nobody:nobody /app

USER nobody:nobody

COPY --from=build --chown=nobody:nobody /app/_build/prod/rel/myapp ./

ENV HOME=/app

CMD ["bin/myapp", "start"]

```

Commands:

```elixir
docker build -t test .

```

```elixir
docker run \
  --network=host \
  -e DATABASE_URL=postgresql://postgres:postgres@localhost/myapp_dev \
  -e SECRET_KEY_BASE=...some key... \
  -e HOST=localhost \
  test    

```

But when I am trying to up two containers via docker-compose.yml

```elixir
version: '3'

services:
  PostgreSQL:
    image: postgres
    container_name: postgres
    ports:
      - 5433:5432
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_INITDB_ARGS: "--encoding=UTF-8"
    hostname: postgres
    restart: always
    user: root
  elixir:
    build:
      context: .
      dockerfile: Dockerfile
    env_file:
      - .env.list
    ports:
      - 4040:4000
    container_name: elixir
    volumes:
      - .:/app
    depends_on:
      - PostgreSQL

```

.env.list:

```elixir
DATABASE_URL=postgresql://postgres:postgres@postgres/myapp_prod
SECRET_KEY_BASE=... some key...
HOST=localhost

```

I am getting an error:

```elixir
Creating postgres ... done
Creating elixir ... error

ERROR: for elixir Cannot start service elixir: OCI runtime create failed: container_linux.go:367: starting container process caused: exec: "bin/myapp": stat bin/myapp: no such file or directory: unknown
ERROR: Encountered errors while bringing up the project.

```

I suppose that docker-compose should just run elixir container with according dockerfile as just it happens with “docker run …”, but it seems that I get different container which doesn’t have bin/ directory for some reason. Am I missing something?

---

<div class="post-metadata">

**Author:** ![pmangalakader](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/p/bc79bd/32.png) [@pmangalakader](https://forum.elixirforum.com/u/pmangalakader)\
**Post date:** [April 10, 2021, 4:34pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/2 "2021-04-10T16:34:43Z")

</div>

it seems, volume mount for elixir container in the docker-compose overwrites the docker build container files. Try removing the mount and see if that solves the issue.

```elixir
volumes:
      - .:/app
# remove this

```

---

<div class="post-metadata">

**Author:** ![Exadra37](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/exadra37/32/9183_2.png) [@Exadra37](https://forum.elixirforum.com/u/Exadra37)\
**Post date:** [April 10, 2021, 9:37pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/3 "2021-04-10T21:37:27Z")

</div>

> [@fly49](#):
>
> `user: root`

Never use the root user in any docker image, just like you would not use it in a real server.

> [@fly49](#):
>
> ```elixir
> ports:
> - 5433:5432
> 
> ```

The database is open to the internet. You don’t need to expose the ports for the `elixir` service to be able to reach it.

> [@fly49](#):
>
> ` hostname: postgres`

This is not necessary, instead just change the name of the docker-compose service from `PostgreSQL` to `postgres`.

> [@fly49](#):
>
> ```elixir
> ports:
> - 4040:4000
> 
> ```

If is for running in localhost then you need to do it like `127.0.0.1:4040:4000`, otherwise it may be reachable from the internet, unless you have other security measures in place.

The use of `4040:4000` is equivalent to `0.0.0.0:4040:4000`, and `0.0.0.0` means it will be listening in all configured networks on your computer.

> [@fly49](#):
>
> ```elixir
> RUN chown nobody:nobody /app
> 
> USER nobody:nobody
> 
> COPY --from=build --chown=nobody:nobody /app/_build/prod/rel/myapp ./
> 
> ```

It’s unsafe to use the `nobody` user as I report on this [issue](https://github.com/phoenixframework/phoenix/issues/4188) and now being [merged](https://github.com/phoenixframework/phoenix/pull/4257) to the official docs.

---

<div class="post-metadata">

**Author:** ![fly49](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/f/2acd7d/32.png) [@fly49](https://forum.elixirforum.com/u/fly49)\
**Post date:** [April 11, 2021, 10:15am UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/4 "2021-04-11T10:15:24Z")

</div>

@pmangalakader  
Thanks you! It solves the issue!

@Exadra37  
Thank you for detailed response, a lot of useful info for me as for docker beginner.  
Also I took a look at the PR you mentioned and tried to build a fresh image with new dockerfile, but it has this line:

```elixir
# changes to config/runtime.exs don't require recompiling the code
COPY config/runtime.exs config/

```

It seems that “config/runtime.exs” file is not a default thing, at least there is no mentions in docs to create it, and as well I don’t have one.

---

<div class="post-metadata">

**Author:** ![Exadra37](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/exadra37/32/9183_2.png) [@Exadra37](https://forum.elixirforum.com/u/Exadra37)\
**Post date:** [April 11, 2021, 10:38am UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/5 "2021-04-11T10:38:41Z")

</div>

> [@fly49](#):
>
> ```elixir
> # changes to config/runtime.exs don't require recompiling the code
> COPY config/runtime.exs config/
> 
> ```
> 
> It seems that “config/runtime.exs” file is not a default thing, at least there is no mentions in docs to create it, and as well I don’t have one.

Unfortunately it’s not a default.

It was introduced in Elixir 1.11 to solve the configuration issues that have plagued Elixir since the begin.

Think of this file not as runtime but instead as a boot time configuration file, because contrary to what the name `runtime` implies it doesn’t allow to change configuration while your app is running, but it allows you to change configuration every time you boot your app.

In my apps I move all configuration to this file as much as possible. Check the official docs [here](https://hexdocs.pm/mix/Mix.Tasks.Release.html#module-runtime-configuration):

> To enable runtime configuration in your release, all you need to do is to create a file named `config/runtime.exs`:
> 
> ```elixir
> import Config
> config :my_app, :secret_key, System.fetch_env!("MY_APP_SECRET_KEY")
> 
> ```

### Secrets in Releases

For example `prod.secret.exs` isn’t secure to use, because now you have your production secrets inside the release binary and production secrets MUST BE only present in the server running the app, otherwise you risk to leak the secrets in all the places were the release binary is handled. It’s easy to reverse engineer a binary and extract those secrets.

Always require your secrets in `runtime.exs` with the use of environment variables. This approach will keep your production secrets outside the release binary that you have built somewhere else.

---

<div class="post-metadata">

**Author:** ![fly49](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/f/2acd7d/32.png) [@fly49](https://forum.elixirforum.com/u/fly49)\
**Post date:** [April 11, 2021, 3:16pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/6 "2021-04-11T15:16:35Z")

</div>

@Exadra37  
I succeeded to build an image from new [dockerfile](https://github.com/J0/phoenix/blob/j0_fix_deployment_guide/guides/deployment/releases.md), with all boot logic in runtime.exs as you said, but when I try:

```elixir
sudo docker container run --rm -it -p 127.0.0.1:4000:4000 --name my_app elixir/my_app

```

I get

```elixir
mkdir: can't create directory '/home/elixir/app/tmp': Permission denied
ERROR: Cannot start release because it could not write /home/elixir/app/tmp/myapp-0.1.0-20210411150040-8d6a.runtime.config

```

---

<div class="post-metadata">

**Author:** ![Exadra37](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/exadra37/32/9183_2.png) [@Exadra37](https://forum.elixirforum.com/u/Exadra37)\
**Post date:** [April 11, 2021, 4:31pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/7 "2021-04-11T16:31:43Z")

</div>

You need to share the exact dockerfile you are using, otherwise is not possible to understand whats going on.

---

<div class="post-metadata">

**Author:** ![fly49](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/f/2acd7d/32.png) [@fly49](https://forum.elixirforum.com/u/fly49)\
**Post date:** [April 12, 2021, 8:17am UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/8 "2021-04-12T08:17:52Z")

</div>

Exact as [here](https://github.com/J0/phoenix/blob/j0_fix_deployment_guide/guides/deployment/releases.md)

`````elixir
FROM hexpm/elixir:1.11.2-erlang-23.1.2-alpine-3.12.1 as build

# install build dependencies
RUN apk upgrade --no-cache
RUN apk add --no-cache build-base npm git python3 curl

# prepare build dir
WORKDIR /app

# install hex + rebar
RUN mix local.hex --force && \
    mix local.rebar --force

# set build ENV
ARG MIX_ENV="prod"
ENV MIX_ENV="${MIX_ENV}"

# install mix dependencies
COPY mix.exs mix.lock ./
RUN mix deps.get --only $MIX_ENV
RUN mkdir config
# Dependencies sometimes use compile-time configuration. Copying
# these compile-time config files before we compile dependencies
# ensures that any relevant config changes will trigger the dependencies
# to be re-compiled.
COPY config/config.exs config/$MIX_ENV.exs config/
RUN mix deps.compile

# build assets
COPY assets/package.json assets/package-lock.json ./assets/
# install all npm dependencies from scratch
RUN npm --prefix ./assets ci --progress=false --no-audit --loglevel=error

COPY priv priv

# Note: if your project uses a tool like https://purgecss.com/,
# which customizes asset compilation based on what it finds in
# your Elixir templates, you will need to move the asset compilation step
# down so that `lib` is available.
COPY assets assets
# use webpack to compile npm dependencies - https://www.npmjs.com/package/webpack-deploy
RUN npm run --prefix ./assets deploy
RUN mix phx.digest

# compile and build the release
COPY lib lib
RUN mix compile
# changes to config/runtime.exs don't require recompiling the code
COPY config/releases.exs config/
# uncomment COPY if rel/ exists
# COPY rel rel
RUN mix release

# Start a new build stage so that the final image will only contain
# the compiled release and other runtime necessities
FROM alpine:3.12.1 AS app
RUN apk upgrade --no-cache
RUN apk add --no-cache openssl ncurses-libs

ARG MIX_ENV="prod"
ENV USER="elixir"

WORKDIR "/home/${USER}/app"
# Creates an unprivileged user to be used exclusively to run the Phoenix app
RUN \
  addgroup \
   -g 1000 \
   -S "${USER}" \
  && adduser \
   -s /bin/sh \
   -u 1000 \
   -G "${USER}" \
   -h /home/elixir \
   -D "${USER}" \
  && su "${USER}"

# Everything from this line onwards will run in the context of the unprivileged user.
USER "${USER}"

COPY --from=build --chown="${USER}":"${USER}" /app/_build/"${MIX_ENV}"/rel/my_app ./

ENTRYPOINT ["bin/my_app"]

# Usage:
# * build: sudo docker image build -t elixir/my_app .
# * shell: sudo docker container run --rm -it --entrypoint "" -p 127.0.0.1:4000:4000 elixir/my_app sh
# * run: sudo docker container run --rm -it -p 127.0.0.1:4000:4000 --name my_app elixir/my_app
# * exec: sudo docker container exec -it my_app sh
# * logs: sudo docker container logs --follow --tail 100 my_app
#
# Extract the production release to your host machine with:
#
# ```
# mkdir archive
# sudo docker container run --rm -it --entrypoint "" -v "$PWD/archive:/home/phoenix/archive" phoenix/my_app sh -c "tar zcf /home/phoenix/archive/app.tar.gz ."
# ls -al archive
# ````
CMD ["start"]

`````

---

<div class="post-metadata">

**Author:** ![pmangalakader](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/p/bc79bd/32.png) [@pmangalakader](https://forum.elixirforum.com/u/pmangalakader)\
**Post date:** [April 21, 2021, 10:19am UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/9 "2021-04-21T10:19:02Z")

</div>

@fly49 try this, the `chown` worked for me:

```elixir
# Creates an unprivileged user to be used exclusively to run the Phoenix app
RUN addgroup -g 1000 -S "${USER}" && \
    adduser -s /bin/sh -u 1000 -G "${USER}" -h /home/"${USER}" -D "${USER}" && \
    su "${USER}"

RUN chown -R "${USER}:${USER}" "/home/${USER}"
# Everything from this line onwards will run in the context of the unprivileged user.
USER "${USER}"

```

the directory `/home/user`, the `user` directory was owned by `root` and hence, the error occurs.

---

<div class="post-metadata">

**Author:** ![fly49](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/f/2acd7d/32.png) [@fly49](https://forum.elixirforum.com/u/fly49)\
**Post date:** [April 24, 2021, 1:17pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/10 "2021-04-24T13:17:40Z")

</div>

Thank you for the answer! I got suck a the creating and migrating database on containers initialization, tried the trick from [here](https://elixirschool.com/blog/releasing-an-umbrella-app-with-docker-and-mix-release/), but it doesn’t work for me.. Could you recommend me something?

---

<div class="post-metadata">

**Author:** ![pmangalakader](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/p/bc79bd/32.png) [@pmangalakader](https://forum.elixirforum.com/u/pmangalakader)\
**Post date:** [April 24, 2021, 4:26pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/11 "2021-04-24T16:26:58Z")

</div>

@fly49 It’s a straight-forward implementation and I’m using somewhat same pre-start scripts in multiple accounts and works like a charm. Due to NDA constraints, I’m unable to share them with you.

If you could create a new topic and post relevant logs, it would be easier for others also to help you.

---

<div class="post-metadata">

**Author:** ![ambareesha7](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/a/e19adc/32.png) [@ambareesha7](https://forum.elixirforum.com/u/ambareesha7)\
**Post date:** [January 14, 2022, 2:36pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/12 "2022-01-14T14:36:17Z")

</div>

> [@Exadra37](#):
>
> It’s unsafe to use the `nobody` user as I report on this [issue](https://github.com/phoenixframework/phoenix/issues/4188) and now being [merged](https://github.com/phoenixframework/phoenix/pull/4257) to the official docs.

Hey @Exadra37  
As you said it’s merged but changes not working ​  
Today I was preparing for docker deployment and for `mix phx.gen.release --docker` command as suggested on [Phoenix documents](https://hexdocs.pm/phoenix/releases.html#content)  
Used versions to generate: Elixir 1.13, Phoenix 1.6.6  
The `nobody`variable still being used in generated Dockerfile file  
Is it expected behavior or it needs to be reported them on the PR?

---

<div class="post-metadata">

**Author:** ![Exadra37](https://forum.elixirforum.com/user_avatar/forum.elixirforum.com/exadra37/32/9183_2.png) [@Exadra37](https://forum.elixirforum.com/u/Exadra37)\
**Post date:** [February 3, 2022, 10:36pm UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/13 "2022-02-03T22:36:41Z")

</div>

Sorry for the delay in the reply but I have been away from Elixir for some months, does I am not aware how things are related to this.

I would suggest for you to open a new post with reproducible steps to replicate your issue and then people will jump in and try to help/guide you.

---

<div class="post-metadata">

**Author:** ![ambareesha7](https://forum.elixirforum.com/letter_avatar_proxy/v4/letter/a/e19adc/32.png) [@ambareesha7](https://forum.elixirforum.com/u/ambareesha7)\
**Post date:** [February 4, 2022, 1:32am UTC](https://forum.elixirforum.com/t/cant-run-phoenix-using-docker-compose/38859/14 "2022-02-04T01:32:00Z")

</div>

Sure I’ll do it, thank you