Script to sync Dockerfile and mise.toml

README.md

@@ -25,7 +25,9 @@ firehose/
 ├── blogex/                 # Blogex library (multi-blog engine)
 │   ├── lib/
 │   └── mix.exs
-└── mise.toml               # Runtime versions (Elixir, Erlang, Node)
+├── Dockerfile              # Deploy build; ARG pins must match mise.toml
+├── mise.toml               # Runtime versions (Elixir, Erlang, Node)
+└── scripts/check-pins.sh   # Verifies the pin sync; runs in `make check`
 ```
 
 Two blogs are configured:
@@ -51,6 +53,15 @@ mise install
 
 This installs Elixir, Erlang, and Node at the versions specified in `mise.toml`.
 
+## Toolchain pins
+
+`mise.toml` (local dev toolchain) and the `Dockerfile` `ARG` pins (deploy
+builder image) must agree — local builds and deployed images should run the
+same Elixir/OTP. `make check` runs `scripts/check-pins.sh` to verify this;
+when it reports a MISMATCH, fix the file it names. Upstream drift of these
+pins (newer Elixir/OTP/Debian releases) is reported separately by
+`dokku-updates firehose check` from the dokku-maintenance repo.
+
 ### 2. Start PostgreSQL
 
 You need PostgreSQL running locally with a `postgres` user (password: `postgres`).