Set UPAAS_PORT as well as PORT in docker-compose.yml (closes #230)

upaas reads UPAAS_PORT before PORT, so a UPAAS_PORT line in .env made it
listen on another port than the one the compose file's port mapping and
healthcheck use, and the container never became healthy. The compose file
now sets both to 8080, and its comment and the README's Docker Compose
section say that both are set.

Model: opus-5-5

README.md

@@ -192,16 +192,23 @@ This ensures the main branch always contains clean, tested, working code.
 Environment variables:
 
 | Variable                 | Description                                                                                                                                                                                              | Default                                           |
-| ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------- |
+| ------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------- |
-| `PORT`                 | HTTP listen port                                                                                                                                                       | 8080                                                     |
+| `PORT`                   | HTTP listen port. `UPAAS_PORT` is also read and wins when both are set.                                                                                                                                  | 8080                                              |
-| `UPAAS_DATA_DIR`       | Data directory for SQLite and keys                                                                                                                                     | `./data` (local dev only — use absolute path for Docker) |
+| `UPAAS_DATA_DIR`         | Directory for the SQLite database, session key, builds and deployment logs. Deploys need it to be an absolute path unless `UPAAS_HOST_DATA_DIR` is set.                                                  | `./data` (the Docker image sets `/var/lib/upaas`) |
-| `UPAAS_HOST_DATA_DIR`  | Host path for DATA_DIR (when running in container)                                                                                                                     | _(none — must be set to an absolute path)_               |
+| `UPAAS_HOST_DATA_DIR`    | Host path of `UPAAS_DATA_DIR`, needed when upaas runs in a container so the bind mounts it passes to Docker point at the right host directory. When set, it must be absolute, or upaas refuses to start. | the value of `UPAAS_DATA_DIR`                     |
-| `UPAAS_DOCKER_HOST`    | Docker socket path                                                                                                                                                     | unix:///var/run/docker.sock                              |
+| `UPAAS_DOCKER_HOST`      | Docker daemon address                                                                                                                                                                                    | unix:///var/run/docker.sock                       |
 | `UPAAS_PLAINTEXT_HTTP`   | Set when µPaaS is reached over plain HTTP (no TLS-terminating proxy in front) so CSRF origin checks use `http://`. Leave unset behind a TLS-terminating reverse proxy.                                   | false                                             |
-| `DEBUG`                | Enable debug logging                                                                                                                                                   | false                                                    |
+| `UPAAS_DEBUG`            | Enable debug logging. Also sends the session cookie without the `Secure` flag.                                                                                                                           | false                                             |
-| `SENTRY_DSN`           | Sentry error reporting DSN                                                                                                                                             | ""                                                       |
+| `UPAAS_SENTRY_DSN`       | Read but not used: upaas sends nothing to Sentry                                                                                                                                                         | ""                                                |
-| `METRICS_USERNAME`     | Basic auth for /metrics                                                                                                                                                | ""                                                       |
+| `UPAAS_METRICS_USERNAME` | When set, `/metrics` is served behind basic auth with this username. When unset, there is no `/metrics`.                                                                                                 | ""                                                |
-| `METRICS_PASSWORD`     | Basic auth for /metrics                                                                                                                                                | ""                                                       |
+| `UPAAS_METRICS_PASSWORD` | Basic auth password for `/metrics`                                                                                                                                                                       | ""                                                |
+| `UPAAS_MAINTENANCE_MODE` | Only shown as `maintenanceMode` in the `/health` response; it blocks nothing                                                                                                                             | false                                             |
+| `UPAAS_SESSION_SECRET`   | Key that signs the session and CSRF cookies. When unset, a random key is generated once and kept in `$UPAAS_DATA_DIR/session.key`.                                                                       | ""                                                |
+| `UPAAS_CORS_ORIGINS`     | Comma-separated origins allowed to make cross-origin requests with cookies. When unset, no CORS headers are sent.                                                                                        | ""                                                |
+
+The Docker client also reads the standard `DOCKER_API_VERSION`,
+`DOCKER_CERT_PATH` and `DOCKER_TLS_VERIFY` variables; `UPAAS_DOCKER_HOST`, which
+has a default, always overrides `DOCKER_HOST`.
 
 ## Running with Docker
 
@@ -229,15 +236,18 @@ settings from a `.env` file next to it, which needs at least:
 HOST_DATA_DIR=/srv/upaas/data
 ```
 
-Other settings from [Configuration](#configuration) go in the same file. Then
+Other settings from [Configuration](#configuration) go in the same file, except
-run `docker compose up -d` from the repo root; `docker compose ps` shows the
+`PORT`, `UPAAS_PORT` and `UPAAS_DATA_DIR`: the compose file sets both port
+settings to 8080 and `UPAAS_DATA_DIR` to `/var/lib/upaas`, overriding `.env`, to
+match its port mapping, healthcheck and data directory mount. Then run
+`docker compose up -d` from the repo root; `docker compose ps` shows the
 container as healthy once `/health` answers.
 
 **Important**: `HOST_DATA_DIR` **must** be an **absolute path** on the host. It
 is bind-mounted into the container and passed as `UPAAS_HOST_DATA_DIR` so that
-Docker bind mounts during builds resolve correctly. Relative paths (e.g.
+Docker bind mounts during builds resolve correctly, because the Docker daemon
-`./data`) will break container builds because the Docker daemon resolves paths
+resolves paths on the host, not in the container. upaas refuses to start when
-relative to the host, not the container.
+`UPAAS_HOST_DATA_DIR` is a relative path such as `./data`.
 
 The port is published on `127.0.0.1:8080` only, for a TLS-terminating reverse
 proxy in front of it. Leave `UPAAS_PLAINTEXT_HTTP` unset behind that proxy.

TODO.md

@@ -20,10 +20,28 @@ regress.
 
 # Completed Steps
 
+- 2026-09-29: `docker-compose.yml` now sets `UPAAS_PORT` to 8080 as well as
+  `PORT`, since upaas reads `UPAAS_PORT` first and a `UPAAS_PORT` in `.env` made
+  it listen away from the port mapping and healthcheck; the README's Compose
+  section names both (#230).
+
+- 2026-09-29: The README Configuration table now lists every setting upaas
+  reads, adding `UPAAS_MAINTENANCE_MODE`, `UPAAS_SESSION_SECRET` and
+  `UPAAS_CORS_ORIGINS`, and gives the real default and effect of each:
+  `UPAAS_PORT` wins over `PORT`, `UPAAS_HOST_DATA_DIR` falls back to
+  `UPAAS_DATA_DIR`, `UPAAS_DEBUG` drops the session cookie's `Secure` flag, and
+  `UPAAS_SENTRY_DSN` is not used (#229).
+
+- 2026-09-28: The README Configuration table now names `UPAAS_DEBUG`,
+  `UPAAS_SENTRY_DSN`, `UPAAS_METRICS_USERNAME` and `UPAAS_METRICS_PASSWORD`, the
+  names upaas actually reads (the unprefixed names it listed were ignored), and
+  the `UPAAS_HOST_DATA_DIR` row refers to `UPAAS_DATA_DIR` (#224).
+
 - 2026-09-28: Added `docker-compose.yml` for deploying upaas: settings from
   `.env`, the port published on `127.0.0.1` only for a TLS proxy in front, and a
   healthcheck against `/health`; the README's plain-HTTP Compose example is
-  replaced by a short deploy section (#223).
+  replaced by a short deploy section. upaas now refuses to start when
+  `UPAAS_HOST_DATA_DIR` is set to a relative path (#223).
 
 - 2026-09-23: Apps are now built with BuildKit, so the stages of a multi-stage
   build stay in Docker's size-limited build cache instead of piling up as

docker-compose.yml

@@ -7,6 +7,14 @@ services:
     # Every line of .env is passed to upaas as an environment variable.
     env_file: .env
     environment:
+      # Override any PORT or UPAAS_PORT in .env, so upaas listens where the
+      # port mapping and healthcheck below expect it. Both are set because
+      # upaas reads UPAAS_PORT first.
+      PORT: "8080"
+      UPAAS_PORT: "8080"
+      # Overrides any UPAAS_DATA_DIR in .env, so the database stays on the
+      # HOST_DATA_DIR mount below instead of inside the container.
+      UPAAS_DATA_DIR: /var/lib/upaas
       # The Docker daemon resolves app bind mounts on the host, so upaas must
       # know the host path of its data directory.
       UPAAS_HOST_DATA_DIR: ${HOST_DATA_DIR:?set HOST_DATA_DIR in .env to an absolute host path}

internal/config/config.go

@@ -32,6 +32,12 @@ const (
 	filePermissions = 0o600
 )
 
+// errHostDataDirNotAbsolute is returned when UPAAS_HOST_DATA_DIR is set to a
+// relative path, which the Docker daemon cannot resolve for app bind mounts.
+var errHostDataDirNotAbsolute = errors.New(
+	"UPAAS_HOST_DATA_DIR must be an absolute path",
+)
+
 // Params contains dependencies for Config.
 type Params struct {
 	fx.In
@@ -124,6 +130,10 @@ func buildConfig(log *slog.Logger, params *Params) (*Config, error) {
 	dataDir := viper.GetString("DATA_DIR")
 	hostDataDir := viper.GetString("HOST_DATA_DIR")
 
+	if hostDataDir != "" && !filepath.IsAbs(hostDataDir) {
+		return nil, fmt.Errorf("%w, got %q", errHostDataDirNotAbsolute, hostDataDir)
+	}
+
 	if hostDataDir == "" {
 		hostDataDir = dataDir
 	}

internal/config/config_test.go

@@ -0,0 +1,33 @@
+package config //nolint:testpackage // tests unexported buildConfig
+
+import (
+	"errors"
+	"log/slog"
+	"testing"
+)
+
+func TestBuildConfigRejectsRelativeHostDataDir(t *testing.T) {
+	t.Setenv("UPAAS_HOST_DATA_DIR", "./data")
+	setupViper("upaas")
+
+	_, err := buildConfig(slog.Default(), &Params{})
+	if !errors.Is(err, errHostDataDirNotAbsolute) {
+		t.Fatalf("expected errHostDataDirNotAbsolute, got %v", err)
+	}
+}
+
+func TestBuildConfigHostDataDirDefaultsToDataDir(t *testing.T) {
+	t.Setenv("UPAAS_DATA_DIR", "./data")
+	t.Setenv("UPAAS_HOST_DATA_DIR", "")
+	t.Setenv("UPAAS_SESSION_SECRET", "test-secret")
+	setupViper("upaas")
+
+	cfg, err := buildConfig(slog.Default(), &Params{})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if cfg.HostDataDir != "./data" {
+		t.Errorf("expected HostDataDir ./data, got %q", cfg.HostDataDir)
+	}
+}