smallwebwaf starts with SWWAF_STATE_DIR given as a file on a new volume (closes #137)

The run script gave ${SWWAF_STATE_DIR:-/var/lib/smallwebwaf} to the
smallwebwaf user and never read SWWAF_STATE_DIR_FILE, so a new volume
at the directory that file names stayed root's. The run script now
takes the setting from the variable or the file, and changes the owner
only when it is the absolute path of a directory that exists;
otherwise it starts smallwebwaf, which stops with its message naming
the setting. A chown that fails, as on a read-only volume, no longer
ends the run script. script/example-app, and its entry in README.md,
gain two steps: a container on such a volume becomes healthy, and a
missing state directory reaches smallwebwaf's message.

Model: opus-5-5

script/example-app

@@ -5,12 +5,15 @@
 # served through smallwebwaf, that a second one in a minute bans the
 # client, that a probe for /.env bans another client, which its next
 # request bans for good, that `sv stop` stops smallwebwaf in order, that
-# `docker stop` stops the container without having to kill it, and that
-# a new container on the same volume still refuses the banned client. The
+# `docker stop` stops the container without having to kill it, that a
+# new container on the same volume still refuses the banned client, that
+# a container with its state files on a new volume mounted at the
+# directory SWWAF_STATE_DIR_FILE names becomes healthy, and that one whose
+# SWWAF_STATE_DIR does not exist logs smallwebwaf's message about it. The
 # containers run with SWWAF_LOOKUP_SOURCE=off, so that no address is sent
-# to GeoJS. The containers, the volume and both images are removed however
-# the script ends. Building the app needs network access, for nixpkgs'
-# binary cache. script/check does not run this.
+# to GeoJS. The containers, the volumes and both images are removed
+# however the script ends. Building the app needs network access, for
+# nixpkgs' binary cache. script/check does not run this.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -23,10 +26,15 @@ IMAGE="$NAME-base"
 APP_IMAGE="$NAME-app"
 CONTAINER="$NAME"
 VOLUME="$NAME-state"
+# The volumes of the container whose state directory SWWAF_STATE_DIR_FILE
+# names: its state files, and the file that names their directory.
+MOVED_VOLUME="$NAME-moved-state"
+SETTINGS_VOLUME="$NAME-settings"
 
 cleanup() {
     docker rm --force "$CONTAINER" >/dev/null 2>&1 || true
-    docker volume rm --force "$VOLUME" >/dev/null 2>&1 || true
+    docker volume rm --force "$VOLUME" "$MOVED_VOLUME" "$SETTINGS_VOLUME" \
+        >/dev/null 2>&1 || true
     docker rmi --force "$APP_IMAGE" "$IMAGE" >/dev/null 2>&1 || true
 }
 
@@ -76,6 +84,27 @@ start_container() {
     address="$(docker port "$CONTAINER" 8080/tcp)"
 }
 
+# start_moved_container: run the app's container with the state files on
+# a new volume at /srv/state, which SWWAF_STATE_DIR_FILE names in a file
+# only the smallwebwaf user can read, as under "Settings given as files"
+# in README.md, and wait until it is healthy. smallwebwaf can write the
+# new volume only once the run script has given it to that user.
+start_moved_container() {
+    docker volume create "$MOVED_VOLUME" >/dev/null
+    docker volume create "$SETTINGS_VOLUME" >/dev/null
+    docker run --rm --volume "$SETTINGS_VOLUME:/settings" \
+        --entrypoint bash "$IMAGE" -c 'echo /srv/state > /settings/state-dir &&
+            chown smallwebwaf:smallwebwaf /settings/state-dir &&
+            chmod 0400 /settings/state-dir'
+    docker run --detach --name "$CONTAINER" \
+        --volume "$MOVED_VOLUME:/srv/state" \
+        --volume "$SETTINGS_VOLUME:/etc/smallwebwaf/settings:ro" \
+        --env SWWAF_STATE_DIR_FILE=/etc/smallwebwaf/settings/state-dir \
+        --env SWWAF_LOOKUP_SOURCE=off \
+        "$APP_IMAGE" >/dev/null
+    wait_for "the health check did not pass" healthy
+}
+
 # refused: a request to the container gets 403, SWWAF_BAN_RESPONSE's
 # default.
 refused() {
@@ -140,6 +169,20 @@ main() {
     wait_for "smallwebwaf logged no request refused under the ban" \
         logged '"action":"banned"'
     echo "example-app: a new container on the same volume keeps the ban"
+
+    docker rm --force "$CONTAINER" >/dev/null
+    start_moved_container
+    echo "example-app: the run script gives the state files' directory named" \
+        "by SWWAF_STATE_DIR_FILE to the smallwebwaf user"
+
+    docker rm --force "$CONTAINER" >/dev/null
+    docker run --detach --name "$CONTAINER" \
+        --env SWWAF_STATE_DIR=/srv/missing \
+        --env SWWAF_LOOKUP_SOURCE=off \
+        "$APP_IMAGE" >/dev/null
+    wait_for "smallwebwaf did not report the missing state directory" \
+        logged "SWWAF_STATE_DIR cannot be written"
+    echo "example-app: smallwebwaf reports a state directory that does not exist"
 }
 
 main "$@"