diff --git a/fpm/Dockerfile b/fpm/Dockerfile
index cea37c4..7f72370 100644
--- a/fpm/Dockerfile
+++ b/fpm/Dockerfile
@@ -8,6 +8,13 @@ RUN apk --update --no-cache add \
 COPY conf.d/50_fpm.ini /etc/php/conf.d/50_fpm.ini
 COPY php-fpm.conf /etc/php/php-fpm.conf
 
+# Owned by skpr so the live configuration can be replaced in a running
+# container, which is the point of it: the change lands without restarting
+# PHP-FPM.
+RUN mkdir -p /etc/compass && \
+    chown skpr:skpr /etc/compass
+COPY --chown=skpr:skpr compass/config.yml /etc/compass/config.yml
+
 # Ensure the FPM configuration directory is empty.
 # Create an empty file to ensure there are no warnings.
 RUN rm -f /etc/php/php-fpm.d/*.conf && \
@@ -28,15 +35,17 @@ ENV PHP_FPM_PORT=9000 \
     PHP_FPM_MAX_REQUESTS=500 \
     PHP_FPM_REQUEST_TIMEOUT=60
 
+# Startup configuration for the Compass extension.
+# Everything else lives in /etc/compass/config.yml and is reloaded live.
+ENV COMPASS_ENABLED=false \
+    COMPASS_CONFIG_FILE=/etc/compass/config.yml
+
 # Run the test stage to verify the image.
 FROM base AS test
 COPY --from=ghcr.io/goss-org/goss:latest /usr/bin/goss /usr/bin/goss
 ADD goss.yml /tmp/goss.yml
 RUN goss --gossfile /tmp/goss.yml validate
 
-ENV COMPASS_ENABLED=false
-ENV COMPASS_FUNCTION_THRESHOLD=1000000
-
 # The final stage which is used to run the image.
 FROM base AS run
 CMD ["php-fpm", "-F"]
diff --git a/fpm/compass/config.yml b/fpm/compass/config.yml
new file mode 100644
index 0000000..3da225e
--- /dev/null
+++ b/fpm/compass/config.yml
@@ -0,0 +1,10 @@
+# Live configuration for the Compass PHP extension.
+#
+# Running PHP processes pick changes up within five seconds. Nothing needs to be
+# restarted, and nothing here is read while no tracer is attached.
+
+# Only report function calls slower than this, in nanoseconds.
+function_threshold: 1000000
+
+# Stops all probing while it is true, leaving the extension loaded.
+suspend: false
diff --git a/fpm/goss.yml b/fpm/goss.yml
index d8d6863..43226a7 100644
--- a/fpm/goss.yml
+++ b/fpm/goss.yml
@@ -11,3 +11,18 @@ command:
     exit-status: 0
     stdout:
       contain-substring: "compass"
+
+  check-php-compass-config-file:
+    exec: "php -i | grep compass.config_file"
+    exit-status: 0
+    stdout:
+      contain-substring: "/etc/compass/config.yml"
+
+file:
+  /etc/compass/config.yml:
+    exists: true
+    owner: skpr
+    group: skpr
+    contents:
+      - "function_threshold"
+      - "suspend"