update builds to trigger only on relevant changes (#1170)

.github/workflows/docker-publish-cpu.yml

@@ -10,6 +10,20 @@ on:
       #- $default-branch
       - main
       - test
+    # Only build when files that affect the Docker image change.
+    # This avoids expensive 15-25 min builds for docs-only or config-only changes.
+    paths:
+      # Individual files
+      - '.github/workflows/docker-publish-cpu.yml'
+      - 'Cargo.lock'
+      - 'Cargo.toml'
+      - 'build/service_cpu.Dockerfile'
+      # Directories
+      - '.sqlx/**'
+      - '_database/**'
+      - 'crates/**'
+      - 'includes/**'
+      - 'test_data/**'
 env:
   IMAGE_NAME: storyteller-rust
 

build/service_cpu.Dockerfile

@@ -130,53 +130,20 @@ RUN echo "Disk usage at current directory (after tests):"
 RUN pwd
 RUN du -hsc * | sort -hr
 
-# Build all the binaries.
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin storyteller-web
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin seedance2-pro-job
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin worldlabs-job
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin video-thumbnail-job
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin dummy-service
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin analytics-job
-
-RUN SQLX_OFFLINE=true \
-  LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
-  $HOME/.cargo/bin/cargo build \
-  --release \
-  --bin email-sender-job
-
+# Build all the binaries in a single cargo invocation.
+# This lets cargo parallelize shared dependency compilation across all targets,
+# which is significantly faster than building each binary sequentially.
 RUN SQLX_OFFLINE=true \
   LD_LIBRARY_PATH=/usr/lib:${LD_LIBRARY_PATH} \
   $HOME/.cargo/bin/cargo build \
   --release \
+  --bin storyteller-web \
+  --bin seedance2-pro-job \
+  --bin worldlabs-job \
+  --bin video-thumbnail-job \
+  --bin dummy-service \
+  --bin analytics-job \
+  --bin email-sender-job \
   --bin es-update-job
 
 # Print a report on disk space