Add install, build and packages hooks.

* Add install, build and packages hooks.

Issue: #6

.gitignore

@@ -1,2 +1,3 @@
-tests/test-func/test-out.log
-target
+tests/test-*/test-out.log
+target
+.DS_Store

README.md

@@ -54,6 +54,18 @@ $ docker run --rm \
     softprops/lambda-rust
 ```
 
+## ⚓ using hooks
+
+If you want to customize certain parts of the build process, you can leverage hooks that this image provides.
+Hooks are just shell scripts that are invoked in a specific order, so you can customize the process as you wish. The following hooks exist:
+* `install`: run before `cargo build` - useful for installing native dependencies on the lambda environment
+* `build`: run after `cargo build`, but before packaging the executable into a zip - useful when modifying the executable after compilation
+* `package`: run after packaging the executable into a zip - useful for adding extra files into the zip file
+
+The hooks' names are predefined and must be placed in a directory `.lambda-rust` in the project root. 
+
+You can take a look at an example [here](./tests/test-func-with-hooks).
+
 ## 🤸🤸 usage via cargo aws-lambda subcommand
 
 If you want to set up ad hoc lambda functions or have another reason to not to go with full blown devops orchestration tools,

build.sh

@@ -2,6 +2,11 @@
 # build and pack a rust lambda library
 # https://aws.amazon.com/blogs/opensource/rust-runtime-for-aws-lambda/
 
+HOOKS_DIR="$PWD/.lambda-rust"
+INSTALL_HOOK="install"
+BUILD_HOOK="build"
+PACKAGE_HOOK="package"
+
 set -eo pipefail
 mkdir -p target/lambda
 export PROFILE=${PROFILE:-release}
@@ -18,6 +23,13 @@ export CARGO_TARGET_DIR=$PWD/target/lambda
     if [[ $# -gt 0 ]]; then
         yum install -y "$@"
     fi
+
+    if test -f "$HOOKS_DIR/$INSTALL_HOOK"; then
+        echo "Running install hook"
+        /bin/bash "$HOOKS_DIR/$INSTALL_HOOK"
+        echo "Install hook ran successfully"
+    fi
+
     # source cargo
     . $HOME/.cargo/env
     # cargo only supports --release flag for release
@@ -27,6 +39,12 @@ export CARGO_TARGET_DIR=$PWD/target/lambda
     else
         cargo build ${CARGO_FLAGS:-}
     fi
+
+    if test -f "$HOOKS_DIR/$BUILD_HOOK"; then
+        echo "Running build hook"
+        /bin/bash "$HOOKS_DIR/$BUILD_HOOK"
+        echo "Build hook ran successfully"
+    fi
 ) 1>&2
 
 function package() {
@@ -45,6 +63,12 @@ function package() {
     fi
     zip "$file.zip" bootstrap
     rm bootstrap
+
+    if test -f "$HOOKS_DIR/$PACKAGE_HOOK"; then
+        echo "Running package hook"
+        /bin/bash "$HOOKS_DIR/$PACKAGE_HOOK" $file
+        echo "Package hook ran successfully"
+    fi
 }
 
 cd "${CARGO_TARGET_DIR}/${TARGET_PROFILE}"

tests/test-func-with-hooks/.lambda-rust/build

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+echo "build hook called"
+echo -n 'build,' >> /code/output.log

tests/test-func-with-hooks/.lambda-rust/install

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+echo "install hook called"
+rm /code/output.log
+echo -n 'install,' >> /code/output.log

tests/test-func-with-hooks/.lambda-rust/package

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+echo "package hook called"
+echo -n 'package' >> /code/output.log
+zip -j "$1.zip" /code/output.log