Let's get started

Author: jkmassel

.buildkite/pipeline.yml

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+steps:
+  - label: ":shell: Lint (Shellcheck)"
+    plugins:
+      shellcheck#v1.1.2:
+        files: hooks/**
+
+  - label: ":sparkles: Lint (Buildkite Plugin Linter)"
+    plugins:
+      plugin-linter#v2.0.0:
+        id: automattic/bash-cache
+
+  - label: ":docker: Test"
+    plugins:
+      docker-compose#v3.7.0:
+        run: tests

README.md

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+# Bash Cache Buildkite Plugin
+
+A caching plugin that can be invoked from your build script
+
+## Example
+
+For a directory structure that looks like:
+
+```
+my-project/
+├── node_modules/
+├── package.json
+├── package-lock.json
+
+```
+
+Add the following to your `pipeline.yml`:
+
+
+```yml
+steps:
+  - command: |
+      # To persist the cache
+      save_cache node_modules/ $(hash_file package-lock.json)
+
+      # To restore the cache, if present
+      restore_cache $(hash_file package-lock.json)
+
+    plugins:
+      - automattic/bash-cache#v1.0.0
+```
+
+## Configuration
+
+There are no configuration options for this plugin
+
+## Developing
+
+To run the linter and tests:
+
+```shell
+docker-compose run --rm lint
+docker-compose run --rm tests
+```
+
+## Contributing
+
+1. Fork the repo
+2. Make the changes
+3. Run the tests
+4. Commit and push your changes
+5. Send a pull request

bin/hash_directory

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+#!/bin/bash
+
+set -e
+
+DIRECTORY_PATH=$1
+
+if [ -z "$1" ]; then
+	echo "You must pass a directory name to hash"
+	return 1
+fi
+
+# - Find all files in the given directory
+# - Run `sha256sum` on each file found – the `+` flag does it in parallel for a huge speed boost.
+# - Sort the files by filename for deterministic hashing
+# - Take the hash of all of the output hashes (and file paths)
+find "$DIRECTORY_PATH" -type f -exec shasum -a 256 "{}" \+ | sort -k 2 | shasum -a 256 | cut -f1 -d " "

bin/hash_file

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+#!/bin/bash
+
+set -e
+
+if [ -z "$1" ]; then
+	echo "You must pass a filename to hash"
+	return 1
+fi
+
+shasum -a 256 "$1" | cut -f1 -d " "

bin/restore_cache

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+#!/bin/bash
+
+set -e
+
+CACHE_KEY=$1
+
+if [ -z "$CACHE_BUCKET_NAME" ]; then
+	echo "⛔Unable to save file to cache – no \$CACHE_BUCKET_NAME is set"
+	return 1
+fi
+
+if aws s3api head-object --bucket "$CACHE_BUCKET_NAME" --key "$CACHE_KEY" > /dev/null 2>&1; then
+	echo "Restoring cache entry $CACHE_KEY"
+
+	echo "	Downloading"
+	aws s3 cp "s3://a8c-ci-cache/$CACHE_KEY" "$CACHE_KEY" --quiet
+
+	echo "	Decompressing"
+	tar -xf "$CACHE_KEY"
+
+	echo "	Cleaning Up"
+	rm "$CACHE_KEY"
+else
+	echo "No cache entry found"
+fi

bin/save_cache

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+#!/bin/bash
+
+set -e
+
+CACHE_FILE=$1
+CACHE_KEY=$2
+
+if [ -z "$CACHE_FILE" ]; then
+	echo "You must pass the file or directory you want to be cached"
+	return 1
+fi
+
+# We can automatically derive a cache key if one isn't provided
+if [ -z "$CACHE_KEY" ]; then
+	echo "No cache key provided – automatically deriving one:"
+
+	# if the $CACHE_FILE is a directory, derived the key from the hash of all files within it
+	if [[ -d $CACHE_FILE ]]; then
+		CACHE_KEY=$(hash_directory "$CACHE_FILE")
+		echo "	'$CACHE_FILE' is a directory with the hash $CACHE_KEY"
+
+	# if the $CACHE_FILE is a regular file, derive the key from the file's hash
+	elif [[ -f $CACHE_FILE ]]; then  
+		CACHE_KEY=$(hash_file "$CACHE_FILE")
+		echo "	'$CACHE_FILE' is a file with the hash $CACHE_KEY"
+	fi
+fi
+
+if [ -z "$CACHE_BUCKET_NAME" ]; then
+	if [ -z "$BUILDKITE_PLUGIN_BASH_CACHE_BUCKET" ]; then
+		printenv | grep buildkite
+		echo "Reading bucket name from 'BUILDKITE_PLUGIN_BASH_CACHE_BUCKET'"
+		CACHE_BUCKET_NAME="$BUILDKITE_PLUGIN_BASH_CACHE_BUCKET"
+	else
+		echo "⛔Unable to save file to cache – no \$CACHE_BUCKET_NAME is set"
+		return 1
+	fi
+fi
+
+if ! aws s3api head-object --bucket "$CACHE_BUCKET_NAME" --key "$CACHE_KEY" > /dev/null 2>&1; then
+	echo "No existing cache entry for $CACHE_KEY – storing in cache"
+
+	echo "	Compressing"
+	tar -czf "$CACHE_KEY" "$CACHE_FILE"
+
+	echo "	Uploading"
+	aws s3 cp "$CACHE_KEY" "s3://$CACHE_BUCKET_NAME/$CACHE_KEY" --quiet
+
+	echo "	Cleaning Up"
+	rm "$CACHE_KEY"
+else
+	echo "This file is already cached – skipping upload"
+fi

docker-compose.yml

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+services:
+  tests:
+    image: buildkite/plugin-tester
+    volumes:
+      - ".:/plugin:ro"
+  lint:
+    image: buildkite/plugin-linter
+    command: ['--id', 'automattic/bash-cache']
+    volumes:
+      - ".:/plugin:ro"

hooks/environment

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+#!/bin/bash
+
+# The `pre-command` hook will run just before your build command runs
+
+# Note that as the script is sourced not run directly, the shebang line will be ignored
+# See https://buildkite.com/docs/agent/v3/hooks#creating-hook-scripts
+
+set -e
+
+HOOKS_ROOT=$( dirname "${BASH_SOURCE[0]}" )
+PLUGIN_ROOT=$( dirname "$HOOKS_ROOT" )
+PLUGIN_BIN="$PLUGIN_ROOT/bin"
+
+export PATH="$PATH:$PLUGIN_BIN"
+
+echo "~~~ :file_cabinet: Loaded Caching Plugin"

plugin.yml

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+name: Bash Cache
+description: Caching operations inside your build script
+author: https://github.com/automattic
+requirements: ['awscli']
+configuration:
+  properties:
+    bucket:
+      type: string
+  additionalProperties: false

test.sh

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+#!/bin/bash
+
+docker-compose run --rm lint
+docker-compose run --rm tests
+
+# Test hooks
+shellcheck hooks/*