Fix method to read

Author: aleclerc-cio

README.md

@@ -33,8 +33,12 @@ go install github.com/richardartoul/gobuildcache@latest
 
 ## Usage
 
+You can configure `gobuildcache` by passing arguments directly to the program via `GOCACHEPROG`, or by using environment variables. The CLI argument approach is recommended for CI/CD workflows.
+
+### Using CLI Arguments (Recommended)
+
 ```bash
-export GOCACHEPROG=gobuildcache
+export GOCACHEPROG="gobuildcache --backend=disk"
 go build ./...
 go test ./...
 ```
@@ -43,63 +47,93 @@ By default, `gobuildcache` uses an on-disk cache stored in the OS default tempor
 
 For "production" use-cases in CI, you'll want to configure `gobuildcache` to use S3 Express One Zone, Google Cloud Storage, or a similarly low latency distributed backend.
 
+### Using Environment Variables (Alternative)
+
+You can also configure `gobuildcache` using environment variables:
+
+```bash
+export GOCACHEPROG=gobuildcache
+export GOBUILDCACHE_BACKEND_TYPE=disk
+go build ./...
+go test ./...
+```
+
+**Note:** CLI arguments take precedence over environment variables when both are provided.
+
 ### Using S3
 
+**Using CLI arguments (recommended):**
+
 ```bash
-export GOBUILDCACHE_BACKEND_TYPE=s3
-export GOBUILDCACHE_S3_BUCKET=$BUCKET_NAME
+export GOCACHEPROG="gobuildcache --backend=s3 --s3-bucket=$BUCKET_NAME --s3-prefix=go-build-cache/"
+export AWS_REGION=$BUCKET_REGION
+export AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY
+export AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY
+go build ./...
+go test ./...
 ```
 
-You'll also have to provide AWS credentials. `gobuildcache` embeds the AWS V2 S3 SDK so any method of providing credentials to that library will work, but the simplest is to use environment variables as demonstrated below.
+**Using environment variables:**
 
 ```bash
 export GOCACHEPROG=gobuildcache
 export GOBUILDCACHE_BACKEND_TYPE=s3
 export GOBUILDCACHE_S3_BUCKET=$BUCKET_NAME
+export GOBUILDCACHE_S3_PREFIX=go-build-cache/
 export AWS_REGION=$BUCKET_REGION
 export AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY
 export AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY
 go build ./...
 go test ./...
 ```
 
+You'll need to provide AWS credentials. `gobuildcache` embeds the AWS V2 S3 SDK so any method of providing credentials to that library will work (environment variables, IAM roles, etc.).
+
 > **Note**: All configuration environment variables support both `GOBUILDCACHE_<KEY>` and `<KEY>` forms (e.g., both `GOBUILDCACHE_S3_BUCKET` and `S3_BUCKET` work). The prefixed version takes precedence if both are set. The prefixed form is recommended to avoid conflicts with other tools. If the prefixed variable is set to an empty string, it falls through to the unprefixed version (or default).
 
 ### Using Google Cloud Storage (GCS)
 
+**Using CLI arguments (recommended):**
+
+```bash
+export GOCACHEPROG="gobuildcache --backend=gcs --gcs-bucket=$BUCKET_NAME --gcs-prefix=go-build-cache/"
+go build ./...
+go test ./...
+```
+
+**Using environment variables:**
+
 ```bash
+export GOCACHEPROG=gobuildcache
 export GOBUILDCACHE_BACKEND_TYPE=gcs
 export GOBUILDCACHE_GCS_BUCKET=$BUCKET_NAME
+export GOBUILDCACHE_GCS_PREFIX=go-build-cache/
+go build ./...
+go test ./...
 ```
 
 GCS authentication uses Application Default Credentials. You can provide credentials in one of the following ways:
 
 1. **Service Account JSON file** (recommended for CI):
 ```bash
 export GOOGLE_APPLICATION_CREDENTIALS=/path/to/service-account-key.json
-export GOCACHEPROG=gobuildcache
-export GOBUILDCACHE_BACKEND_TYPE=gcs
-export GOBUILDCACHE_GCS_BUCKET=$BUCKET_NAME
+export GOCACHEPROG="gobuildcache --backend=gcs --gcs-bucket=$BUCKET_NAME"
 go build ./...
 go test ./...
 ```
 
 2. **Metadata service** (when running on GCP):
 ```bash
 # No credentials file needed - uses metadata service automatically
-export GOCACHEPROG=gobuildcache
-export GOBUILDCACHE_BACKEND_TYPE=gcs
-export GOBUILDCACHE_GCS_BUCKET=$BUCKET_NAME
+export GOCACHEPROG="gobuildcache --backend=gcs --gcs-bucket=$BUCKET_NAME"
 go build ./...
 go test ./...
 ```
 
 3. **gcloud CLI credentials** (for local development):
 ```bash
 gcloud auth application-default login
-export GOCACHEPROG=gobuildcache
-export GOBUILDCACHE_BACKEND_TYPE=gcs
-export GOBUILDCACHE_GCS_BUCKET=$BUCKET_NAME
+export GOCACHEPROG="gobuildcache --backend=gcs --gcs-bucket=$BUCKET_NAME"
 go build ./...
 go test ./...
 ```

examples/github_actions_gcs.yml

@@ -0,0 +1,32 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch:
+
+jobs:
+  test:
+    name: Run Tests
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.25'
+          # Use our own cache, obviously.
+          cache: false
+      - name: Install gobuildcache
+        run: go install github.com/richardartoul/gobuildcache@latest
+      - name: Authenticate to Google Cloud
+        uses: google-github-actions/auth@v2
+        with:
+          credentials_json: ${{ secrets.GCP_SA_KEY }}
+      - name: Run short tests
+        env:
+          GOCACHEPROG: "gobuildcache --backend=gcs --gcs-bucket=${{ secrets.GCS_BUCKET }} --gcs-prefix=go-build-cache/${{ github.repository }}"
+        run: go test ./...

examples/github_actions_s3.yml

@@ -24,13 +24,10 @@ jobs:
         run: go install github.com/richardartoul/gobuildcache@latest
       - name: Run short tests
         env:
-          GOBUILDCACHE_BACKEND_TYPE: s3
-          GOBUILDCACHE_S3_BUCKET: EXAMPLE_BUCKET
-          GOBUILDCACHE_S3_PREFIX: EXAMPLE_PREFIX
           AWS_REGION: EXAMPLE_REGION
           AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
-          GOCACHEPROG: gobuildcache
+          GOCACHEPROG: "gobuildcache --backend=s3 --s3-bucket=EXAMPLE_BUCKET --s3-prefix=EXAMPLE_PREFIX"
         run: go test ./...
 
 

examples/github_actions_tigris.yml

@@ -24,13 +24,10 @@ jobs:
         run: go install github.com/richardartoul/gobuildcache@latest
       - name: Run short tests
         env:
-          GOBUILDCACHE_BACKEND_TYPE: s3
-          GOBUILDCACHE_S3_BUCKET: EXAMPLE_BUCKET
-          GOBUILDCACHE_S3_PREFIX: EXAMPLE_PREFIX
+          AWS_ENDPOINT_URL_S3: https://t3.storage.dev
+          AWS_ENDPOINT_URL_IAM: https://iam.storage.dev
           AWS_REGION: auto
           AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
-          AWS_ENDPOINT_URL_S3: https://t3.storage.dev
-          AWS_ENDPOINT_URL_IAM: https://iam.storage.dev
-          GOCACHEPROG: gobuildcache
+          GOCACHEPROG: "gobuildcache --backend=s3 --s3-bucket=EXAMPLE_BUCKET --s3-prefix=EXAMPLE_PREFIX"
         run: go test ./...

pkg/backends/gcs.go

@@ -28,9 +28,10 @@ type GCS struct {
 func NewGCS(bucket, prefix string) (*GCS, error) {
 	ctx := context.Background()
 
-	// Create GCS client using Application Default Credentials
-	// This will use GOOGLE_APPLICATION_CREDENTIALS env var or metadata service
-	client, err := storage.NewClient(ctx)
+	// Create GCS client using Application Default Credentials.
+	// WithJSONReads forces the JSON API for downloads (default is XML).
+	// This is required for GCS Anywhere Cache compatibility.
+	client, err := storage.NewClient(ctx, storage.WithJSONReads())
 	if err != nil {
 		return nil, fmt.Errorf("failed to create GCS client: %w", err)
 	}