feat: add composite action for validating a bucket URI

.github/actions/validate-bucket-uri/action.yml

@@ -0,0 +1,20 @@
+name: Validate S3 Bucket URI
+description: Validates an AWS S3 bucket URI.
+inputs:
+  s3-bucket-uri:
+    type: string
+    description: "The S3 bucket URI to validate"
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Validate
+      shell: bash
+      env:
+        REGEXP: "^s3://[a-zA-Z0-9!_.*'()/-]+$"
+        S3_BUCKET_URI: ${{ inputs.s3-bucket-uri }}
+      run: |
+        if ! echo "$S3_BUCKET_URI" | grep -q -E $REGEXP; then
+          echo "error: not a valid S3 bucket URI '$S3_BUCKET_URI'" >/dev/stderr
+          exit 1
+        fi

README.md

@@ -29,6 +29,7 @@
     - [AWS deploy](#aws-deploy)
   - [Composite Actions](#composite-actions)
     - [Tagging](#tagging)
+    - [Validate bucket URI](#validate-bucket-uri)
   - [Other documentation](#other-documentation)
     - [Dependabot and Actions workflow imports](#dependabot-and-actions-workflow-imports)
     - [Versioning for container images](#versioning-for-container-images)
@@ -1229,6 +1230,25 @@ jobs:
       tag: ${{ needs.prepare.outputs.tag }}
 ```
 
+### Validate bucket URI
+
+STATUS: beta
+
+Validate an S3 bucket URI by checking it is in the right format and contains only valid characters.
+
+```yaml
+on: [push]
+
+jobs:
+  prepare:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Validate bucket
+        uses: GeoNet/Actions/.github/actions/validate-bucket-uri@main
+        with:
+          s3-bucket-uri: s3://my-bucket-to-validate/my-bucket-prefix
+```
+
 ## Other documentation
 
 ### Dependabot and Actions workflow imports