feature: add action to trigger gcp workflows

actions/gcp-workflows/CHANGELOG.md

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+# Changelog
+
+All notable changes to the GCP Workflows action will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Future enhancements will be documented here
+
+### Changed
+- Future changes will be documented here
+
+### Fixed
+- Future bug fixes will be documented here
+
+## [1.0.0] - 2025-10-05
+
+### Added
+- Initial release of GCP Workflows action
+- Support for static workflow names via `WORKFLOW_NAME` environment variable
+- Support for dynamic workflow names via `WORKFLOW_NAME_FIELD` with alert field extraction
+- Comprehensive alert data passed to workflows as JSON input
+- Support for GCP service account authentication via `GOOGLE_APPLICATION_CREDENTIALS`
+- Support for GCP Workload Identity authentication for keyless GKE integration
+- Configurable execution timeout via `TIMEOUT_SECONDS`
+- Optional workflow completion monitoring via `WAIT_FOR_COMPLETION`
+- Workflow name sanitization to ensure GCP naming compliance
+- Rich error handling and structured logging
+- Security hardening with non-root user execution (UID 1001)
+- Comprehensive test suite with unit tests and integration tests
+- Complete documentation with usage examples and Workload Identity setup
+- Example AlertReaction configurations for various use cases
+- GCP setup script (`setup-gcp.sh`) for automated resource provisioning
+- Support for extracting workflow names from alert labels and annotations using dot notation
+- Environment variable fallbacks for alert data when JSON parsing fails
+- Configurable workflow execution source identification
+- Container image optimization with multi-stage builds
+- Alpine-based runtime image for minimal attack surface

actions/gcp-workflows/Dockerfile

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+# Build stage
+FROM golang:1.24-alpine AS builder
+
+LABEL org.opencontainers.image.title="Alert Reaction: GCP Workflows Executor"
+LABEL org.opencontainers.image.description="Executes Google Cloud Workflows based on Prometheus alerts"
+LABEL org.opencontainers.image.source="https://github.com/dudizimber/alert-reactions"
+LABEL org.opencontainers.image.vendor="dudizimber"
+
+WORKDIR /app
+
+# Install git (needed for Go modules)
+RUN apk add --no-cache git
+
+# Copy go mod files
+COPY src/go.mod src/go.sum* ./
+
+# Download dependencies
+RUN go mod download
+
+# Copy source code
+COPY src/ .
+
+# Build the application
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
+    -ldflags='-w -s -extldflags "-static"' \
+    -o gcp-workflows .
+
+# Runtime stage
+FROM alpine:3.18
+
+# Install ca-certificates for HTTPS requests
+RUN apk --no-cache add ca-certificates tzdata
+
+# Create non-root user
+RUN addgroup -g 1001 -S appgroup && \
+    adduser -u 1001 -S appuser -G appgroup
+
+WORKDIR /app
+
+# Copy binary from builder stage
+COPY --from=builder /app/gcp-workflows .
+
+# Change ownership to non-root user
+RUN chown -R appuser:appgroup /app
+
+# Switch to non-root user
+USER appuser
+
+# Set timezone
+ENV TZ=UTC
+
+ENTRYPOINT ["./gcp-workflows"]