$ show Songmu/ecschedule
ecschedule is a production-grade CLI tool for managing AWS EventBridge scheduled tasks that trigger ECS tasks. Written in Go, it uses declarative YAML/JSON/Jsonnet configuration files with template functions for environment variables, tfstate lookups, and SSM parameters. The tool supports full lifecycle management: dumping existing rules, diffing local vs remote state, applying changes (create/update/delete), and manually triggering rules. It provides parallel execution for performance, unified diff output with color control, and a plugin system for tfstate and ssm integrations. The codebase demonstrates strong engineering practices: clean separation of concerns, comprehensive unit tests, CI/CD pipelines, and dependency management with dependabot. The architecture is a single-binary CLI with subcommands, leveraging AWS SDK v2 and a custom template engine that defers variable resolution for idempotent diffing. Notable design patterns include a generic parallel job executor with panic recovery and context cancellation, a 'localYAMLForDiff' normalization technique to avoid flapping diffs, and a Resource Groups search-based orphan rule detection using custom tags.
The LLM identified 4 files worth highlighting for reuse:
Implements Go text/template functions (env, must_env, tfstate, tfstatef, ssm, plugin) for config file substitution. Uses a clever two-pass approach: placeholder markers (e.g., 'ecschedule::<KEY>') are injected during first template pass, then later recovered/replaced by plugin-specific regex substitutions in go-config. This enables deferred resolution of external references (env vars, tfstate lookups) while maintaining idempotent diffing. The plugin function dynamically constructs function names with prefixes, supporting multiple tfstate instances. This pattern is reusable for any Go project needing config template systems with late-bound external data.
Provides a Jsonnet VM factory (newJsonnetVM) that registers two native functions (must_env, env) mirroring the Go template helpers. This is required because Jsonnet evaluates before Go template substitution, so non-string fields (e.g., boolean `disabled`) can be set conditionally based on environment variables. The implementation is clean, well-tested, and can be extracted to add environment-aware native functions to any Go+Jsonnet project.
A generic parallel job executor using golang.org/x/sync/errgroup with a semaphore (SetLimit) for controlling concurrency. It handles panics per goroutine (logs stack trace and reports error count), respects context cancellation for graceful shutdown, and streams results via a buffered channel with a separate error channel. This is a reusable building block for any Go application needing bounded parallel execution with fault isolation and cancellation.
The localYAMLForDiff method normalizes the rule YAML by stripping BaseConfig and filling empty Role with defaultRole, ensuring symmetric diff output regardless of implicit/explicit defaults. The formatDiff function supports two output modes: colored pretty-print (using sergi/go-diff) and unified diff (using gotextdiff) with optional color control via NO_COLOR env and --no-color flag. The color control logic is centralized and follows the NO_COLOR standard. This pattern is reusable for any Go CLI that needs idempotent diff comparisons and user-configurable output formatting.