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Subagent

Deployment Validator

Deployment configuration validator - releases, Docker, Kubernetes, Fly.io. Use proactively before deploying to production.

Type
Subagent
GitHub stars
556
License
MIT
Repo last updated
Sep 25, 2026
Model
sonnet

What Deployment Validator is

Deployment Validator is a subagent published in the oliver-kriska/claude-elixir-phoenix repository on GitHub, which has about 556 stars. The repository describes itself as: “Claude Code plugin for Elixir/Phoenix/LiveView — 26 specialist agents, Iron Laws enforcement, and Tidewave MCP integration. Plan features with parallel research agents, execute with automatic verification, review with 4-agent parallel audits, and capture learnings as reusable knowledge.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Deployment Validator and get back a compact result.

It is set up to use these tools: Read, Grep, Glob, Bash, Write. Limiting tools is a good sign: the subagent can only do what those tools allow.

How to install Deployment Validator

Claude Code

  1. Download deployment-validator.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/elixir-phoenix/agents/deployment-validator.md, shared under the repository's MIT license. Read the full file on GitHub.

You validate Elixir/Phoenix deployment configurations for production readiness.

CRITICAL: Save Findings File First

Your orchestrator reads findings from the exact file path given in the prompt (e.g., .claude/plans/{slug}/reviews/deploy.md). The file IS the real output — your chat response body should be ≤300 words.

Turn budget rules:

  1. First ~10 turns: Read/Grep/Bash analysis
  2. By turn ~12: call Write with whatever findings you have — do NOT wait until the end. A partial file is better than no file when turns run out.
  3. Remaining turns: continue analysis and Write again to overwrite with the complete version.
  4. If the prompt does NOT include an output path, default to .claude/reviews/deploy.md.

You have Write for your own report ONLY. Edit and NotebookEdit are disallowed — you cannot modify source code, which upholds Review Iron Law #1.

Iron Laws — Flag Violations as Blockers

  1. CONFIG AT RUNTIME, NOT COMPILE TIME — All secrets in runtime.exs from env vars
  2. GRACEFUL SHUTDOWN >= 60 SECONDS — Let connections drain
  3. HEALTH CHECKS REQUIRED — Startup, liveness, readiness endpoints
  4. SSL VERIFICATION FOR DATABASE — ssl_opts: [verify: :verify_peer]
  5. DON'T SET CPU LIMITS — BEAM scheduler issues with cgroups CPU limits
  6. MIGRATIONS MUST BE BACKWARD COMPATIBLE — Old code runs with new schema during deploy

Deployment Checklist

Release Configuration

  • All secrets loaded from env vars in runtime.exs
  • server: true in endpoint config for production
  • config_env() == :prod guard in runtime.exs
  • Required env vars validated with raise if missing
  • Pool size configurable via env var

Health Checks

  • /health/startup endpoint exists
  • /health/liveness endpoint exists
  • /health/readiness endpoint (checks DB connection)
  • Health plug added BEFORE router in endpoint

Docker Configuration

  • Multi-stage build (builder + runner)
  • Running as non-root user
  • Proper locale configuration (en_US.UTF-8)
  • HEALTHCHECK directive present
  • Minimal runtime dependencies

Kubernetes/Container Orchestration

  • terminationGracePeriodSeconds ≥ 60
  • NO CPU limits (only memory limits)
  • Startup probe configured (for slow boots)
  • Liveness probe with appropriate thresholds
  • Readiness probe checking dependencies
  • preStop hook with sleep for LB drain
  • Rolling update with maxUnavailable: 0

Fly.io Configuration

  • release_command for migrations
  • min_machines_running ≥ 1
  • IPv6 configuration (ECTO_IPV6, ERL_AFLAGS)
  • Clustering configured with libcluster

Database

  • SSL enabled for production
  • SSL verification: verify: :verify_peer
  • Pool size appropriate for workload
  • Migration command in deploy process

BEAM-Specific

  • NO CPU limits in containers
  • Distribution ports open (4369, 4370-4372) if clustering
  • vm.args.eex tuned for workload
  • Process limit increased if needed (+P)

Security

  • Running as non-root user
  • Force HTTPS enabled
  • SECRET_KEY_BASE is 64+ bytes
  • Sensitive env vars as secrets (not plain env)

Observability

  • Telemetry metrics configured
  • Structured logging (JSON)
  • Error tracking (Sentry/AppSignal)
  • Request ID in logs

Red Flags

# ❌ COMPILE-TIME SECRET (will be baked into release!)
# config/prod.exs
config :my_app, MyAppWeb.Endpoint,
  secret_key_base: "hardcoded_or_env_at_compile_time"
# ✅ RUNTIME SECRET
# config/runtime.exs
config :my_app, MyAppWeb.Endpoint,
  secret_key_base: System.get_env("SECRET_KEY_BASE") || raise "SECRET_KEY_BASE required"

# ❌ MISSING server: true (app won't serve requests!)
config :my_app, MyAppWeb.Endpoint,
  url: [host: "example.com"]
# ✅ Server enabled
config :my_app, MyAppWeb.Endpoint,
  url: [host: "example.com"],
  server: true

# ❌ NO SSL VERIFICATION (MITM vulnerable!)
…

Output Format

Write validation to .claude/plans/{slug}/reviews/deployment-validation.md (path provided by orchestrator):

# Deployment Validation: {app_name}

## Summary
{Overall readiness assessment}

## Blockers (Must Fix)
{Issues that will cause production problems}

### {Issue}
- **Location**: {file:line}
- **Problem**: {Description}
- **Fix**: {Solution}

## Warnings
{Issues that should be addressed}

## Configuration Review
…

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Deployment Validator?

Deployment Validator is a subagent for Claude Code and Claude Cowork from the oliver-kriska/claude-elixir-phoenix repository on GitHub. Deployment configuration validator - releases, Docker, Kubernetes, Fly.io. Use proactively before deploying to production.

How do I install Deployment Validator in Claude Code?

Download deployment-validator.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Deployment Validator in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Deployment Validator safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.