Deploy

What it does

When your agent uses it

• Configuring Fly.io
• Production migrations

Example prompts

• “/deploy”

Requirements

• Node.js
• Docker
• A credential in S3_ACCESS_KEY
• A credential in S3_SECRET_KEY

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

1. 1Config at runtime, not compile time — Secrets in config.exs get baked into the release binary. Use runtime.exs with env vars so secrets…
2. 2Graceful shutdown ≥ 60 seconds — Shorter timeouts kill in-flight requests and WebSocket connections mid-operation, causing data loss for…
3. 3Health checks required — Without startup/liveness/readiness endpoints, orchestrators can't distinguish a booting node from a dead one…
4. 4SSL verification for database — Skipping verify: :verify_peer allows MITM attacks between your app and database; production data traverses…
5. 5No CPU limits — The BEAM scheduler assumes it owns all cores; cgroups CPU limits cause scheduler collapse where the VM thinks it has more…
6. 6Guard optional service credentials — runtime.exs runs whenever a

What it can do on your machine

Read from SKILL.md and the folder at commit 9767a82. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are elixir).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names these keys or tokens, usually read from environment variables:

  • S3_ACCESS_KEY
  • S3_SECRET_KEY

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Deploy loads about 1.1k tokens when it runs, and up to ~2.3k if it reads all its reference files. Until then it costs about 48 tokens; SKILL.md has 354 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~48

When it runs · the whole SKILL.md, loaded when a task matches

~1.1k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~2.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from oliver-kriska/claude-elixir-phoenix at commit 9767a82, republished under its MIT licence (© oliver-kriska). 354 words, ~1,149 tokens.

name

deploy

description

Elixir/Phoenix deployment patterns — Dockerfile, fly.toml, runtime.exs, mix release, rel/ overlays. Use when configuring Fly.io, Docker, CI/CD, health checks, or production migrations.

if config_env() == :prod do
  database_url = System.get_env("DATABASE_URL") || raise "DATABASE_URL is required"
  secret_key_base = System.get_env("SECRET_KEY_BASE") || raise "SECRET_KEY_BASE is required"
  host = System.get_env("PHX_HOST") || raise "PHX_HOST is required"

  config :my_app, MyApp.Repo,
    url: database_url,
    pool_size: String.to_integer(System.get_env("POOL_SIZE") || "10"),
    ssl: true,
    ssl_opts: [verify: :verify_peer]

  config :my_app, MyAppWeb.Endpoint,
    url: [host: host, port: 443, scheme: "https"],
    http: [ip: {0, 0, 0, 0}, port: String.to_integer(System.get_env("PORT") || "4000")],
    secret_key_base: secret_key_base,
    server: true
end

s3_config =
  if System.get_env("STORAGE_BACKEND") == "s3" do
    [
      access_key_id:
        System.get_env("S3_ACCESS_KEY") ||
          raise("S3_ACCESS_KEY is required when STORAGE_BACKEND=s3"),
      secret_access_key:
        System.get_env("S3_SECRET_KEY") ||
          raise("S3_SECRET_KEY is required when STORAGE_BACKEND=s3")
    ]
  else
    []
  end

config :my_app, :s3_config, s3_config

def call(%{path_info: ["health", "readiness"]} = conn, _opts) do
  case Ecto.Adapters.SQL.query(MyApp.Repo, "SELECT 1", []) do
    {:ok, _} -> send_resp(conn, 200, ~s({"status":"ok"})) |> halt()
    {:error, _} -> send_resp(conn, 503, ~s({"status":"error"})) |> halt()
  end
end

© oliver-kriska, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in targets/pi/skills/deploy of oliver-kriska/claude-elixir-phoenix.

• SKILL.md
• references/docker-config.md
• references/flyio-config.md

Open the folder on GitHubat commit 9767a82