Kill switches — `get_killswitch`

A kill switch is an admin resource that ships in the flags blob alongside gates and configs. get_killswitch reads it and returns a boolean. No telemetry is emitted for a kill-switch read. After configure(), read it through the bound shipeasy.Client(user).

# construct once per callsite (cheap; binds the user)
client = shipeasy.Client(current_user)

if client.get_killswitch("payments_circuit_breaker"):
    # the kill switch is engaged — short-circuit the risky path
    return fallback()

Named switches

Besides its single top-level on/off value, a kill switch can carry named per-key switches — independently-flippable booleans, each under a key you choose (one per payment provider, region, vendor, …). These are configured on the kill switch itself (in the dashboard "switches" feature, or in an offline snapshot — see below); the SDK only reads them. They do not exist until you add them.

Pass that key as the second argument, switch_key, to check one named switch instead of the top-level value. The natural pattern is to pass the thing you're about to do as the key, and let the kill switch decide:

provider = "stripe"   # the variable you check against the configured switches

# construct once per callsite (cheap; binds the user)
client = shipeasy.Client(current_user)

if client.get_killswitch("payments_circuit_breaker", provider):
    # the "stripe" switch is engaged → skip Stripe, take the fallback
    return use_backup_processor()

Resolution order for get_killswitch(name, switch_key):

1. If the kill switch has a named switch matching switch_key, that switch's boolean is returned.
2. Otherwise — the key isn't configured on the kill switch — it falls back to the top-level value. So an unknown/unconfigured key behaves exactly like get_killswitch(name) with no key.

That fallback lets you wire the key everywhere first and turn individual switches on later: until you actually add the "stripe" switch, every get_killswitch("payments_circuit_breaker", "stripe") just reflects the kill switch's overall state.

Configuring switches for a test

In production these are set in the dashboard. To exercise them in a test, put a switches map on the kill switch in an offline snapshot:

shipeasy.configure_for_offline(snapshot={
    "flags": {
        "gates": {}, "configs": {},
        "killswitches": {
            "payments_circuit_breaker": {
                "value": False,                       # top-level (fallback)
                "switches": {"stripe": True, "paypal": False},
            }
        },
    },
    "experiments": {},
})

c = shipeasy.Client({"user_id": "u_1"})
assert c.get_killswitch("payments_circuit_breaker") is False           # top-level
assert c.get_killswitch("payments_circuit_breaker", "stripe") is True  # named switch
assert c.get_killswitch("payments_circuit_breaker", "paypal") is False
assert c.get_killswitch("payments_circuit_breaker", "other") is False  # falls back

Kill switches are also folded into normal gate evaluation; get_killswitch is the explicit read of that same state.