healthcheck_example.ctst

// Health checks and restart policies.
//
// Healthchecks control CONNECT ordering — a dependency is not
// considered ready until its healthcheck passes. Combined with
// restart policies, they enable self-healing deployments.

COMPONENT api {
    image    = "file:///opt/images/myapp-api"
    port     = 8080
    memory   = "256MiB"
    readonly = true
    // Restart only on crash or when healthcheck reports unhealthy.
    restart  = "on-failure"
    healthcheck = {
        command      = ["curl", "-f", "http://localhost:8080/healthz"]
        interval     = "10s"
        timeout      = "3s"
        retries      = 5
        start_period = "20s"
    }
    env = {
        DATABASE_URL = "postgres://${db.host}:${db.port}/app"
    }
}

COMPONENT db {
    image    = "file:///opt/images/postgres-16"
    port     = 5432
    memory   = "512MiB"
    volume   = "/data/healthcheck-demo:/var/lib/postgresql/data"
    readonly = false
    // Critical data store — always restart regardless of exit code.
    restart  = "always"
    healthcheck = {
        command  = ["pg_isready", "-U", "postgres"]
        interval = "5s"
        timeout  = "2s"
        retries  = 10
    }
    env = {
        POSTGRES_PASSWORD = "${secret.db_password}"
    }
}

COMPONENT cache {
    image    = "tar:///opt/images/redis-7.tar"
    port     = 6379
    memory   = "128MiB"
    readonly = true
    // Redis restarts on failure; healthcheck verifies PING response.
    restart  = "on-failure"
    healthcheck = {
        command      = ["redis-cli", "ping"]
        interval     = "5s"
        timeout      = "2s"
        retries      = 5
        start_period = "5s"
    }
    command = ["redis-server", "--maxmemory", "100mb"]
}

CONNECT api -> db
CONNECT api -> cache

EXPOSE 8080