Clase 07 — JSON y APIs REST

Las APIs REST usan JSON como formato principal de comunicación. Desde la terminal usamos curl + jq para interactuar con ellas.

curl + jq — Peticiones HTTP

# GET — Obtener datos
curl -s https://pokeapi.co/api/v2/pokemon/pikachu | jq '{
  nombre: .name, id: .id,
  tipos: [.types[].type.name],
  peso: .weight, altura: .height
}'

# POST — Enviar datos
curl -s -X POST https://httpbin.org/post \
  -H "Content-Type: application/json" \
  -d '{"nombre": "RoxsRoss", "rol": "DevOps Engineer"}' | jq '.json'

# PUT — Actualizar datos
curl -s -X PUT https://httpbin.org/put \
  -H "Content-Type: application/json" \
  -d '{"id": 1, "nombre": "Ana García", "rol": "Senior Dev"}' | jq '.json'

# DELETE — Eliminar datos
curl -s -X DELETE https://httpbin.org/delete | jq '.headers'

# Ver status code
curl -s -o /dev/null -w "%{http_code}" https://pokeapi.co/api/v2/pokemon/pikachu

Ejemplo: Pokédex CLI

#!/bin/bash
POKEMON="${1:-pikachu}"
BASE_URL="https://pokeapi.co/api/v2/pokemon"

response=$(curl -s -w "\n%{http_code}" "$BASE_URL/$POKEMON")
http_code=$(echo "$response" | tail -1)
body=$(echo "$response" | sed '$d')

if [[ "$http_code" != "200" ]]; then
    echo "Error: Pokémon '$POKEMON' no encontrado (HTTP $http_code)"
    exit 1
fi

echo "$body" | jq -r '
"========================================",
"  POKÉDEX #\(.id): \(.name | ascii_upcase)",
"========================================",
"Tipos    : \([.types[].type.name] | join(", "))",
"Peso     : \(.weight / 10) kg",
"HP       : \(.stats[] | select(.stat.name == "hp") | .base_stat)",
"Ataque   : \(.stats[] | select(.stat.name == "attack") | .base_stat)",
"Velocidad: \(.stats[] | select(.stat.name == "speed") | .base_stat)",
"========================================"'

Ejemplo: GitHub API

# Info de un repositorio
curl -s https://api.github.com/repos/roxsross/devops | jq '{
  nombre: .full_name, estrellas: .stargazers_count, lenguaje: .language
}'

# Listar issues abiertos
curl -s "https://api.github.com/repos/kubernetes/kubernetes/issues?state=open&per_page=5" | \
  jq '.[] | {numero: .number, titulo: .title, autor: .user.login}'

# Con autenticación (más rate limit)
curl -s -H "Authorization: token $GITHUB_TOKEN" \
  https://api.github.com/user | jq '{login, name, public_repos}'

# Crear un issue
curl -s -X POST \
  -H "Authorization: token $GITHUB_TOKEN" \
  -H "Content-Type: application/json" \
  "https://api.github.com/repos/OWNER/REPO/issues" \
  -d '{"title":"Bug via API","body":"Descripción","labels":["bug"]}' | jq '{number, html_url}'

Script de health check

#!/bin/bash
SERVICIOS='[
  {"nombre": "API", "url": "https://httpbin.org/status/200"},
  {"nombre": "Auth", "url": "https://httpbin.org/status/200"},
  {"nombre": "DB Health", "url": "https://httpbin.org/status/503"}
]'

echo "  HEALTH CHECK - $(date '+%Y-%m-%d %H:%M')"
echo "======================================"

echo "$SERVICIOS" | jq -c '.[]' | while read -r servicio; do
    nombre=$(echo "$servicio" | jq -r '.nombre')
    url=$(echo "$servicio" | jq -r '.url')
    http_code=$(curl -s -o /dev/null -w "%{http_code}" --max-time 5 "$url")

    if [[ "$http_code" -ge 200 && "$http_code" -lt 300 ]]; then
        printf "  ✅ %-15s → OK (HTTP %s)\n" "$nombre" "$http_code"
    else
        printf "  ❌ %-15s → FAIL (HTTP %s)\n" "$nombre" "$http_code"
    fi
done

Webhook de Slack/Discord

# Enviar mensaje a Slack
enviar_slack() {
    local mensaje="$1" color="${2:-#36a64f}"
    curl -s -X POST "$SLACK_WEBHOOK" \
      -H "Content-Type: application/json" \
      -d "$(jq -n --arg text "$mensaje" --arg color "$color" \
        '{attachments: [{color: $color, text: $text, footer: "DevOps Bot"}]}')"
}

enviar_slack "Deploy exitoso en producción v2.1.0" "#36a64f"
enviar_slack "ERROR: Pipeline falló en stage test" "#dc3545"

Wrapper de API con manejo de errores

api_request() {
    local method="$1" endpoint="$2" data="$3"
    local headers=(-H "Content-Type: application/json" -H "Accept: application/json")
    [[ -n "$TOKEN" ]] && headers+=(-H "Authorization: Bearer $TOKEN")

    local response=$(curl -s -w "\n%{http_code}" -X "$method" \
      "${headers[@]}" ${data:+-d "$data"} "${BASE_URL}${endpoint}")
    local http_code=$(echo "$response" | tail -1)
    local body=$(echo "$response" | sed '$d')

    if [[ "$http_code" -ge 200 && "$http_code" -lt 300 ]]; then
        echo "$body" | jq '.'; return 0
    else
        echo "Error HTTP $http_code:" >&2
        echo "$body" | jq '.' 2>/dev/null || echo "$body" >&2; return 1
    fi
}

Paginación

#!/bin/bash
pagina=1
while true; do
    response=$(curl -s "https://pokeapi.co/api/v2/pokemon?offset=$(( (pagina-1) * 20 ))&limit=20")
    echo "Página $pagina:"
    echo "$response" | jq -r '.results[].name'
    siguiente=$(echo "$response" | jq -r '.next')
    [[ "$siguiente" == "null" ]] && break
    ((pagina++))
    [[ $pagina -gt 3 ]] && break
done