Shell Scripting

#!/usr/bin/env bash
set -euo pipefail   # exit on error, unset vars, pipe failures
 
echo "Deploying application..."

APP_NAME="my-app"
VERSION="1.0.0"
TIMESTAMP=$(date +%Y%m%d-%H%M%S)   # command substitution
 
echo "Deploying $APP_NAME v$VERSION at $TIMESTAMP"

if [ -f "./dist/app.js" ]; then
  echo "Build output found"
else
  echo "ERROR: build failed" >&2
  exit 1
fi
 
# One-liner
[ -d "/opt/app" ] || mkdir -p /opt/app

# Iterate over files
for file in ./config/*.yml; do
  echo "Validating $file"
  yamllint "$file"
done
 
# While loop
RETRIES=0
while ! curl -sf http://localhost:3000/health; do
  RETRIES=$((RETRIES + 1))
  [ $RETRIES -ge 5 ] && { echo "Service failed to start"; exit 1; }
  sleep 2
done

log() {
  echo "[$(date +%T)] $*"
}
 
wait_for_service() {
  local url="$1"
  local max_attempts="${2:-10}"
  local attempt=0
 
  until curl -sf "$url" > /dev/null; do
    attempt=$((attempt + 1))
    [ $attempt -ge $max_attempts ] && return 1
    log "Waiting for $url (attempt $attempt)..."
    sleep 3
  done
  log "$url is up"
}
 
wait_for_service "http://localhost:8080/health"

#!/usr/bin/env bash
set -euo pipefail
 
APP="my-app"
DEPLOY_DIR="/opt/$APP"
ARTIFACT="${1:?Usage: deploy.sh <artifact.tar.gz>}"
 
log() { echo "[$(date +%T)] $*"; }
 
log "Starting deployment of $ARTIFACT"
tar -xzf "$ARTIFACT" -C "$DEPLOY_DIR"
systemctl restart "$APP"
log "Deployment complete"