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feat: Add EC2 region detection and cost optimization features

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Simone Scarduzio
2025-10-12 22:41:48 +02:00
parent 4f56c4b600
commit b2ca59490b
8 changed files with 504 additions and 8 deletions
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12
CHANGELOG.md
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@@ -8,6 +8,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
## [Unreleased]
### Added
- **EC2 Region Detection & Cost Optimization**
- Automatic detection of EC2 instance region using IMDSv2
- Warns when EC2 region ≠ S3 client region (potential cross-region charges)
- Different warnings for auto-detected vs. explicit `--region` flag mismatches
- Green checkmark when regions are aligned (optimal configuration)
- Can be disabled with `DG_DISABLE_EC2_DETECTION=true` environment variable
- Helps users optimize for cost and performance before migration starts
- **New CLI Command**: `deltaglider migrate` for S3-to-S3 bucket migration with compression
- Supports resume capability (skips already migrated files)
- Real-time progress tracking with file count and statistics
@@ -16,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- Dry run mode with `--dry-run` flag
- Include/exclude pattern filtering
- Shows compression statistics after migration
- **EC2-aware region logging**: Detects EC2 instance and warns about cross-region charges
- **FIXED**: Now correctly preserves original filenames during migration
- **S3-to-S3 Recursive Copy**: `deltaglider cp -r s3://source/ s3://dest/` now supported
- Automatically uses migration functionality with prefix preservation
@@ -32,6 +40,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
- Previously created files with temp names like `tmp1b9cpdsn.zip`
- Now correctly uses original filenames from source S3 keys
- Fixed by adding `override_name` parameter to `DeltaService.put()`
- **CLI Region Support**: `--region` flag now properly passes region to boto3 client
- Previously only set environment variable, relied on boto3 auto-detection
- Now explicitly passes `region_name` to `boto3.client()` via `boto3_kwargs`
- Ensures consistent behavior with `DeltaGliderClient` SDK
### Changed
- Recursive S3-to-S3 copy operations now preserve source prefix structure by default

6
README.md
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@@ -558,6 +558,12 @@ deltaglider migrate --exclude "*.log" s3://old/ s3://new/
- **Resume Support**: Migration automatically skips files that already exist in the destination
- **Progress Tracking**: Shows real-time migration progress and statistics
- **Safety First**: Interactive confirmation shows file count before starting
- **EC2 Cost Optimization**: Automatically detects EC2 instance region and warns about cross-region charges
- ✅ Green checkmark when regions align (no extra charges)
- ℹ️ INFO when auto-detected mismatch (suggests optimal region)
- ⚠️ WARNING when user explicitly set wrong `--region` (expect data transfer costs)
- Disable with `DG_DISABLE_EC2_DETECTION=true` if needed
- **AWS Region Transparency**: Displays the actual AWS region being used
- **Prefix Preservation**: By default, source prefix is preserved in destination (use `--no-preserve-prefix` to disable)
- **S3-to-S3 Transfer**: Both regular S3 and DeltaGlider buckets supported

242
docs/EC2_REGION_DETECTION.md Normal file
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@@ -0,0 +1,242 @@
# EC2 Region Detection & Cost Optimization
DeltaGlider automatically detects when you're running on an EC2 instance and warns you about potential cross-region data transfer charges.
## Overview
When running `deltaglider migrate` on an EC2 instance, DeltaGlider:
1. **Detects EC2 Environment**: Uses IMDSv2 (Instance Metadata Service v2) to determine if running on EC2
2. **Retrieves Instance Region**: Gets the actual AWS region where your EC2 instance is running
3. **Compares Regions**: Checks if your EC2 region matches the S3 client region
4. **Warns About Costs**: Displays clear warnings when regions don't match
## Why This Matters
**AWS Cross-Region Data Transfer Costs**:
- **Same region**: No additional charges for data transfer
- **Cross-region**: $0.02 per GB transferred (can add up quickly for large migrations)
- **NAT Gateway**: Additional charges if going through NAT
**Example Cost Impact**:
- Migrating 1TB from `us-east-1` EC2 → `us-west-2` S3 = ~$20 in data transfer charges
- Same migration within same region = $0 in data transfer charges
## Output Examples
### Scenario 1: Regions Aligned (Optimal) ✅
```bash
$ deltaglider migrate s3://old-bucket/ s3://new-bucket/
EC2 Instance: us-east-1a
S3 Client Region: us-east-1
✓ Regions aligned - no cross-region charges
Migrating from s3://old-bucket/
to s3://new-bucket/
...
```
**Result**: No warnings, optimal configuration, no extra charges.
---
### Scenario 2: Auto-Detected Mismatch (INFO) ℹ️
```bash
$ deltaglider migrate s3://old-bucket/ s3://new-bucket/
EC2 Instance: us-west-2a
S3 Client Region: us-east-1
ℹ️ INFO: EC2 region (us-west-2) differs from configured S3 region (us-east-1)
Consider using --region us-west-2 to avoid cross-region charges.
Migrating from s3://old-bucket/
to s3://new-bucket/
...
```
**Result**: Informational warning, suggests optimal region. User didn't explicitly set wrong region, so it's likely from their AWS config.
---
### Scenario 3: Explicit Region Override Mismatch (WARNING) ⚠️
```bash
$ deltaglider migrate --region us-east-1 s3://old-bucket/ s3://new-bucket/
EC2 Instance: us-west-2a
S3 Client Region: us-east-1
⚠️ WARNING: EC2 region=us-west-2 != S3 client region=us-east-1
Expect cross-region/NAT data charges. Align regions (set client region=us-west-2)
before proceeding. Or drop --region for automatic region resolution.
Migrating from s3://old-bucket/
to s3://new-bucket/
...
```
**Result**: Strong warning because user explicitly set the wrong region with `--region` flag. They might not realize the cost implications.
---
### Scenario 4: Not on EC2
```bash
$ deltaglider migrate s3://old-bucket/ s3://new-bucket/
S3 Client Region: us-east-1
Migrating from s3://old-bucket/
to s3://new-bucket/
...
```
**Result**: Simple region display, no EC2 warnings (not applicable).
## Configuration
### Disable EC2 Detection
If you want to disable EC2 detection (e.g., for testing or if it causes issues):
```bash
export DG_DISABLE_EC2_DETECTION=true
deltaglider migrate s3://old/ s3://new/
```
Or in your script:
```python
import os
os.environ["DG_DISABLE_EC2_DETECTION"] = "true"
```
### How It Works
DeltaGlider uses **IMDSv2** (Instance Metadata Service v2) for security:
1. **Token Request** (PUT with TTL):
```
PUT http://169.254.169.254/latest/api/token
X-aws-ec2-metadata-token-ttl-seconds: 21600
```
2. **Metadata Request** (GET with token):
```
GET http://169.254.169.254/latest/meta-data/placement/region
X-aws-ec2-metadata-token: <token>
```
3. **Fast Timeout**: 1 second timeout for non-EC2 environments (no delay if not on EC2)
### Security Notes
- **IMDSv2 Only**: DeltaGlider uses the more secure IMDSv2, not the legacy IMDSv1
- **No Credentials**: Only reads metadata, never accesses credentials
- **Graceful Fallback**: Silently skips detection if IMDS unavailable
- **No Network Impact**: Uses local-only IP (169.254.169.254), never leaves the instance
## Best Practices
### For Cost Optimization
1. **Same Region**: Always try to keep EC2 instance and S3 bucket in the same region
2. **Check First**: Run with `--dry-run` to verify the setup before actual migration
3. **Use Auto-Detection**: Don't specify `--region` unless you have a specific reason
4. **Monitor Costs**: Use AWS Cost Explorer to track cross-region data transfer
### For Terraform/IaC
```hcl
# Good: EC2 and S3 in same region
resource "aws_instance" "app" {
region = "us-west-2"
}
resource "aws_s3_bucket" "data" {
region = "us-west-2" # Same region
}
```
### For Multi-Region Setups
If you MUST do cross-region transfers:
1. **Use VPC Endpoints**: Reduce NAT Gateway costs
2. **Schedule Off-Peak**: AWS charges less during off-peak hours in some regions
3. **Consider S3 Transfer Acceleration**: May be cheaper for very large transfers
4. **Batch Operations**: Minimize number of API calls
## Technical Details
### EC2MetadataAdapter
Location: `src/deltaglider/adapters/ec2_metadata.py`
Key methods:
- `is_running_on_ec2()`: Detects EC2 environment
- `get_region()`: Returns AWS region code (e.g., "us-east-1")
- `get_availability_zone()`: Returns AZ (e.g., "us-east-1a")
### Region Logging
Location: `src/deltaglider/app/cli/aws_compat.py`
Function: `log_aws_region(service, region_override=False)`
Logic:
- If not EC2: Show S3 region only
- If EC2 + regions match: Green checkmark ✅
- If EC2 + auto-detected mismatch: Blue INFO ℹ️
- If EC2 + `--region` mismatch: Yellow WARNING ⚠️
## Troubleshooting
### "Cannot connect to IMDS"
**Cause**: Network policy blocks access to 169.254.169.254
**Solution**:
```bash
# Test IMDS connectivity
TOKEN=$(curl -X PUT "http://169.254.169.254/latest/api/token" \
-H "X-aws-ec2-metadata-token-ttl-seconds: 21600")
curl -H "X-aws-ec2-metadata-token: $TOKEN" \
http://169.254.169.254/latest/meta-data/placement/region
# If it fails, disable detection
export DG_DISABLE_EC2_DETECTION=true
```
### "Wrong region detected"
**Cause**: Cached metadata or race condition
**Solution**: DeltaGlider caches metadata for performance. Restart the process to refresh.
### "Warning appears but I want cross-region"
**Cause**: You intentionally need cross-region transfer
**Solution**: This is just a warning, not an error. The migration will proceed. The warning helps you confirm you understand the cost implications.
## FAQ
**Q: Does this slow down my migrations?**
A: No. EC2 detection happens once before migration starts (< 100ms). It doesn't affect migration performance.
**Q: What if I'm not on EC2 but the detection is slow?**
A: The timeout is 1 second. If IMDS is unreachable, it fails fast. Disable with `DG_DISABLE_EC2_DETECTION=true`.
**Q: Does this work on Fargate/ECS/Lambda?**
A: Yes! All AWS compute services support IMDSv2. The detection works the same way.
**Q: Can I use this with LocalStack/MinIO?**
A: Yes. When using `--endpoint-url`, DeltaGlider skips EC2 detection (not applicable for non-AWS S3).
**Q: Will this detect VPC endpoints?**
A: No. VPC endpoints don't change the "region" from an EC2 perspective. The warning still applies if regions don't match.
## Related Documentation
- [AWS Data Transfer Pricing](https://aws.amazon.com/ec2/pricing/on-demand/#Data_Transfer)
- [AWS IMDSv2 Documentation](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/configuring-instance-metadata-service.html)
- [S3 Transfer Costs](https://aws.amazon.com/s3/pricing/)

2
pyproject.toml
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@@ -53,6 +53,7 @@ dependencies = [
"click>=8.1.0",
"cryptography>=42.0.0",
"python-dateutil>=2.9.0",
"requests>=2.32.0",
]
[project.urls]
@@ -109,6 +110,7 @@ dev-dependencies = [
"mypy>=1.13.0",
"boto3-stubs[s3]>=1.35.0",
"types-python-dateutil>=2.9.0",
"types-requests>=2.32.0",
"setuptools-scm>=8.0.0",
]

14
src/deltaglider/adapters/__init__.py
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@@ -6,20 +6,22 @@ from .cache_fs import FsCacheAdapter
from .cache_memory import MemoryCache
from .clock_utc import UtcClockAdapter
from .diff_xdelta import XdeltaAdapter
from .ec2_metadata import EC2MetadataAdapter
from .hash_sha import Sha256Adapter
from .logger_std import StdLoggerAdapter
from .metrics_noop import NoopMetricsAdapter
from .storage_s3 import S3StorageAdapter
__all__ = [
"S3StorageAdapter",
"XdeltaAdapter",
"Sha256Adapter",
"FsCacheAdapter",
"ContentAddressedCache",
"EC2MetadataAdapter",
"EncryptedCache",
"FsCacheAdapter",
"MemoryCache",
"UtcClockAdapter",
"StdLoggerAdapter",
"NoopMetricsAdapter",
"S3StorageAdapter",
"Sha256Adapter",
"StdLoggerAdapter",
"UtcClockAdapter",
"XdeltaAdapter",
]

126
src/deltaglider/adapters/ec2_metadata.py Normal file
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@@ -0,0 +1,126 @@
"""EC2 Instance Metadata Service (IMDS) adapter.
Provides access to EC2 instance metadata using IMDSv2 with token-based authentication.
Falls back gracefully when not running on EC2.
"""
import os
import requests
class EC2MetadataAdapter:
"""Adapter for EC2 Instance Metadata Service (IMDSv2)."""
IMDS_BASE_URL = "http://169.254.169.254/latest"
TOKEN_URL = f"{IMDS_BASE_URL}/api/token"
TOKEN_TTL_SECONDS = 21600 # 6 hours
TOKEN_HEADER = "X-aws-ec2-metadata-token"
TIMEOUT_SECONDS = 1 # Fast timeout for non-EC2 environments
def __init__(self) -> None:
"""Initialize EC2 metadata adapter."""
self._token: str | None = None
self._is_ec2: bool | None = None
self._region: str | None = None
def is_running_on_ec2(self) -> bool:
"""Check if running on an EC2 instance.
Returns:
True if running on EC2, False otherwise
Note:
Result is cached after first check for performance.
"""
if self._is_ec2 is not None:
return self._is_ec2
# Skip check if explicitly disabled
if os.environ.get("DG_DISABLE_EC2_DETECTION", "").lower() in ("true", "1", "yes"):
self._is_ec2 = False
return False
try:
# Try to get IMDSv2 token
self._token = self._get_token()
self._is_ec2 = self._token is not None
except Exception:
self._is_ec2 = False
return self._is_ec2
def get_region(self) -> str | None:
"""Get the EC2 instance's AWS region.
Returns:
AWS region code (e.g., "us-east-1") or None if not on EC2
Note:
Result is cached after first successful fetch.
"""
if not self.is_running_on_ec2():
return None
if self._region is not None:
return self._region
try:
if self._token:
response = requests.get(
f"{self.IMDS_BASE_URL}/meta-data/placement/region",
headers={self.TOKEN_HEADER: self._token},
timeout=self.TIMEOUT_SECONDS,
)
if response.status_code == 200:
self._region = response.text.strip()
return self._region
except Exception:
pass
return None
def get_availability_zone(self) -> str | None:
"""Get the EC2 instance's availability zone.
Returns:
Availability zone (e.g., "us-east-1a") or None if not on EC2
"""
if not self.is_running_on_ec2():
return None
try:
if self._token:
response = requests.get(
f"{self.IMDS_BASE_URL}/meta-data/placement/availability-zone",
headers={self.TOKEN_HEADER: self._token},
timeout=self.TIMEOUT_SECONDS,
)
if response.status_code == 200:
return str(response.text.strip())
except Exception:
pass
return None
def _get_token(self) -> str | None:
"""Get IMDSv2 token for authenticated metadata requests.
Returns:
IMDSv2 token or None if unable to retrieve
Note:
Uses IMDSv2 for security. IMDSv1 is not supported.
"""
try:
response = requests.put(
self.TOKEN_URL,
headers={"X-aws-ec2-metadata-token-ttl-seconds": str(self.TOKEN_TTL_SECONDS)},
timeout=self.TIMEOUT_SECONDS,
)
if response.status_code == 200:
return response.text.strip()
except Exception:
pass
return None

99
src/deltaglider/app/cli/aws_compat.py
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@@ -17,9 +17,87 @@ __all__ = [
"copy_s3_to_s3",
"migrate_s3_to_s3",
"handle_recursive",
"log_aws_region",
]
def log_aws_region(service: DeltaService, region_override: bool = False) -> None:
"""Log the AWS region being used and warn about cross-region charges.
This function:
1. Detects if running on EC2
2. Compares EC2 region with S3 client region
3. Warns about potential cross-region data transfer charges
4. Helps users optimize for cost and performance
Args:
service: DeltaService instance with storage adapter
region_override: True if user explicitly specified --region flag
"""
try:
from ...adapters.ec2_metadata import EC2MetadataAdapter
from ...adapters.storage_s3 import S3StorageAdapter
if not isinstance(service.storage, S3StorageAdapter):
return # Not using S3 storage, skip
# Get S3 client region
s3_region = service.storage.client.meta.region_name
if not s3_region:
s3_region = "us-east-1" # boto3 default
# Check if running on EC2
ec2_metadata = EC2MetadataAdapter()
if ec2_metadata.is_running_on_ec2():
ec2_region = ec2_metadata.get_region()
ec2_az = ec2_metadata.get_availability_zone()
# Log EC2 context
click.echo(f"EC2 Instance: {ec2_az or ec2_region or 'unknown'}")
click.echo(f"S3 Client Region: {s3_region}")
# Check for region mismatch
if ec2_region and ec2_region != s3_region:
if region_override:
# User explicitly set --region, warn about costs
click.echo("")
click.secho(
f"⚠️ WARNING: EC2 region={ec2_region} != S3 client region={s3_region}",
fg="yellow",
bold=True,
)
click.secho(
f" Expect cross-region/NAT data charges. Align regions (set client region={ec2_region})",
fg="yellow",
)
click.secho(
" before proceeding. Or drop --region for automatic region resolution.",
fg="yellow",
)
click.echo("")
else:
# Auto-detected mismatch, but user can still cancel
click.echo("")
click.secho(
f"ℹ️ INFO: EC2 region ({ec2_region}) differs from configured S3 region ({s3_region})",
fg="cyan",
)
click.secho(
f" Consider using --region {ec2_region} to avoid cross-region charges.",
fg="cyan",
)
click.echo("")
elif ec2_region and ec2_region == s3_region:
# Regions match - optimal configuration
click.secho("✓ Regions aligned - no cross-region charges", fg="green")
else:
# Not on EC2, just show S3 region
click.echo(f"S3 Client Region: {s3_region}")
except Exception:
pass # Silently ignore errors getting region info
def is_s3_path(path: str) -> bool:
"""Check if path is an S3 URL."""
return path.startswith("s3://")
@@ -239,6 +317,7 @@ def migrate_s3_to_s3(
dry_run: bool = False,
skip_confirm: bool = False,
preserve_prefix: bool = True,
region_override: bool = False,
) -> None:
"""Migrate objects from one S3 location to another with delta compression.
@@ -247,6 +326,21 @@ def migrate_s3_to_s3(
- Progress tracking: Shows migration progress
- Confirmation prompt: Shows file count before starting
- Prefix preservation: Optionally preserves source prefix structure in destination
- EC2 region detection: Warns about cross-region data transfer charges
Args:
service: DeltaService instance
source_url: Source S3 URL
dest_url: Destination S3 URL
exclude: Pattern to exclude files
include: Pattern to include files
quiet: Suppress output
no_delta: Disable delta compression
max_ratio: Maximum delta/file ratio
dry_run: Show what would be migrated without migrating
skip_confirm: Skip confirmation prompt
preserve_prefix: Preserve source prefix in destination
region_override: True if user explicitly specified --region flag
"""
import fnmatch
@@ -269,6 +363,10 @@ def migrate_s3_to_s3(
effective_dest_prefix = (dest_prefix or "") + source_prefix_name + "/"
if not quiet:
# Log AWS region being used (helps users verify their configuration)
# Pass region_override to warn about cross-region charges if user explicitly set --region
log_aws_region(service, region_override=region_override)
if preserve_prefix and source_prefix:
click.echo(f"Migrating from s3://{source_bucket}/{source_prefix}")
click.echo(f" to s3://{dest_bucket}/{effective_dest_prefix}")
@@ -530,4 +628,5 @@ def handle_recursive(
dry_run=False,
skip_confirm=True, # Don't prompt for cp command
preserve_prefix=True, # Always preserve prefix for cp -r
region_override=False, # cp command doesn't track region override explicitly
)

11
src/deltaglider/app/cli/main.py
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@@ -7,6 +7,7 @@ import shutil
import sys
import tempfile
from pathlib import Path
from typing import Any
import click
@@ -50,7 +51,7 @@ def create_service(
# Register cleanup handler to remove cache on exit
atexit.register(lambda: shutil.rmtree(cache_dir, ignore_errors=True))
# Set AWS environment variables if provided
# Set AWS environment variables if provided (for compatibility with other AWS tools)
if endpoint_url:
os.environ["AWS_ENDPOINT_URL"] = endpoint_url
if region:
@@ -58,9 +59,14 @@ def create_service(
if profile:
os.environ["AWS_PROFILE"] = profile
# Build boto3_kwargs for explicit parameter passing (preferred over env vars)
boto3_kwargs: dict[str, Any] = {}
if region:
boto3_kwargs["region_name"] = region
# Create adapters
hasher = Sha256Adapter()
storage = S3StorageAdapter(endpoint_url=endpoint_url)
storage = S3StorageAdapter(endpoint_url=endpoint_url, boto3_kwargs=boto3_kwargs)
diff = XdeltaAdapter()
# SECURITY: Configurable cache with encryption and backend selection
@@ -730,6 +736,7 @@ def migrate(
dry_run=dry_run,
skip_confirm=yes,
preserve_prefix=not no_preserve_prefix,
region_override=region is not None, # True if user explicitly specified --region
)
except Exception as e: