Skip to content

README.md

Latest commit

 

History

History
111 lines (88 loc) · 4.04 KB

README.md

File metadata and controls

111 lines (88 loc) · 4.04 KB
Raw

Lambda: presigned S3 downloads (coeqwalPresignDownload)

The download API for https://api.coeqwal.org. Lists available scenarios in S3 and presigns a short-lived GET so the website can serve direct downloads of the scenario ZIP and CSV outputs.

AWS resource Value
Function name coeqwalPresignDownload
Runtime Node.js 20.x or 22.x (uses built-in AWS SDK v3, no node_modules needed)
Trigger API Gateway v2 (HTTP API, id x66ckhp067), routes GET /scenario and GET /download
Action List scenario prefixes under coeqwal-model-run/scenario/, presign a GET for the requested file
Source index.mjs (single file)
Test events tests/

What it does

Route Behavior
GET /scenario Walks s3://coeqwal-model-run/scenario/<id>/ prefixes. Returns one row per scenario with the keys for the run ZIP, the CalSim output CSV, and the SV input CSV (each null if not present)
GET /download?scenario=s0020&type=zip|output|sv Validates the scenario id and type, finds the matching key in S3, presigns a GET (15 min expiry) with Content-Disposition: attachment, and returns a 302 redirect to the presigned URL

Both routes set permissive CORS so the frontend can call them from any origin.

Deploy updates

Single index.mjs, no external deps. Same flow as the ETL trigger.

Via AWS Console:

  1. AWS Console -> Lambda -> Functions -> coeqwalPresignDownload
  2. Click the Code tab
  3. Select all in the inline editor, paste the full contents of index.mjs
  4. Click Deploy

Via Cloud9 / CLI:

cd ~/environment/coeqwal-backend/api/lambda/coeqwalPresignDownload
zip lambda.zip index.mjs
aws lambda update-function-code --function-name coeqwalPresignDownload --zip-file fileb://lambda.zip
rm lambda.zip

Test events

File Route exercised
tests/test-event-scenario-list.json GET /scenario. Lists all available scenarios
tests/test-event-download.json GET /download?scenario=s0020&type=zip. Returns a presigned URL

In the AWS Console: Lambda -> coeqwalPresignDownload -> Test tab. Create a new test event and paste the JSON from one of the files in tests/.

Via AWS CLI:

# List scenarios
aws lambda invoke \
  --function-name coeqwalPresignDownload \
  --cli-binary-format raw-in-base64-out \
  --payload file://api/lambda/coeqwalPresignDownload/tests/test-event-scenario-list.json \
  --log-type Tail \
  response.json \
  --query 'LogResult' --output text | base64 -d
cat response.json | jq .

# Download presign
aws lambda invoke \
  --function-name coeqwalPresignDownload \
  --cli-binary-format raw-in-base64-out \
  --payload file://api/lambda/coeqwalPresignDownload/tests/test-event-download.json \
  --log-type Tail \
  response.json \
  --query 'LogResult' --output text | base64 -d

Lambda configuration checklist

  • Runtime: Node.js 20.x or 22.x
  • Handler: index.handler
  • Timeout: 30 seconds
  • Memory: 256 MB minimum
  • Environment variable (optional): COEQWAL_S3_BUCKET - defaults to coeqwal-model-run if unset
  • IAM role has S3 read access to coeqwal-model-run bucket

Common issues

S3 permission error

AccessDenied: Access Denied

Add S3 read to the Lambda's IAM role:

{
  "Effect": "Allow",
  "Action": ["s3:ListBucket", "s3:GetObject"],
  "Resource": [
    "arn:aws:s3:::coeqwal-model-run",
    "arn:aws:s3:::coeqwal-model-run/*"
  ]
}

Path not found (404)

{"error": "Not Found"}

Check the API Gateway route matches the Lambda's expected paths (/scenario, /download).

Related

  • The FastAPI service that serves the rest of the API: ../../coeqwal-api/
  • Frontend caller (separate repo, coeqwal-website): apps/main/app/lib/api/fileDownloadApi.ts
  • AWS-side resource details (API Gateway id, IAM, costs): INFRASTRUCTURE.md in the private coeqwal-private-docs repo