deploy-redirect-lambda.md

How to deploy a new version of the redirection Lambda

1. Package and upload to S3 a ZIP for the Lambda definition

   $ cd edge-lambda/
   $ yarn uploadToS3
   ...
   Finished uploading dist/wellcome_library_redirect.zip to s3://wellcomecollection-edge-lambdas/wellcome_library/wellcome_library_redirect.zip

   (Note: this automatically happens whenever new code is pushed to the main branch.)

2. Apply the Terraform changes:

   $ cd terraform/
   
   $ terraform plan -out=terraform.plan
   # review the changes
   
   $ terraform apply terraform.plan

   This will deploy the new version of the redirects to the staging domains. The new versions will be returned as an output:

   stage_lambda_function_versions = {
     "archive" = "28"
     "blog" = "45"
     "encore" = "24"
     "passthru" = "61"
     "wellcomelibrary" = "80"
   }
   

   We have multiple versions of the Lambda@Edge functions. When you upload a new zip package and run Terraform, it creates a new version. The staging domains always use the latest version, whereas the prod domains use a pinned version.

3. Test the redirects in staging:

   $ cd edge-lambda/
   $ yarn testRedirectsStage

4. Update the versions of the Lambda functions in prod in lambda_versions.tf, using the versions output from Terraform above. Then do another Terraform plan/apply.

5. Test the redirects in prod:

   $ cd edge-lambda/
   $ yarn testRedirects