Enable Router to be configured with multiple domains #188
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I think you might need to update the PR description to match the commit too :) |
Problem ------- During the migration to ECS, Replatforming intends to run router in ECS and EC2, using the same backing database managed by Router API, hosted in EC2. One problem with this approach is that ECS and EC2 apps are served at different domains (as below), - https://calendars.integration.govuk-internal.digital/ - http://calendars.mesh.govuk-internal.digital/ Router looks up the entire backend_url from its database. This currently makes it impossible to run two different Router applications which serve different domains, but use the same database. Solution -------- Rather than store the backend_url for a backend in Router API's database, we'll provide backend URLs as environment variables such as ``` BACKEND_URL_content-store=https://content-store.gov.uk/ BACKEND_URL_search-api=https://search.gov.uk/ ``` If an environment variable matching a backend_id is set Router will use the value of the variable instead of the FQDN backend_url stored in the DB. This change should have no impact on the current platform since we won't set any new environment variables there. As it is trivial to bring up new containers in ECS with different sets of environment variables, this will enable us to make router work across domains while using the same database (for workspaces). Migration path: 1. Push this change out 2. Add env var for backends to router instances in ECS **Other approaches** * Provide an env var for the host domain and add subdomains to backends in Router API (overly complex) * write duplicate backend records to the db (unnecessary) Trello: https://trello.com/c/qtAZfkjg/403-work-out-whether-we-can-make-router-work-with-multiple-domains-and-a-single-database Design doc: https://docs.google.com/document/d/147FSn4sd80iGZ1KxcJ7OYG2cW_uY-Gc7e7laLhkkMJo/edit#
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@richardTowers thanks for your feedback! I've improved the test and formatted. |
richardTowers
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This will enable router to route requests to instances in its own mesh. This follows on from this PR: alphagov/router#188 I've added the other backends in as placeholders, acquired using this RouterAPI query: ```ruby Route.collection.aggregate([ {"$group" => {"_id" => "$backend_id", "count" => {"$sum" => 1}}} ]).each { |res| puts "#{res["_id"]}: #{res["count"]}" } ```
bilbof
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This will enable router to route requests to instances in its own mesh. This follows on from this PR: alphagov/router#188 I've added the other backends in as placeholders, acquired using this RouterAPI query: ```ruby Route.collection.aggregate([ {"$group" => {"_id" => "$backend_id", "count" => {"$sum" => 1}}} ]).each { |res| puts "#{res["_id"]}: #{res["count"]}" } ```
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Problem
During the migration to ECS, Replatforming intends to run router in ECS and EC2, using the same backing database managed by Router API, hosted in EC2.
One problem with this approach is that ECS and EC2 apps are served at different domains (as below):
Router looks up the entire backend_url from its database. This currently makes it impossible to run two different Router applications which serve different domains, but use the same database.
Solution
Rather than store the backend_url for a backend in Router API's database, we'll provide backend URLs as environment variables such as
If an environment variable matching a backend_id is set Router will use the value of the variable instead of the FQDN backend_url stored in the DB.
This change should have no impact on the current platform since we won't set any new environment variables there.
As it is trivial to bring up new containers in ECS with different sets of environment variables, this will enable us to make router work across domains while using the same database (for workspaces).
Migration path:
Other approaches
Trello: https://trello.com/c/qtAZfkjg/403-work-out-whether-we-can-make-router-work-with-multiple-domains-and-a-single-database
Design doc: https://docs.google.com/document/d/147FSn4sd80iGZ1KxcJ7OYG2cW_uY-Gc7e7laLhkkMJo/edit#