Using Haproxy maps to select backend, force HTTPS and set HSTS header

It’s possible to use string maps to simplify Haproxy configuration files. Map files are read on startup and its values stored in a tree for fast lookups.

This example uses map files to

• select backend
• force redirect to HTTPS based on domain
• set HSTS header

Example

./test.sh

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$ curl -siH Host: hello.example.org http://localhost:8080

HTTP/1.1 200 OK
Date: Fri, 15 Nov 2019 09:33:53 GMT
Content-Type: text/plain
Content-Length: 7
Request-Header-Host: hello.example.org
Request-Backend-Found: be_hello

hello!
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$ curl -skiH Host: hello.example.org https://localhost:8443

HTTP/1.1 200 OK
Date: Fri, 15 Nov 2019 09:33:53 GMT
Content-Type: text/plain
Content-Length: 7
Request-Header-Host: hello.example.org
Request-Backend-Found: be_hello
Strict-Transport-Security: include_subdomains; preload; max-age=31536000;

hello!
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$ curl -siH Host: world.example.org http://localhost:8080

HTTP/1.1 302 Found
Cache-Control: no-cache
Content-length: 0
Location: https://world.example.org/

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$ curl -skiH Host: world.example.org https://localhost:8443

HTTP/1.1 200 OK
Date: Fri, 15 Nov 2019 09:33:53 GMT
Content-Type: text/plain
Content-Length: 7
Request-Header-Host: world.example.org
Request-Backend-Found: be_world

world!
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Stats

The stats page can be accessed on http://localhost:63661/haproxy?stats.