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126 lines
3.8 KiB
Plaintext
126 lines
3.8 KiB
Plaintext
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There has been a lot of confusion during the development because of the
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backends and frontends.
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What we want :
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- being able to still use a listener as it has always been working
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- being able to write a rule stating that we will *change* the backend when we
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match some pattern. Only one jump is allowed.
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- being able to write a "use_filters_from XXX" line stating that we will ignore
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any filter in the current listener, and that those from XXX will be borrowed
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instead. A warning would be welcome for options which will silently get
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masked. This is used to factor configuration.
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- being able to write a "use_backend_from XXX" line stating that we will ignore
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any server and timeout config in the current listener, and that those from
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XXX will be borrowed instead. A warning would be welcome for options which
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will silently get masked. This is used to factor configuration.
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Example :
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---------
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| # frontend HTTP/80
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| listen fe_http 1.1.1.1:80
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| use_filters_from default_http
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| use_backend_from appli1
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| # frontend HTTPS/443
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| listen fe_https 1.1.1.1:443
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| use_filters_from default_https
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| use_backend_from appli1
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| # frontend HTTP/8080
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| listen fe_http-dev 1.1.1.1:8080
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| reqadd "X-proto: http"
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| reqisetbe "^Host: www1" appli1
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| reqisetbe "^Host: www2" appli2
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| reqisetbe "^Host: www3" appli-dev
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| use_backend_from appli1
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| # filters default_http
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| listen default_http
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| reqadd "X-proto: http"
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| reqisetbe "^Host: www1" appli1
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| reqisetbe "^Host: www2" appli2
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| # filters default_https
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| listen default_https
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| reqadd "X-proto: https"
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| reqisetbe "^Host: www1" appli1
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| reqisetbe "^Host: www2" appli2
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| # backend appli1
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| listen appli1
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| reqidel "^X-appli1:.*"
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| reqadd "Via: appli1"
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| balance roundrobin
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| cookie app1
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| server srv1
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| server srv2
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| # backend appli2
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| listen appli2
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| reqidel "^X-appli2:.*"
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| reqadd "Via: appli2"
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| balance roundrobin
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| cookie app2
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| server srv1
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| server srv2
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| # backend appli-dev
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| listen appli-dev
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| reqadd "Via: appli-dev"
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| use_backend_from appli2
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Now we clearly see multiple things :
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------------------------------------
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- a frontend can EITHER have filters OR reference a use_filter
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- a backend can EITHER have servers OR reference a use_backend
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- we want the evaluation to cross TWO levels per request. When a request is
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being processed, it keeps track of its "frontend" side (where it came
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from), and of its "backend" side (where the server-side parameters have
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been found).
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- the use_{filters|backend} have nothing to do with how the request is
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decomposed.
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Conclusion :
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------------
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- a proxy is always its own frontend. It also has 2 parameters :
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- "fi_prm" : pointer to the proxy holding the filters (itself by default)
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- "be_prm" : pointer to the proxy holding the servers (itself by default)
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- a request has a frontend (fe) and a backend (be). By default, the backend
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is initialized to the frontend. Everything related to the client side is
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accessed through ->fe. Everything related to the server side is accessed
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through ->be.
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- request filters are first called from ->fe then ->be. Since only the
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filters can change ->be, it is possible to iterate the filters on ->be
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only and stop when ->be does not change anymore.
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- response filters are first called from ->be then ->fe IF (fe != be).
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When we parse the configuration, we immediately configure ->fi and ->be for
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all proxies.
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Upon session creation, s->fe and s->be are initialized to the proxy. Filters
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are executed via s->fe->fi_prm and s->be->fi_prm. Servers are found in
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s->be->be_prm.
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