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HAProxy - Load balancer
8a6cc6e3ea
When a TCP frontend uses an HTTP backend, the stream is automatically
upgraded and it results in a similar behavior as if a switch-mode http
rule was evaluated since stream_set_http_mode() gets called in both
situations and minimal HTTP analyzers are set.
In the current implementation, some postparsing checks are generating
errors or warnings when the frontend is in TCP mode with some HTTP options
set and no upgrade is expected (no switch-rule http). But as you can guess,
unfortunately this leads in issues when such "HTTP" only options are used
in a frontend that has implicit switching rules (that is, when the
frontend uses an HTTP backend for example), because in this case the
PR_O_HTTP_UPG will not be set, so the postparsing checks will consider
that some options are not relevant and will raise some warnings.
Consider the following example:
backend back
mode http
server s1 git.haproxy.org:80
frontend front
mode tcp
bind localhost:8080
http-request set-var(txn.test) str(TRUE),debug(WORKING,stderr)
use_backend back
By starting an haproxy instance with the above example conf, we end up
having this warning:
[WARNING] (400280) : config : 'http-request' rules ignored for frontend 'front' as they require HTTP mode.
However, by making a request on the frontend, we notice that the request
rules are still executed, and that's because the stream is effectively
upgraded as a result of an implicit upgrade:
[debug] WORKING: type=str <TRUE>
So this confirms the previous description: since implicit and explicit
upgrades result in approximately the same behavior on the frontend side,
we should consider them both when doing postparsing checks.
This is what we try to address in the following commit: PR_O_HTTP_UPG
flag is now more generic in the sense that it refers to either implicit
(through default_backend or use_backend rules) or explicit (switch-mode
rules) upgrades. Indeed, everytime an HTTP or dynamic backend (where the
mode cannot be assumed during parsing) is encountered in default_backend
directive or use_backend rules, we explicitly position the upgrade flag
so that further checks that depend on the proxy being in HTTP context
don't report false warnings.
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The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)