Nginx processes HTTP requests in multiple phases. In each of the phases there might be 0 or more handlers called. In the Nginx source code phases have specific constants associated with them. Here is a list of all phases:
NGX_HTTP_SERVER_REWRITE_PHASE — the phase of request URI transformation on virtual server level;
NGX_HTTP_FIND_CONFIG_PHASE — the phase of configuration location lookup;
NGX_HTTP_REWRITE_PHASE — the phase of request URI transformation on location level;
NGX_HTTP_POST_REWRITE_PHASE — request URI transformation post-processing phase;
NGX_HTTP_PREACCESS_PHASE — access restrictions check preprocessing phase;
NGX_HTTP_ACCESS_PHASE — access restrictions check phase;
NGX_HTTP_POST_ACCESS_PHASE — access restrictions check post-processing phase;
NGX_HTTP_TRY_FILES_PHASE — try_files directive processing phase;
NGX_HTTP_CONTENT_PHASE — content generation phase;
NGX_HTTP_LOG_PHASE — logging phase.
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