[GitHub] [apisix] kwanhur commented on issue #5451: request help: Does response-rewrite plugin support partial or regular substitution

[GitBox <gi...@apache.org>]

kwanhur commented on issue #5451:
URL: https://github.com/apache/apisix/issues/5451#issuecomment-1063801567


   Above the conversation, I got these information:
   
   Target: support specify content-type to filter, substitute response body by matching specific regex(fixed string as well) with replacement.
   > regex mode supports to replace all or once, and case-sensitive or not
   
   Solution: 
   Properties table
   | name | description | type | default |
   | -----  | ----------- | ----  | ------- |
   | filter_type | which response content-type matched | array | "text/plain" |
   | filter_pattern | pattern to match response body, could be regex | string | |
   | filter_replace | substitution content | string | |
   | filter_options | options for regex, detail see [here](https://github.com/openresty/lua-nginx-module#ngxrematch) | string | |
   | filter_kind | regex or completely substitute mode, range [1,2] 1-completely 2-regex | integer | 1 |
   | filter_scope | regex substitute once or global, range [1,2], 1-once 2-global | integer | 2 |
   
   Main steps:
   * step 1: check `conf.filter_kind`, equals to 1 then fallback to completely substitute, otherwise goto regex substitute(both in header_filter and body_filter).
   * step 2: at `header_filter` phase, check match `conf.filter_type` or not, if not then return, otherwise then mark `ctx.response_rewrite_matched` true.
   * step 3: at `body_filter` phase, `conf.filter_pattern` empty or if not `ctx.response_rewrite_matched` then return, otherwise `check conf.filter_scope`: scope 1 use `ngx.re.sub`, scope 2 use `ngx.re.gsub`.
   * step 4. substitution: 
   ```lua
   local body = ngx.arg[1]
   ngx.arg[1] = sub(conf.filter_pattern, conf.filter_replace, conf.filter_options)
   ```
   * step 5: mark eof
   ```lua
   ngx.arg[2] = true
   ```
   
   Any advices welcome :-).


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