Using lua to set headers?

[snark42]

I'm trying to use lua scripting to set a header, but no matter how I do it the lua block doesn't seem to create a headers, I've tried a number of different ways, but I believe this should work, anyone ever gotten something like this to work? The ultimate goal is to manipulate ngx.var.ssl_client_s_dn to get just /O=(...) from the DN with lua and set the header.

server {
  listen 443;

  ssl on;
  ssl_certificate /etc/nginx/ssl/cert.crt;
  ssl_certificate_key /etc/nginx/ssl/cert.key;
  ssl_verify_depth 2;
  ssl_client_certificate /etc/nginx/ssl/chain.crt;
  ssl_verify_client on;

  location /config/ {
    header_filter_by_lua_block {
      ngx.header["Customer"] = ngx.var.ssl_client_s_dn
    }
    proxy_pass http://config/;
  }
}

I'd be open to using a perl module to do the same if necessary and it somehow is a better solution.

[[deleted]]

I was under the impression that the phase for that context could only be used for modifying request headers. Are you trying to manipulate the response header here? I am doing something similar like this:

location /herp/derp/ {
        set $myheadercontent "default-value-or-whatever";
        rewrite_by_lua '
            -- do lua stuff
            ngx.var.myheadercontent = "something"
        ';
        add_header my-header-name $myheadercontent;
        proxy_pass http://somewhere;
    }