get many documents from couchdb, stream to a single response

dbproxy.lua

local cjson = require 'cjson'
local forward_headers = ngx.req.get_headers()
local body = ngx.req.read_body()
local query_args = ngx.req.get_query_args() -- then json-decode all the values
local post_args = ngx.req.get_body_data()
local db = ngx.var.db

for k, v in pairs(query_args) do
    query_args[k] = cjson.decode(v)
end

local json = cjson.decode(post_args)

ngx.header.content_type = 'application/json'

-- don't want attachments as mime
ngx.req.set_header('accept', 'application/json') 

ngx.say('[')
for i,v in ipairs(json.docs) do
    local id = v['id']
    local args = {}
    v['id'] = nil
    -- combine query string arguments and per-item arguments
    for k,v in pairs(query_args) do
        args[k] = v
    end
    for k,v in pairs(v) do
        args[k] = v
    end
    local subreq = ngx.location.capture('/db/' .. db .. '/' .. id, {args=args})
    ngx.say(subreq.body)
    if i < #json.docs then
        ngx.say(',')
    end
end
ngx.say(']')

nginx config

# nginx reverse proxy config including new lua-powered endpoint

lua_code_cache off; # for debug only

location ~ ^/db/(.*)/_new_endpoint$ {
    set $db $1;
    content_by_lua_file 'dbproxy.lua';
}

location /db {
    rewrite /db/(.*) /$1 break;
    proxy_buffering off;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_set_header Host $proxy_host;
    proxy_pass http://localhost:5984;
    proxy_redirect http://localhost:5984 http://$host/db;
}

usage

import requests, json
data = json.dumps({'docs':[{'id':'foo'}, {'id':'bar'}, {'id':'quux', meta=False}]})
requests.post('http://localhost/db/pouch/_new_endpoint?meta=true&open_revs="all"&revs_info=true', data=data).json()