Delete NGINX cached items from a PURGE request

purge.lua

-- Tit Petric, Monotek d.o.o., Thu 27 Oct 2016 10:43:38 AM CEST
--
-- Delete nginx cached assets with a PURGE request against an endpoint
--

local md5 = require 'md5'

function file_exists(name)
        local f = io.open(name, "r")
        if f~=nil then io.close(f) return true else return false end
end

function explode(d, p)
        local t, ll
        t={}
        ll=0
        if(#p == 1) then return {p} end
                while true do
                        l=string.find(p, d, ll, true) -- find the next d in the string
                        if l~=nil then -- if "not not" found then..
                                table.insert(t, string.sub(p, ll, l-1)) -- Save it in our array.
                                ll=l+1 -- save just after where we found it for searching next time.
                        else
                                table.insert(t, string.sub(p, ll)) -- Save what's left in our array.
                                break -- Break at end, as it should be, according to the lua manual.
                        end
                end
        return t
end

function cache_filename(cache_path, cache_levels, cache_key)
        local md5sum = md5.sumhexa(cache_key)
        local levels = explode(":", cache_levels)
        local filename = ""

        local index = string.len(md5sum)
        for k, v in pairs(levels) do
                local length = tonumber(v)
                -- add trailing [length] chars to index
                index = index - length;
                filename = filename .. md5sum:sub(index+1, index+length) .. "/";
        end
        if cache_path:sub(-1) ~= "/" then
                cache_path = cache_path .. "/";
        end
        filename = cache_path .. filename .. md5sum
        return filename
end

function purge(filename)
        if (file_exists(filename)) then
                os.remove(filename)
        end
end

if ngx ~= nil then
        local cache_key = ngx.var.lua_purge_upstream .. ngx.var.request_uri
        local filename = cache_filename(ngx.var.lua_purge_path, ngx.var.lua_purge_levels, cache_key)
        purge(filename)
        ngx.say("OK")
        ngx.exit(ngx.OK)
end

great work! but i made some change

local md5 = require 'md5' local md5sum = md5.sumhexa(cache_key)
can be replaced by
local md5 = ngx.md5 local md5sum = md5(cache_key)
will never require module md5

Great work! Much thanks.

Noticed that the md5 of the proxy_cache_key does not match the file name when there is a Vary header present. Is it calculated differently in presence of Vary headers?

proxy_ignore_headers Vary

…

On Tue, 28 Apr 2020 at 22:50, e1fa16a4ba9c7d32 ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Great work! Much thanks. Noticed that the md5 of the proxy_cache_key does not match the file name when there is a Vary header present. Is it calculated differently in presence of Vary headers? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/ed6ec548af160e82c650cf39074878fb#gistcomment-3273817>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABY7EBQBZPTH36UIBJ2G3DRO46R7ANCNFSM4JYP46RA> .