diff --git a/management/daemon.py b/management/daemon.py index 1099a596..bc19e2ec 100755 --- a/management/daemon.py +++ b/management/daemon.py @@ -1,10 +1,10 @@ #!/usr/bin/python3 import os, os.path, re, json - +import subprocess from functools import wraps -from flask import Flask, request, render_template, abort, Response, send_from_directory +from flask import Flask, request, render_template, abort, Response, send_from_directory, make_response import auth, utils from mailconfig import get_mail_users, get_mail_users_ex, get_admins, add_mail_user, set_mail_password, remove_mail_user @@ -507,6 +507,81 @@ def munin(filename=""): if filename == "": filename = "index.html" return send_from_directory("/var/cache/munin/www", filename) +# MUNIN CGI-GRAPH + +@app.route('/munin/cgi-graph/') +@app.route('/munin/cgi-graph/') +@authorized_personnel_only +def munin_cgi(filename=""): + """ Relay munin cgi dynazoom requests + + /usr/lib/munin/cgi/munin-cgi-graph is a perl cgi script in the munin package + that is responsible for generating binary png images _and_ associated HTTP + headers based on parameters in the requesting URL. All output is written + to stdout which munin_cgi splits into response headers and binary response + data. + + munin-cgi-graph reads environment variables as well as passed input to determin + what it should do. It expects a path to be in the env-var PATH_INFO, and a + querystring to be in the env-var QUERY_STRING as well as passed as input to the + command. + + munin-cgi-graph has several failure modes. Some write HTTP 404 Status headers + and others return nonzero exit codes. munin_cgi has some basic handling, and + logs errors to app.logger. + + = Reasoning = + Situating munin_cgi between the user-agent and munin-cgi-graph enables keeping + the cgi script behind mailinabox's auth mechanisms and avoids additional + support infrastructure like spawn-fcgi. + + = Configuration = + A single configuration change is all that is required to enable the + functionality of munin_cgi. In the munin.conf file (/etc/munin/munin.conf) add + the following line above your server listings: + `cgiurl_graph /admin/munin/cgi-graph` + This will tell munin to override the default path for dynazoom requests. + """ + + COMMAND = 'su - munin --preserve-environment --shell=/bin/bash -c "/usr/lib/munin/cgi/munin-cgi-graph \'%s\'"' + # su changes user, we use the munin user here + # --preserve-environment retains the environment, which is where Popen's `env` data is + # --shell=/bin/bash ensures the shell used is bash + # -c "/usr/lib/munin/cgi/munin-cgi-graph" passes the command to run as munin + # \'%s\' is a placeholder for where the request's querystring will be added + + if filename == "": + return ("a path must be specified", 404) + + query_str = request.query_string.decode("utf-8", 'ignore') + + env = {'PATH_INFO': '/%s/' % filename, 'QUERY_STRING': query_str} + cmd = COMMAND % (query_str if not query_str.startswith('&') else query_str[1:]) + process = subprocess.Popen(cmd, env=env, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True) + stdout, stderr = process.communicate() + + if process.returncode != 0: + # nonzero returncode indicates error + app.logger.error("munin_cgi: munin-cgi-graph returned nonzero exit code, %s", process.returncode) + return ("error processing graph image", 500) + + # /usr/lib/munin/cgi/munin-cgi-graph returns both headers and binary png when successful. + # Per http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html PNG files always start + # with the same 8 bytes (137 80 78 71 13 10 26 10) or b'\x89PNG\r\n\x1a\n' So we split + # the output of munin-cgi-graph where the PNG begins + bin_start = stdout.find(b'\x89PNG\r\n\x1a\n') + str_headers = stdout[:bin_start].decode("utf-8") + # decode the byte str containing response headers + bin_image = stdout[bin_start:] + response = make_response(bin_image) + for line in str_headers.splitlines(): + if line: + name, value = line.split(':',1) + response.headers[name] = value + if 'Status' in response.headers and '404' in response.headers['Status']: + app.logger.warning("munin_cgi: munin-cgi-graph returned 404 status code. PATH_INFO=%s", env['PATH_INFO']) + return response + # APP if __name__ == '__main__': diff --git a/setup/munin.sh b/setup/munin.sh index 0cee9bad..0f2dec04 100755 --- a/setup/munin.sh +++ b/setup/munin.sh @@ -19,6 +19,9 @@ tmpldir /etc/munin/templates includedir /etc/munin/munin-conf.d +# path dynazoom uses for requests +cgiurl_graph /admin/munin/cgi-graph + # a simple host tree [$PRIMARY_HOSTNAME] address 127.0.0.1