'http-response cache-store icons if { path_beg /icons }' produces crashes and/or random behavior

[PiBa-NL]

Hello Chad, List,

Thanks for the nice article 
https://www.haproxy.com/blog/introduction-to-haproxy-acls/

However one of the examples that shows how to use cache-store seems flawed..

Attached ive made a little varnishtest, that:

- fails to run success-full when repeated 100 times with the path_beg 
acl on 1.8.14 (some requests are send twice to the s1 server, which 
stops listening after 1..) but its about 6% of runs that fails..

- produces core dumps with 1.9-dev4-1ff7633

Using the var(txn.path) instead it succeeds on both versions.

I think its important to 'fix' the article (and perhaps include the 
cache section declaration also), and perhaps investigate why haproxy 
does seem to try and process the fetch it warns about on startup that it 
would/should never match..

Regards,

PiBa-NL (Pieter)

# Checks that basic cache is working

varnishtest "Checks that basic cache is working"
feature ignore_unknown_macro

server s1 {
    rxreq
    txresp -bodylen 50
} -start

syslog Slg_1 -level notice {
    recv
    expect ~ "Proxy fe1 started"
    recv
    expect ~ "Proxy b1 started"
    recv info
    expect ~ "fe1 b1/srv1"
    recv info
    expect ~ "fe1 b1/<CACHE>"
    recv info
    expect ~ "fe1 b1/<CACHE>"
    recv info
    expect ~ "fe1 b1/<CACHE>"
} -start

haproxy h1 -conf {
  global
    #nbthread 3
    log ${Slg_1_addr}:${Slg_1_port} local0
    #log :1514 local0
    #nokqueue
    stats socket /tmp/haproxy.socket level admin
    #log /tmp/log local0

  defaults
    mode http
    #option dontlog-normal
    log global
    option httplog
    timeout connect         3s
    timeout client          4s
    timeout server          4s

  cache icons
    total-max-size 10
    max-age 60

  frontend fe1
    bind "fd@${fe_1}"
    default_backend b1

  backend b1
    http-request set-var(txn.MyPath) path

    #acl WeCanSafelyCacheThatFile var(txn.MyPath) -m beg /icons/
    acl WeCanSafelyCacheThatFile path_beg /icons/
    
    http-request cache-use icons if WeCanSafelyCacheThatFile
    http-response cache-store icons if WeCanSafelyCacheThatFile
    http-response add-header CacheResponse TRUE if WeCanSafelyCacheThatFile

    server srv1 ${s1_addr}:${s1_port}

} -start

client c1 -connect ${h1_fe_1_sock} {
  timeout 5
    txreq -url /icons/
    rxresp
    expect resp.status == 200

    txreq -url /icons/
    rxresp
    expect resp.status == 200
} -repeat 2 -run

syslog Slg_1 -wait