MINOR: acl: add the new "env()" fetch method to retrieve an environment variable

This is useful in order to take different actions across restarts without
touching the configuration (eg: soft-stop), or to pass some information
such as the local host name to the next hop.
This commit is contained in:
Willy Tarreau 2013-06-12 21:34:28 +02:00
parent 3c4beb1feb
commit 595ec54d38
2 changed files with 37 additions and 2 deletions

View File

@ -8795,6 +8795,20 @@ connslots([<backend>]) : integer
then this fetch clearly does not make sense, in which case the value returned
will be -1.
env(<name>) : string
Returns a string containing the value of environment variable <name>. As a
reminder, environment variables are per-process and are sampled when the
process starts. This can be useful to pass some information to a next hop
server, or with ACLs to take specific action when the process is started a
certain way.
Examples :
# Pass the Via header to next hop with the local hostname in it
http-request add-header Via 1.1\ %[env(HOSTNAME)]
# reject cookie-less requests when the STOP environment variable is set
http-request deny if !{ cook(SESSIONID) -m found } { env(STOP) -m found }
fe_conn([<frontend>]) : integer
Returns the number of currently established connections on the frontend,
possibly including the connection being evaluated. If no frontend name is

View File

@ -1980,6 +1980,26 @@ smp_fetch_false(struct proxy *px, struct session *s, void *l7, unsigned int opt,
return 1;
}
/* retrieve environment variable $1 as a string */
static int
smp_fetch_env(struct proxy *px, struct session *s, void *l7, unsigned int opt,
const struct arg *args, struct sample *smp)
{
char *env;
if (!args || args[0].type != ARGT_STR)
return 0;
env = getenv(args[0].data.str.str);
if (!env)
return 0;
smp->type = SMP_T_CSTR;
smp->data.str.str = env;
smp->data.str.len = strlen(env);
return 1;
}
/************************************************************************/
/* All supported sample and ACL keywords must be declared here. */
@ -1991,8 +2011,9 @@ smp_fetch_false(struct proxy *px, struct session *s, void *l7, unsigned int opt,
* instance IPv4/IPv6 must be declared IPv4.
*/
static struct sample_fetch_kw_list smp_kws = {{ },{
{ "always_false", smp_fetch_false, 0, NULL, SMP_T_BOOL, SMP_USE_INTRN },
{ "always_true", smp_fetch_true, 0, NULL, SMP_T_BOOL, SMP_USE_INTRN },
{ "always_false", smp_fetch_false, 0, NULL, SMP_T_BOOL, SMP_USE_INTRN },
{ "always_true", smp_fetch_true, 0, NULL, SMP_T_BOOL, SMP_USE_INTRN },
{ "env", smp_fetch_env, ARG1(1,STR), NULL, SMP_T_CSTR, SMP_USE_INTRN },
{ /* END */ },
}};