Keeping a process running with Flock and Cron

We've got a few processes here that aren't system services, but need to be running in the background and should be restarted if they die. However, this method can also be used for a cron that often runs past it's normal re-execution time (say a every 5 min cron that sometimes runs for 7min). It will prevent multiple executions from running simultaneously.

First off, in your crontab, you can add a line like this:

* * * * * flock -x -n /tmp/awesomenessRunning.lock -c "/usr/local/bin/myAwesomeScript.sh" >/dev/null 2>&1

What happens here is fairly straight forward:

• Every minute, flock executes your script in this case "/usr/local/bin/myAwesomeScript.sh"
• flock opens up an exclusive write lock on the lock file, here named "/tmp/awesomenessRunning.lock". When it's done executing, it'll release the lock.
• The next time this cron runs, flock will attempt to again, get an exclusive lock on that lock file... but it can't if that script is still running, so it'll give up and try again next time the cron runs.

Now, generally, if I'm doing this as a systems level item, I'll put the following in a file named for the job or what the job is doing and drop it in /etc/cron.d/. All the files there will get compiled together into the system cron, which helps other admins (or your later self) to find and disable it later. If you do that, remember to stick the user to execute the cron as between the *'s and the flock!

Resizing Online Disks in Linux with LVM and No Reboots

When we set this up, we only had a 16GB primary disk... Plenty of space. Until you start to write lots of logs and data... and then it fills up quick. So let's talk about how to resize an LVM based partition on a live server without reboots... Reboots are for Windows! This system is a CentOS 6.x machine running in VMWare 5.x that's currently got a 16GiB VMDK based drive. Let's see what we've got to work with:

$ df -h
Filesystem                                         Size  Used Avail Use% Mounted on
/dev/mapper/myfulldisk--vg-root                     12G   11G     0 100% /
none                                               4.0K     0  4.0K   0% /sys/fs/cgroup
udev                                               7.4G  4.0K  7.4G   1% /dev
tmpfs                                              1.5G  572K  1.5G   1% /run
none                                               5.0M     0  5.0M   0% /run/lock
none                                               7.4G     0  7.4G   0% /run/shm
none                                               100M     0  100M   0% /run/user
/dev/sda1                                          236M   37M  187M  17% /boot
/dev/sdc1                                          246G   44G  190G  19% /data

Hmm... time to get on this then. Now, luckily we're running in VMWare. A quick edit to our VM to enlarge the VMDK (not covered in this how-to) will fix this... First, what device are we talking about?

$ dmesg|grep sd
[    1.562363] sd 2:0:0:0: Attached scsi generic sg1 type 0
[    1.562384] sd 2:0:0:0: [sda] 33554432 512-byte logical blocks: (17.1 GB/16.0 GiB)
[    1.562425] sd 2:0:0:0: [sda] Write Protect is off
[    1.562426] sd 2:0:0:0: [sda] Mode Sense: 61 00 00 00
[    1.562460] sd 2:0:0:0: [sda] Cache data unavailable
[    1.562461] sd 2:0:0:0: [sda] Assuming drive cache: write through
[    1.563331] sd 2:0:0:0: [sda] Cache data unavailable
[    1.563451] sd 2:0:1:0: Attached scsi generic sg2 type 0
[    1.563452] sd 2:0:1:0: [sdb] 8388608 512-byte logical blocks: (4.29 GB/4.00 GiB)
[    1.563479] sd 2:0:1:0: [sdb] Write Protect is off
[    1.563481] sd 2:0:1:0: [sdb] Mode Sense: 61 00 00 00
[    1.563507] sd 2:0:1:0: [sdb] Cache data unavailable
[    1.563508] sd 2:0:1:0: [sdb] Assuming drive cache: write through
[    1.563755] sd 2:0:2:0: Attached scsi generic sg3 type 0
[    1.563881] sd 2:0:2:0: [sdc] 524288000 512-byte logical blocks: (268 GB/250 GiB)
[    1.563942] sd 2:0:2:0: [sdc] Write Protect is off
[    1.563944] sd 2:0:2:0: [sdc] Mode Sense: 61 00 00 00
[    1.564008] sd 2:0:2:0: [sdc] Cache data unavailable
[    1.564010] sd 2:0:2:0: [sdc] Assuming drive cache: write through
[    1.564282] sd 2:0:2:0: [sdc] Cache data unavailable
[    1.564283] sd 2:0:2:0: [sdc] Assuming drive cache: write through
[    1.564360] sd 2:0:1:0: [sdb] Cache data unavailable
[    1.564362] sd 2:0:1:0: [sdb] Assuming drive cache: write through
[    1.564989] sd 2:0:0:0: [sda] Assuming drive cache: write through
[    1.571010]  sdb: sdb1
[    1.571426] sd 2:0:1:0: [sdb] Cache data unavailable
[    1.571514] sd 2:0:1:0: [sdb] Assuming drive cache: write through
[    1.571626] sd 2:0:1:0: [sdb] Attached SCSI disk
[    1.574181]  sda: sda1 sda2 < sda5 >
[    1.574797] sd 2:0:0:0: [sda] Cache data unavailable
[    1.574888] sd 2:0:0:0: [sda] Assuming drive cache: write through
[    1.575003] sd 2:0:0:0: [sda] Attached SCSI disk
[    1.579250]  sdc: sdc1
[    1.579805] sd 2:0:2:0: [sdc] Cache data unavailable
[    1.579944] sd 2:0:2:0: [sdc] Assuming drive cache: write through
[    1.580141] sd 2:0:2:0: [sdc] Attached SCSI disk
[    6.922330] Adding 4193276k swap on /dev/sdb1.  Priority:-1 extents:1 across:4193276k FS
[    7.137134] EXT4-fs (sda1): mounting ext2 file system using the ext4 subsystem
[    7.142419] EXT4-fs (sda1): mounted filesystem without journal. Opts: (null)
[    7.218150] EXT4-fs (sdc1): mounted filesystem with ordered data mode. Opts: (null)
[    7.384566] Installing knfsd (copyright (C) 1996 okir@monad.swb.de).

The first one is the 16GB drive in question. Take the number on that line and use it in the next step:

$ echo 1 > /sys/class/scsi_device/2\:0\:0\:0/device/rescan
$ dmesg |tail
[1918441.322362] sd 2:0:0:0: [sda] 209715200 512-byte logical blocks: (107 GB/100 GiB)
[1918441.322596] sd 2:0:0:0: [sda] Cache data unavailable
[1918441.330685] sd 2:0:0:0: [sda] Assuming drive cache: write through
[1918441.489622] sda: detected capacity change from 17179869184 to 1073741824

So, that's good, it sees our increased size. Now, lets enlarge that Volume Group. First we get info about the volume group.

$ vgdisplay
  --- Volume group ---
  VG Name               myfulldisk-vg
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               15.76 GiB
  PE Size               4.00 MiB
  Total PE              4034
  Alloc PE / Size       4028 / 15.73 GiB
  Free  PE / Size       6 / 24.00 MiB
  VG UUID               dv3URd-EVvz-oTwY-WiDW-RPt1-4rbD-FnPxxM

That '6' is only 24MiB. It doesn't see our new space yet. In order to get it to, we need to make a new partition of the right type, then add it to the volume group. We'll then end up with more Free PE's. Here we go:

$ fdisk /dev/sda
Command (m for help): p

Disk /dev/sda: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209715200 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000ade37

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      499711      248832   83  Linux
/dev/sda2          501758    33552383    16525313    5  Extended
/dev/sda5          501760    33552383    16525312   8e  Linux LVM

Command (m for help): n
Partition type:
   p   primary (1 primary, 1 extended, 2 free)
   l   logical (numbered from 5)
Select (default p): p
Partition number (1-4, default 3): 3
First sector (499712-209715199, default 499712): 33552384
Last sector, +sectors or +size{K,M,G} (33552384-209715199, default 209715199): 
Using default value 209715199

Command (m for help): t
Partition number (1-5): 3
Hex code (type L to list codes): 8e
Changed system type of partition 3 to 8e (Linux LVM)

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.

At this point you could reboot... but we're not going to. Even though this is our root drive which makes this a little trickier, it's nothing we can't fix:

$ partprobe /dev/sda

Hopefully, partprobe has found your new partition for you and enlightened the kernel with it's wisdom (or at least fresh load of zeros). Now we need to make it an available volume to use for expanding the disk. This consists of making it a 'Physical volume', and then adding that physical volume to the Volume Group containing the disk we want to expand.

$ pvcreate /dev/sda3
  Physical volume "/dev/sda3" successfully created
$ pvdisplay
  --- Physical volume ---
  PV Name               /dev/sda5
  VG Name               myfulldisk-vg
  PV Size               15.76 GiB / not usable 2.00 MiB
  Allocatable           yes 
  PE Size               4.00 MiB
  Total PE              4034
  Free PE               6
  Allocated PE          4028
  PV UUID               a3mhvZ-ogyk-ao4y-2JSM-KVfL-i9no-q0LAUk
   
  "/dev/sda3" is a new physical volume of "84.00 GiB"
  --- NEW Physical volume ---
  PV Name               /dev/sda3
  VG Name               
  PV Size               84.00 GiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               IpyjOU-1GDy-bTLL-U9kE-iSGP-BYg1-a25LIm
   
$ vgextend /dev/myfulldisk-vg /dev/sda3
  Volume group "myfulldisk-vg" successfully extended
$ vgdisplay
  --- Volume group ---
  VG Name               myfulldisk-vg
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               99.76 GiB
  PE Size               4.00 MiB
  Total PE              25538
  Alloc PE / Size       4028 / 15.73 GiB
  Free  PE / Size       21510 / 84.02 GiB
  VG UUID               dv3URd-EVvz-oTwY-WiDW-RPt1-4rbD-FnPxxM

Awesome, we now have 21510 free PE's that we can use... That's, apparently, 84.02GB in this case. Next up, we'll need to know what portion of the VG we need to extend. Looking back up at a 'df' output, and knowing our system, it says "root" in there. doing a quick ls of /dev/myfulldisk-vg/ shows that there's only really a choice between root" and "swap". So, knowing it's root we move on with:

$ lvextend -L95G /dev/myfulldisk-vg/root
  Extending logical volume root to 95.00 GiB
  Logical volume root successfully resized
$ df -h
Filesystem                                         Size  Used Avail Use% Mounted on
/dev/mapper/myfulldisk--vg-root                     12G   11G  114M  99% /
none                                               4.0K     0  4.0K   0% /sys/fs/cgroup
udev                                               7.4G  4.0K  7.4G   1% /dev
tmpfs                                              1.5G  576K  1.5G   1% /run
none                                               5.0M     0  5.0M   0% /run/lock
none                                               7.4G     0  7.4G   0% /run/shm
none                                               100M     0  100M   0% /run/user
/dev/sda1                                          236M   37M  187M  17% /boot
/dev/sdc1                                          246G   44G  190G  19% /data

Okay, the VG might be bigger, but no one else knows that. Because the filesystem ON the VG is still the same size, luckily there's a command for that too!

$ resize2fs /dev/myfulldisk-vg/root
resize2fs 1.42.9 (4-Feb-2014)
Filesystem at /dev/myfulldisk-vg/root is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 6
The filesystem on /dev/myfulldisk-vg/root is now 24903680 blocks long.

$ df -h
Filesystem                                         Size  Used Avail Use% Mounted on
/dev/mapper/myfulldisk--vg-root                     94G   11G   79G  12% /
none                                               4.0K     0  4.0K   0% /sys/fs/cgroup
udev                                               7.4G  4.0K  7.4G   1% /dev
tmpfs                                              1.5G  576K  1.5G   1% /run
none                                               5.0M     0  5.0M   0% /run/lock
none                                               7.4G     0  7.4G   0% /run/shm
none                                               100M     0  100M   0% /run/user
/dev/sda1                                          236M   37M  187M  17% /boot
/dev/sdc1                                          246G   44G  190G  19% /data

Ha, there we go! 79GB available, enjoy!

Running Custom SNMPd Checks in CentOS 6

I've been fighting with a problem between CentOS 5.x and CentOS 6.x SNMPD configs. In CentOS 5.x we have two lines in /etc/snmpd/snmpd.conf like the following:

exec 1.3.6.1.4.1.5001.100 mailq-check /usr/local/nagios/libexec/check_mailq -w2 -c4 -t7 
exec 1.3.6.1.4.1.5002.1 fscheck /bin/touch /opt/rocheck && /bin/touch /tmp/rocheck

They're simple commands that extend snmp. In CentOS 5.x this form is: "exec <return oid> <name> <command>" and when setup the command or script's output will be returned via snmpd to those that request the MIB/OID. All well and good, but copying this into the standard snmpd.conf file from CentOS 6 gave me nothing. running snmpd with verbose logging gave me nothing useful other than being able to see that it was being requested. Digging deeper, I found the following command and it's output:

# snmpwalk -v 2c 10.93.90.209 -c rsprod .1.3.6.1.4.1.2021.8
UCD-SNMP-MIB::extIndex.1 = INTEGER: 1
UCD-SNMP-MIB::extIndex.2 = INTEGER: 2
UCD-SNMP-MIB::extNames.1 = STRING: 1.3.6.1.4.1.5001.100
UCD-SNMP-MIB::extNames.2 = STRING: 1.3.6.1.4.1.5002.1
UCD-SNMP-MIB::extCommand.1 = STRING: mailq-check
UCD-SNMP-MIB::extCommand.2 = STRING: fscheck
UCD-SNMP-MIB::extResult.1 = INTEGER: 1
UCD-SNMP-MIB::extResult.2 = INTEGER: 1
UCD-SNMP-MIB::extOutput.1 = STRING: mailq-check: No such file or directory
UCD-SNMP-MIB::extOutput.2 = STRING: fscheck: No such file or directory
UCD-SNMP-MIB::extErrFix.1 = INTEGER: 0
UCD-SNMP-MIB::extErrFix.2 = INTEGER: 0
UCD-SNMP-MIB::extErrFixCmd.1 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.2 = STRING: 

Looking at this, it doesn't look like it's running my script "/usr/local/nagios/libexec/check_mailq -w2 -c4 -t7" but attempting to run the name "mailq-check". Of course, that isn't the script name+path, so it doesn't find it. Turns out that in CentOS 6, you don't use the oid portion:

exec mailq-check "/usr/local/nagios/libexec/check_mailq -w2 -c4 -t7 -Mpostfix"
exec fscheck "/bin/touch /opt/rocheck && /bin/touch /tmp/rocheck"

Which, when called with the same snmpwalk above, comes back as:

UCD-SNMP-MIB::extIndex.1 = INTEGER: 1
UCD-SNMP-MIB::extIndex.2 = INTEGER: 2
UCD-SNMP-MIB::extNames.1 = STRING: mailq-check
UCD-SNMP-MIB::extNames.2 = STRING: fscheck
UCD-SNMP-MIB::extCommand.1 = STRING: /usr/local/nagios/libexec/check_mailq -w2 -c4 -t7 -Mpostfix
UCD-SNMP-MIB::extCommand.2 = STRING: /bin/touch /opt/rocheck && /bin/touch /tmp/rocheck
UCD-SNMP-MIB::extResult.1 = INTEGER: 0
UCD-SNMP-MIB::extResult.2 = INTEGER: 0
UCD-SNMP-MIB::extOutput.1 = STRING: OK: mailq reports queue is empty|unsent=0;2;4;0
UCD-SNMP-MIB::extOutput.2 = STRING: 
UCD-SNMP-MIB::extErrFix.1 = INTEGER: 0
UCD-SNMP-MIB::extErrFix.2 = INTEGER: 0
UCD-SNMP-MIB::extErrFixCmd.1 = STRING: 
UCD-SNMP-MIB::extErrFixCmd.2 = STRING: 

Now, let me explain what all of these MIBs mean.

• extIndex.#
  The Index number of the command
• extNames.#
  The Name you gave the command. This is the first parameter you pass to exec
• extCommand.#
  The full command you had SNMPd call to return you this info. Second parameter you passed to exec
• extResult.#
  Exit Code from the command exec'd
• extOutput.#
  Raw output of the command exec'd
• extErrFix.#
  This is a bit that can be flipped by the client. Flipping this to a 1 kicks off the extErrFixCmd by SNMPd. Generally this is used to 'fix' and 'error' condition.
• extErrFixCmd.#
  The command to be executed by the SNMPd server

Writing a C/C++ App run from apache

A few weeks back I started wondering on ways to improve the performance of certain areas of my site (as I do periodically) and while I came across examples of PHP compilers in their many forms, I started wondering if I should just go whole hog and write some parts of the application right in C/C++. Sure, everyone is jumping on nodejs, but I've worked in both C and C++ languages before and while it has been sometime, I thought it might be an interesting exercise to try writing some of the back end processes in either one. After all, I'm running mysql as my db, and there are mysql c headers and api, so it should be fairly straight forward. I found quickly that some of this documentation was lacking. Sure I can create a C/C++ executable that'll give me info from my DB on demand, but getting it back to the requester was being a pain. Digging around and experimenting led me to finding a few things that I'd like to share here.

int MIMEHeader() { 
     cout << "Content-type: text/html" << endl << endl << endl; 
     cout << "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Strict//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd\">"<<endl; 
     cout <<"<HTML xlmns='http://www.w3.org/1999/xhtml' xml:lang='en' lang='en'>" <<endl;
}

int main() {
     MIMEHeader();
     cout<<">head<>/head><body>"<<endl;        
     cout<<"Hello World!"<<endl;    
     cout<<"</body>"<<endl;
     return TRUE;
}

First off, yes, you really do need three "endl"'s on the first line. One finishes the current line and the next to tell apache you really mean that this is html and it should serve it. The next two sets up the doctype and get things ready for you to output your info. Calling this function from our main function causes things to be ready for output. In the example here, we tack on the proverbial "Hello World" example.
The next step here is to get apache to proxy the output of our program to the end user's web browser. You'll need this block in your sections affected.

<Directory "/path/your/website/x">
     AllowOverride None
     Options ExecCGI
     Order allow,deny
     Allow from all
</Directory>
ScriptAlias /x /path/to/your/website/x

In the example, I used /x as my subdir of compiled code. So, resolving it would be "http://example.com/x/programName".

At this point you're good to go, and boy is it FAST. In my non-exhaustive testing, a simple App involving a MySQL query takes less than 1ms more than the actual MySQL query. Obviously, your results may vary. Here's the example C++ I wrote for a start before I started adding more fancy api type features to it. I compiled it on CentOS 5.4 with stock CentOS distributed MySQL 5.1:

// Compile this using:
// g++ -o mysqltest mysqltest.cpp -L/usr/lib64/mysql -lmysqlclient -I/usr/include/mysql && ./mysqltest
//

#include <iostream>
#include <mysql/mysql.h>

using namespace std;
MYSQL *connection, mysql;
MYSQL_RES *result;
MYSQL_ROW row;
int query_state;

int MIMEHeader() {
 cout << "Content-type: text/html"<<endl<<endl<<endl<<"<HTML><BODY><PRE>";
}

int Footer() { 
 cout << "</PRE></BODY></HTML>";
}

int main() {
 char * env;
 MIMEHeader();
 mysql_init(&mysql);
 connection = mysql_real_connect(&mysql,"localhost","myUs3r","myPa55word","myBookmarks",0,0,0);
 if (connection == NULL) { 
  cout << mysql_error(&mysql) << endl;
  return 1;
 } 
 query_state=mysql_query(connection,"select * from links where id like '%blogger.com';");
 if (query_state!=0) {
  cout << mysql_error(&mysql) << endl;
                return 1;
 }
 result = mysql_store_result(connection);
 cout << "<table>"<<endl;
 while  (( row = mysql_fetch_row(result)) != NULL ) {
  cout << "<tr><td>" << row[0] <<"</td><td>"<< row[1] <<"</td><td>"<< row[2] <<"</td></tr>"<<endl;
 }
 cout << "</table>"<<endl;
 Footer();
 mysql_free_result(result);
 mysql_close(connection);
 return 0;
}

Adding Swap Space in Linux Without a Reboot

So, let's say you've got a server running out of memory. Not just RAM, but swap too. Now, generally, there are a few well known ways to solve this issue.

• Close/Kill processes you don't need
• Reboot
• Add another swap partition
• Buy more RAM
• Buy more Hardware

Now, In our scenario, the first option isn't helping, the second one is just the nuclear option to the first. But we've got one huge process and it's not all active memory... it's just consuming a lot of RAM and Swap and we want it to succeed. Buying more RAM is the best idea, but this server won't take anymore, or we're not sure we'll have this workload often, so we can't justify wasting money on more hardware. We've gotta get creative before it fills up and gets OOM killed. Adding another swap partition is a great idea, but we're out of available disk partitions or drives to throw at it. However, we do have some free space on an existing partition, we can leverage that.

$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/md2               47G   11G   35G  23% /
/dev/hda1              99M   20M   74M  22% /boot

Alright, looking at a top or vmstat, we know we've got 4GB of RAM in here, and another 2GB of swap. Knowing the size of the process, we figure doubling that swap will give us plenty of overhead at the moment. Let's do this!

$ dd if=/dev/zero of=/newswap bs=32k count=64k

65536+0 records in
65536+0 records out
2147483648 bytes (2.1 GB) copied, 18.9618 seconds, 113 MB/s

$ ls -al /newswap
-rw-r--r-- 1 root root 2147483648 Nov 19 23:02 /newswap
$ mkswap /newswap
Setting up swapspace version 1, size = 2147479 kB
$ swapon /newswap

And that's it. A quick check should find that we now have another 2GB of swap space and a system that can breathe a little more.

Note: The size of the swap space is determined by the size of the file. 'bs' is the block size, and 'count' is the number of blocks. I generally stick to 32k or 64k block sizes and then adjust the count from there. 64k & 64k is 4GB, 64k and 128k is 8GB, etc.

Now, this won't stick after a reboot as is. If you'd like it to, I recommend changing the process a bit. It's the same until you've finished the mkswap command, after that instead of running swapon, open up the /etc/fstab in your favorite editor (vi /etc/fstab) and then add another swap line after the disk the file is on is listed like so:

/newswap         swap                    swap    defaults        0 0

Then you can run 'swapon -a' and it will mount ALL swap partitions.

Note: Swap automatically stripes across multiple swap partitions of the same priority. It might be useful to make swap partitions on multiple drives to allow for faster RAID-0 type speeds across drives!

Hope this helped someone out. I had to use it the other day and was able to save a long running process that was eating up RAM like candy. It finished a few hours after I put this fix in place. Since I don't run that process often, I simply removed the line from the /etc/fstab and the next time it rebooted, it was back to it's normal swap sizes. I then deleted the file and it was like nothing ever happened!

Cacti 0.8.8a and Plugins

Today I needed to install some plugins into my Cacti 0.8.8a install. Cacti has been a great graphing tool for many years here, and the 0.8.8a update has added a lot of cool things. One of them is the built in Plugin Architecture (Previous versions required you to install Cacti, then download the "PIA" and patch files and make manual edits to get it to work). However, being used to the old ways, I was having trouble using the "simple new way" and I didn't find much out in the wild about making it work. It really is simple! Just:

1. Download a plugin from somewhere like Here
2. Extract the contents of the tarball (it should make a subdirectory)
3. Move the subdirectory to the cacti/plugins/ directory (mine is /var/www/html/cacti/plugins/)
4. Open up Cacti in a browser
5. If you see Plugin Management on the left, skip the next step and just go there
6. Go to User Management, pick your user and check the box next to "Plugin Management".. refresh the page and then go to "Plugin Management" on the left menu.
7. You should see your plugin listed. Hit the arrow down button to install it, and then the arrow right to enable it!

NOTE: The problem I had is this: The directory your plugin is in (for instance, mine was "cacti/plugins/aggregate-0.7B2") CANNOT HAVE NON-ALPHA CHARACTERS.

So, basically, I followed all of these instructions, wondered where the heck my plugin was, and started scraping through code. I finally found the line that looks for available plugins had input_validate_input_regex(get_request_var("id"), "^([a-zA-Z0-9]+)$"); did I then realize, "Hey, maybe if I took that - and the . out of the filename..."

So I moved it, hit refresh on the Plugin Management page and saw my plugin appear.

PHPUnit 3.5.15 for Zend Framework ZF1 on CentOS

We're still running ZF1 here, and as the ZF2 update is no small body of work, we continue to need PHPUnit 3.5.15 in order to run our unit tests. I've found that this is not as straight forward as installing the latest version of PHPUnit (up to 3.7.24 as of this writing). It seems PHPUnit versions of 3.6+ are geared toward ZF2 development and testing and no longer work AT ALL with ZF1. So, before you think "I can just run pear install phpunit/PHPUnit, and be good!" and then bang your head against the desk trying to get it to work right, this is the sequence of commands I've gone through to install this on CentOS 5.x and 6.x hosts.

pear channel-discover pear.symfony-project.com
pear channel-discover components.ez.no
pear install --alldeps pear.phpunit.de/DbUnit-1.0.3
pear install phpunit/PHPUnit_TokenStream-1.1.5 ??
pear install pear.phpunit.de/PHPUnit_Selenium-1.0.1
pear install phpunit/File_Iterator-1.2.3
pear install pear.phpunit.de/PHP_CodeCoverage-1.0.2
pear install pear.phpunit.de/PHPUnit-3.5.15

In fact, here's a full output of running this in a terminal on a CentOS 5.10 box

[root@mydev ~]# pear channel-discover components.ez.no
Adding Channel "components.ez.no" succeeded
Discovery of channel "components.ez.no" succeeded
[root@mydev ~]# pear channel-discover pear.symfony-project.com
Adding Channel "pear.symfony-project.com" succeeded
Discovery of channel "pear.symfony-project.com" succeeded
[root@mydev ~]# pear install --alldeps pear.phpunit.de/DbUnit-1.0.3
downloading DbUnit-1.0.3.tgz ...
Starting to download DbUnit-1.0.3.tgz (39,292 bytes)
..........done: 39,292 bytes
downloading YAML-1.0.6.tgz ...
Starting to download YAML-1.0.6.tgz (10,010 bytes)
...done: 10,010 bytes
install ok: channel://pear.symfony-project.com/YAML-1.0.6
install ok: channel://pear.phpunit.de/DbUnit-1.0.3
[root@mydev ~]# pear install phpunit/PHPUnit_TokenStream-1.1.5
No releases available for package "pear.phpunit.de/PHPUnit_TokenStream"
install failed
[root@mydev ~]# pear install pear.phpunit.de/PHPUnit_Selenium-1.0.1
downloading PHPUnit_Selenium-1.0.1.tgz ...
Starting to download PHPUnit_Selenium-1.0.1.tgz (15,285 bytes)
.....done: 15,285 bytes
install ok: channel://pear.phpunit.de/PHPUnit_Selenium-1.0.1
[root@mydev ~]# pear install phpunit/File_Iterator-1.2.3
downloading File_Iterator-1.2.3.tgz ...
Starting to download File_Iterator-1.2.3.tgz (3,406 bytes)
....done: 3,406 bytes
install ok: channel://pear.phpunit.de/File_Iterator-1.2.3
[root@mydev ~]# pear install pear.phpunit.de/PHP_CodeCoverage-1.0.2
downloading PHP_CodeCoverage-1.0.2.tgz ...
Starting to download PHP_CodeCoverage-1.0.2.tgz (109,280 bytes)
.........................done: 109,280 bytes
downloading ConsoleTools-1.6.1.tgz ...
Starting to download ConsoleTools-1.6.1.tgz (869,994 bytes)
...done: 869,994 bytes
downloading PHP_TokenStream-1.2.1.tgz ...
Starting to download PHP_TokenStream-1.2.1.tgz (9,854 bytes)
...done: 9,854 bytes
downloading Text_Template-1.1.4.tgz ...
Starting to download Text_Template-1.1.4.tgz (3,701 bytes)
...done: 3,701 bytes
downloading Base-1.8.tgz ...
Starting to download Base-1.8.tgz (236,357 bytes)
...done: 236,357 bytes
install ok: channel://pear.phpunit.de/PHP_TokenStream-1.2.1
install ok: channel://pear.phpunit.de/Text_Template-1.1.4
install ok: channel://components.ez.no/Base-1.8
install ok: channel://components.ez.no/ConsoleTools-1.6.1
install ok: channel://pear.phpunit.de/PHP_CodeCoverage-1.0.2
[root@mydev ~]# pear install pear.phpunit.de/PHPUnit-3.5.15
Did not download optional dependencies: pear/XML_RPC2, use --alldeps to download automatically
phpunit/PHPUnit can optionally use package "pear/XML_RPC2"
phpunit/PHPUnit can optionally use PHP extension "dbus"
downloading PHPUnit-3.5.15.tgz ...
Starting to download PHPUnit-3.5.15.tgz (118,859 bytes)
..........................done: 118,859 bytes
downloading PHP_Timer-1.0.5.tgz ...
Starting to download PHP_Timer-1.0.5.tgz (3,597 bytes)
...done: 3,597 bytes
downloading PHPUnit_MockObject-1.2.3.tgz ...
Starting to download PHPUnit_MockObject-1.2.3.tgz (20,390 bytes)
...done: 20,390 bytes
install ok: channel://pear.phpunit.de/PHP_Timer-1.0.5
install ok: channel://pear.phpunit.de/PHPUnit_MockObject-1.2.3
install ok: channel://pear.phpunit.de/PHPUnit-3.5.15
[root@mydev ~]# phpunit --version
PHPUnit 3.5.15 by Sebastian Bergmann.

And there was much rejoicing!

Nginx + FastCGI with the Quickness

CentOS 6.x (I've got 6.3 here) install. first off, you'll need both nginx and spawn-fcgi as well as php. For purposes of simplicity, I'll just go with the 5.3.3 that yum pulls in, but really any version (I ran it with php 5.4.8 for this example) will work. As long as it's compiled with the -cgi flags. and you have 'php-cgi' available as that's what spawn-fcgi executes.

yum install nginx spawn-fcgi php -y

This will install both of them with their default config's. You'll need to tweak a few things. First off, let's tackle /etc/sysconfig/spawn-fcgi

Spawn-fcgi Config

SOCKET=/var/run/php-fcgi.sock
OPTIONS="-u nginx -g nginx -s $SOCKET -S -M 0600 -C 8 -F 1 -P /var/run/spawn-fcgi.pid -- /usr/bin/php-cgi"

By default this ships with -C 32, which means it'll start 32 php-cgi processes. This seems like a lot in my experience. We have some very busy image servers and they do well with 4 to 8. I usually go with the "# cores + 2" idea and it's worked well for me so far. Any way, you'll also want to make sure you remember where that 'Socket' is defined. It doesn't really matter where it is, but it matters that you remember it!

Nginx Config

server {
  listen  80;
  server_name zabbix.example.com;
  root   /var/www/zabbix;
 
  location / {
   index  index.html index.htm index.php;
  }
 
  location ~ \.php$ {
   include /etc/nginx/fastcgi.conf;
   fastcgi_pass unix:/var/run/php-fcgi.sock;
   fastcgi_index index.php;
  }
 }

This server block will go in either your main nginx.conf file (/etc/nginx/nginx.conf on CentOS), or in a file included from that one. This will define a vhost listening on that "server_name", hosted in that "root". It will use the info in /etc/nginx/fastcgi.conf and pass that info over to your socket defined above (I told you to remember that!). Basically, the second location block tells nginx that any file ending with .php should use the fast-cgi and php socket to run. ... and that's it! I highly recommend trolling through the php.ini options as well as any other options in nginx to make sure there aren't any red-flags flying (I know I've tweaked a lot outside of this) but this should get you serving php!