Wiktionary.org: Helotism (zoology): A form of mutualism in which one species is forced to perform tasks for another, for their mutual benefit.
## This talk
Fast-forward through an installation
Connect to an elasticsearch cluster
## about me
business administration guy
20 years of Linux enthusiasm
Currently working as a Backlevel Software Support Engineer for a retail solution
/me 💞 complexity!
https://github.com/cprior
## Helotism ##
https://github.com/helotism/helotism
Installer script for a 250€-cluster solving basic sysadmin requirements
Bill of Materials
## Bootstrap script ##
## Basic config items ##
| variable name | getopts parameter |
|---------------|------------|
| __GITREMOTEORIGINURL | -r |
| __GITREMOTEORIGINBRANCH | -g |
| __COUNT | -c |
| __MASTERHOSTNAME | -m |
| __HOSTNAMEPREFIX | -n |
| __NETWORKSEGMENTCIDR | -s |
| __FQDNNAME | -d |
## Inner workings ##
| getopts | default |
|----------------|---------|
| -r | https://github.com/helotism/helotism.git |
| -g | master |
| -c | 2 |
| -m | axle |
| -n | spoke0 |
| -s | 10.16.6.1/24 |
| -d | wheel.example.com |
| -b | /dev/null |
##Powersupply
- prevent brown-out
- one switch for all boards
##Power Consumption
Rule of thumb:
- 1 Pi idle == 2.5W (5V * 0,5 A)
- 1 Pi under load, no USB == 5W (5V * 1 A)
Caveat: GPIO-pins are no USB ports ;)
- 5V passed straight through from USB
- 3.3V rail max 50mA
- GPIO pins 16ma in total
##On-Off-Switch
- hardware
- code
[raspberry-pi-geek.com On-Off-Switch](http://www.raspberry-pi-geek.com/Archive/2013/01/Adding-an-On-Off-switch-to-your-Raspberry-Pi "Adding an On/Off switch to your Raspberry Pi")
##Noise
##Discretization
##Debouncing
##Python logic…
```Python
def handleInterrupt(args):
button20.pressed = True #that's a fact, but...
button20.pressed_debounced = False
interrupted_at = datetime.datetime.now()
debounce_until = interrupted_at + datetime.timedelta(0,3)
while True:
if (datetime.datetime.now() > debounce_until):
journal.send('GPIO20 pressed DEBOUNCED.', FIELD2='GPIO20')
//do something
button20.pressed_debounced = True
return
else:
journal.send('GPIO20 pressed, not debounced', FIELD2='GPIO20')
time.sleep(0.5) #inside this interrupt handler only
```
##…and systemd daemonization.
```INI
[Unit]
Description=An GPIO interrupt listener
After=local-fs.target
[Service]
Type=simple
ExecStart=/bin/bash -c 'cd /opt/helotism/powersupply-env; \
source bin/activate; \
python ./mraa_interrupt.py'
[Install]
WantedBy=multi-user.target
```
##SaltStack Ecosystem
##SaltStack top file
```YAML
base: # environment
'web*': # targeted minions
- apache # state file 'apache.sls'
```
- the top.sls is a special state file as "entry point" into the fileserver
- "apache" references ```./apache.sls``` file
##SaltStack state file
```YAML
#apache.sls
{% if grains['os'] == 'Debian' %}
apache: apache2
{% elif grains['os'] == 'RedHat' %}
apache: httpd
{% endif %}
```
- Jinja2 template language
- one should read the fine manual: http://jinja.pocoo.org/docs/dev/
##SaltStack environments
```YAML
file_roots:
dev:
- /srv/salt/dev
base:
- /srv/salt
```
- environments are configured in the master config file
##SaltStack fileserver
```YAML
fileserver_backend: #first filename match wins
- roots
- git
gitfs_remotes:
- git://github.com/example/first.git
- https://github.com/example/second.git
- root: salt #subdirectory
- mountpoint: salt://sub/dir
- base: myTag05 #git branch
- file:///root/third
#top_file_merging_strategy: merge #same
#env_order: ['base', 'dev', 'prod']
```
- these are powerful configuration mechanisms: "infrastructure as code" served from a Git repo
- many ways to segment or override
##Sample Salt Usage
```bash
#remote execution?
salt '*' cmd.run 'uname -a'
```
```bash
#listing and accepting keys
salt-key -L
salt-key -A
```
```bash
#salt.modules.test.ping
salt '*' test.ping
```
```bash
#targeting by grains
salt -G 'os:(RedHat|Debian)' test.ping
```
```bash
#more sound than test.ping
salt-run manage.up
```
```bash
#apply common.sls on all (accepted) minions
salt '*' state.sls common
#This is the "endgame" in salt
salt '*' state.highstate
#remote execution!
salt '*' cmd.run 'uname -a'
```
##Demo
…
##Questions?
Fork it on GitHub!
Issues welcome.