What you need to know about the $ENVIRONMENT

When running production things we're pretty much inevitably dealing with the environment. It is pretty straightforward but has some quirks. Here are some of the lessons I have learned.

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Transcript

1. @gaqzi what you need to know about the $ENVIRONMENT Björn Andersson
2. @gaqzi Björn 
 code monkey, devops, and 
 loud mouth pythonista
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5. @gaqzi what is an environment variable?
6. @gaqzi how do you set one then?
7. @gaqzi how do you set one then?
8. @gaqzi how do you set one then? > name="Björn"
9. @gaqzi how do you set one then? > name="Björn" > echo Hello, $name # => Hello, Björn
10. @gaqzi how do you set one then? > name="Björn" > echo Hello, $name # => Hello, Björn > env | grep name # => <empty>
11. @gaqzi how do you set one then? > name="Björn" > echo Hello, $name # => Hello, Björn > env | grep name # => <empty> > export name
12. @gaqzi how do you set one then? > name="Björn" > echo Hello, $name # => Hello, Björn > env | grep name # => <empty> > export name > env | grep name # => name=Björn
13. @gaqzi > AWS_ACCESS_TOKEN=deadbeef \ rake aws:s3:create_bucket[rdrc] what does this do?
14. @gaqzi so it’s all safe then?
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19. @gaqzi so it’s all safe then?
20. @gaqzi so it’s all safe then? > sleep 1000 &
 [1] 18270
21. @gaqzi so it’s all safe then? > sleep 1000 &
 [1] 18270 > ps -E 18270
 PID TTY TIME CMD
 18270 ttys001 0:00.00 sleep 1000 PATH=/Users/ba/.rbenv/shims:/ Users/ba/.rbenv/bin:/Users/ba/.pyenv/shims:/Users/ba/Library/Haskell/ bin:/Users/ba/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/ bin:/usr/local/mysql/bin name=Björn [… snip …]
22. @gaqzi variables set by the system
23. @gaqzi variables set by the system
24. @gaqzi variables set by the system • When your shell is loaded as a login shell it’ll:
25. @gaqzi variables set by the system • When your shell is loaded as a login shell it’ll: • Load system level startup scripts (/etc/pro fi le.d/*.sh)
26. @gaqzi variables set by the system • When your shell is loaded as a login shell it’ll: • Load system level startup scripts (/etc/pro fi les (.bashrc, .zshrc, etc…)
27. @gaqzi how does rbenv, pyenv, and the like work?
28. @gaqzi how does rbenv, pyenv, and the like work? • It’s all about your $PATH
29. @gaqzi how does rbenv, pyenv, and the like work? • It’s all about your $PATH • Search paths separated by colons (/Users/ba/.rbenv/shims:/usr/ local/bin:/usr/bin:/bin)
30. @gaqzi how does rbenv, pyenv, and the like work? • It’s all about your $PATH • Search paths separated by colons (/Users/ba/.rbenv/shims:/usr/ local/bin:/usr/bin:/bin) • Whatever is fi rst (left to right) in your path gets picked
31. @gaqzi . ├── User s │ └── b a │ └── .rben v │ └── shim s │ └── rub y ├── bi n │ └── emac s └── us r ├── bi n │ └── n c └── loca l └── bi n ├── rub y └── vim ->/bin/emacs export PATH=/bin:/usr/bin:/usr/local/bin:/Users/ba/.rbenv/shims
32. @gaqzi . ├── User s │ └── b a │ └── .rben v │ └── shim s │ └── rub y ├── bi n │ └── emac s └── us r ├── bi n │ └── n c └── loca l └── bi n ├── rub y └── vim ->/bin/emacs export PATH=/bin:/usr/bin:/usr/local/bin:/Users/ba/.rbenv/shims
33. @gaqzi . ├── User s │ └── b a │ └── .rben v │ └── shim s │ └── rub y ├── bi n │ └── emac s └── us r ├── bi n │ └── n c └── loca l └── bi n ├── rub y └── vim ->/bin/emacs export PATH=/bin:/usr/bin:/usr/local/bin:/Users/ba/.rbenv/shims
34. @gaqzi debugging
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38. @gaqzi debugging
39. @gaqzi debugging • init scripts not running as login shell, default path (/bin:/sbin)
40. @gaqzi debugging • init scripts not running as login shell, default path (/bin:/sbin) • some programs don’t inherit environment even if it’s there for security (nginx)
41. @gaqzi debugging • init scripts not running as login shell, default path (/bin:/sbin) • some programs don’t inherit environment even if it’s there for security (nginx) • lots of wrapper scripts to set the environment (/etc/defaults or /etc/ syscon fi g scripts)
42. @gaqzi debugging wkhtmltopdf
43. @gaqzi debugging wkhtmltopdf • nginx + rails + passenger after upgrade to Ruby 2.1.3
44. @gaqzi debugging wkhtmltopdf • nginx + rails + passenger after upgrade to Ruby 2.1.3 • picked up system ruby which was 2.0.0 (/usr/bin/ruby)
45. @gaqzi debugging wkhtmltopdf • nginx + rails + passenger after upgrade to Ruby 2.1.3 • picked up system ruby which was 2.0.0 (/usr/bin/ruby) • set a $PATH in nginx (env PATH=/Users/ba/.rbenv/shims:/usr/…;)
46. @gaqzi debugging wkhtmltopdf • nginx + rails + passenger after upgrade to Ruby 2.1.3 • picked up system ruby which was 2.0.0 (/usr/bin/ruby) • set a $PATH in nginx (env PATH=/Users/ba/.rbenv/shims:/usr/…;) • after that whtmltopdf picked up a .ruby-version fi le from $HOME/.ruby-version, pointing to 2.0.0 as well 😓
47. @gaqzi debugging wkhtmltopdf • nginx + rails + passenger after upgrade to Ruby 2.1.3 • picked up system ruby which was 2.0.0 (/usr/bin/ruby) • set a $PATH in nginx (env PATH=/Users/ba/.rbenv/shims:/usr/…;) • after that whtmltopdf picked up a .ruby-version f i
48. @gaqzi debugging ASCII encoding
49. @gaqzi debugging ASCII encoding • python 3.4 can’t write UTF-8 encoded strings to STDOUT, 
 because STDOUT is for some reason in ASCII
50. @gaqzi debugging ASCII encoding • python 3.4 can’t write UTF-8 encoded strings to STDOUT, 

51. @gaqzi debugging ASCII encoding • python 3.4 can’t write UTF-8 encoded strings to STDOUT, 

52. @gaqzi debugging ASCII encoding • python 3.4 can’t write UTF-8 encoded strings to STDOUT, 

53. @gaqzi debugging RubyMine
54. @gaqzi debugging RubyMine • RubyMine is running and saying that /Users/ba/.rbenv/shims/ruby doesn’t have ruby
55. @gaqzi debugging RubyMine • RubyMine is running and saying that /Users/ba/.rbenv/shims/ruby doesn’t have ruby • echo $PATH shows “/usr/local/opt/rbenv/shims:…”
56. @gaqzi debugging RubyMine • RubyMine is running and saying that /Users/ba/.rbenv/shims/ruby doesn’t have ruby • echo $PATH shows “/usr/local/opt/rbenv/shims:…” • ~/.rbenv/ is basically empty, removed it and it worked
57. @gaqzi pulling together
58. @gaqzi pulling together
59. @gaqzi pulling together • check your $PATH so you know where you’re going
60. @gaqzi pulling together • check your $PATH so you know where you’re going • env, because a snapshot lasts
61. @gaqzi pulling together • check your $PATH so you know where you’re going • env, because a snapshot lasts • $LANG, $LC_*, $TZ, $PATH, and others can affect you various weird and interesting ways
62. @gaqzi pulling together • check your $PATH so you know where you’re going • env, because a snapshot lasts • $LANG, $LC_*, $TZ, $PATH, and others can affect you various weird and interesting ways • your basic unix skills pay off. learn the basics of how your computer work and your life will be easier
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65. @gaqzi thanks! bandersson@pivotal.io @gaqzi