Salt: Jinja variable containing an empty string leads to a None value

[tomlaredo]

Description of Issue/Question

Setup

From 2018.3.2 (or maybe a little before, didn't test), salt is treating an empty string in a jinja variable as a None value.

Steps to Reproduce Issue

jinjaerror.sls

{% set empty_str = "" %}
{% set str = "mystr" %}

myfile-state-context:
    file.managed:
        - name: /tmp/test.txt
        - template: jinja
        - source: salt://jinjaerror.cfg
        - context:
            empty_str: {{ empty_str }}
            empty_str2: {{ empty_str }}-test
            empty_str3: {{ empty_str }}""
            empty_str4: ""
            empty_str5: ''
            str: {{ str }}

myfile-state-contents:
    file.managed:
        - name: /tmp/test2.txt
        - contents: |
            empty_str  = {{ empty_str }}
            empty_str2 = {{ empty_str }}-test
            empty_str3 = {{ empty_str }}""
            empty_str4 = ""
            empty_str5 = ''
            str        = {{ str }}

jinjaerror.cfg

empty_str   = {{ empty_str }}
empty_str2  = {{ empty_str2 }}
empty_str3  = {{ empty_str3 }}
empty_str4  = {{ empty_str4 }}
empty_str5  = {{ empty_str5 }}
str         = {{ str }}

Execution :

local:
----------
          ID: myfile-state-context
    Function: file.managed
        Name: /tmp/test.txt
      Result: True
     Comment: File /tmp/test.txt updated
     Started: 12:06:11.664085
    Duration: 164.305 ms
     Changes:   
              ----------
              diff:
                  --- 
                  +++ 
                  @@ -0,0 +1,6 @@
                  +empty_str   = None
                  +empty_str2  = -test
                  +empty_str3  = 
                  +empty_str4  = 
                  +empty_str5  = 
                  +str         = mystr
----------
          ID: myfile-state-contents
    Function: file.managed
        Name: /tmp/test2.txt
      Result: True
     Comment: File /tmp/test2.txt updated
     Started: 12:06:11.828707
    Duration: 31.816 ms
     Changes:   
              ----------
              diff:
                  --- 
                  +++ 
                  @@ -0,0 +1,6 @@
                  +empty_str  = 
                  +empty_str2 = -test
                  +empty_str3 = ""
                  +empty_str4 = ""
                  +empty_str5 = ''
                  +str        = mystr

Summary for local
------------
Succeeded: 2 (changed=2)
Failed:    0
------------
Total states run:     2
Total run time: 196.121 ms

Versions Report

Salt Version:
           Salt: 2018.3.2

Dependency Versions:
           cffi: Not Installed
       cherrypy: 3.5.0
       dateutil: 2.5.3
      docker-py: Not Installed
          gitdb: Not Installed
      gitpython: Not Installed
          ioflo: Not Installed
         Jinja2: 2.9.4
        libgit2: Not Installed
        libnacl: Not Installed
       M2Crypto: 0.24.0
           Mako: Not Installed
   msgpack-pure: Not Installed
 msgpack-python: 0.4.8
   mysql-python: Not Installed
      pycparser: Not Installed
       pycrypto: 2.6.1
   pycryptodome: Not Installed
         pygit2: Not Installed
         Python: 2.7.13 (default, Nov 24 2017, 17:33:09)
   python-gnupg: Not Installed
         PyYAML: 3.12
          PyZMQ: 16.0.2
           RAET: Not Installed
          smmap: Not Installed
        timelib: Not Installed
        Tornado: 4.4.3
            ZMQ: 4.2.1

System Versions:
           dist: debian 9.4 
         locale: UTF-8
        machine: x86_64
        release: 4.13.16-2-pve
         system: Linux
        version: debian 9.4 

[Ch3LL]

looks like i'm able to replicate this and in older versions of salt.

ping @saltstack/team-core any ideas here? Is this just a part of jinja we would need to work around?

[gtmanfred]

this is how yaml works.

so, empty_str, even though you assigned "", it is actually nothing, so when you dump it out, you end up with this.

        - context:
            empty_str: 
            empty_str2: -test
            empty_str3: ""
            empty_str4: ""
            empty_str5: ''
            str: {{ str }}

And pyyaml interprets nothing being assigned to it as None, so this is the expected behavior.

If you want it to be an empty string, assign the variable a string of an empty string.

{% set empty_str = "''" %}

and that should dump out '' when the jinja is rendered.

[terminalmage]

You could also just do something like:

- context:
    foo: "{{ somevar }}"

The jinja still gets processed before the YAML, so the result would be an empty quoted string.

[tomlaredo]

Closing this issue as this is th expected behaviour and workaround propositions worked fine.