Replacing / by \ in a string with ansible - ansible

Question

I need to replace all the / by \ in a string stored in a variable.
I'm just trying to do it a simple as possible to test it with a debug, but no matter how I try it I dont get the expected result of just replacing character to character. I think it's probably just a single/double quote problem or maybe the \ needs to be escaped in a certain way I don't know.
vars:
- SecGroup: '/stuff/foo/thing'
tasks:
- name: Display modified var
debug:
msg: "{{ SecGroup | replace('/','\') }}"
Expected output : \stuff\foo\thing
Output with differents tries :
- name: Display modified var
debug:
msg: "{{ SecGroup | replace('/','\') }}"
TASK [Display modified var]
ok: [localhost] => {
"msg": "stufffoothing"
}
- name: Display modified var
debug:
msg: "{{ SecGroup | replace('/','\\') }}"
TASK [Display modified var]
fatal: [localhost]: FAILED! => {"msg": "Unexpected failure during module execution."}
- name: Display modified var
debug:
msg: "{{ SecGroup | replace('/','\\\') }}"
TASK [Display modified var]
fatal: [localhost]: FAILED! => {"msg": "Unexpected failure during module execution."}
- name: Display modified var
debug:
msg: "{{ SecGroup | replace('/','\\\\') }}"
TASK [Display modified var]
ok: [localhost] => {
"msg": "\\\\stuff\\\\foo\\\\thing"
}
I also tried to revert the quotes :
- name: Display modified var
debug:
msg: '{{ SecGroup | replace("/","\") }}'
TASK [Display modified var]
fatal: [localhost]: FAILED! => {"msg": "Unexpected failure during module execution."}
I can't explain the output of this one
- name: Display modified var
debug:
msg: '{{ SecGroup | replace("/","\\") }}'
TASK [Display modified var]
ok: [localhost] => {
"msg": "\\\\stuff\\\\foo\\\\thing"
}

Answer 1

I think you've stumbled upon an edge case that involves the interaction between YAML escaping and Python escaping. The only way I was able to get it to work was introducing a guard character -- something to ensure that the \ isn't the last character in the expression, which we then remove with a subsequent replace() filter. Here I'm using a semicolon (;), but you could use anything that you're certain won't be in your SecGroup string. Note that your choice of quotes is significant; quoting the entire string with single quotes inhibits YAML escaping:
- name: With guard character
debug:
msg: '{{ SecGroup | replace("/","\;") | replace(";", "") }}'
Outputs:
TASK [With guard character] *******************************************************************************************************************************************************************
ok: [localhost] => {
"msg": "\\stuff\\foo\\thing"
}
Which is exactly what you want (remembering that a single \ is encoded as \\ in JSON output).
Regarding this:
- name: Display modified var
debug:
msg: '{{ SecGroup | replace("/","\\") }}'
TASK [Display modified var]
ok: [localhost] => {
"msg": "\\\\stuff\\\\foo\\\\thing"
}
You are successfully replacing / with two backslashes, \\. Since a backslash must be encoded as \\ in JSON output, a double backslash will end up represented as \\\\, so this:
"msg": "\\\\stuff\\\\foo\\\\thing"
Means you actually have the string:
\\stuff\\foo\\thing

Answer 2

I wanted to add an alternative solution:
If you're familiar with Python, you can just write a custom filter module and avoid multiple layers of escaping. E.g., if you were to create filter_plugins/reslash.py with the following content:
#!/usr/bin/python
def filter_reslash(val):
return val.replace('/', '\\')
class FilterModule(object):
filter_map = {
'reslash': filter_reslash
}
def filters(self):
return self.filter_map
You could then write your playbook like this:
---
- hosts: localhost
gather_facts: false
vars:
- SecGroup: '/stuff/foo/thing'
tasks:
- debug:
msg: "{{ SecGroup | reslash }}"
That's arguably a cleaner solution.

Answer 3

The solution by #larsks didn't entirely work for me as described. I needed to escape the backslash with double slashes \ plus the guard character in order for it to work in the Ansible Playbook.
This works: replace('/','\\;') | replace(';', '')

Answer 4

Another easy solution is to leave escaping backslash to ansible itself. This is how i would have done.
- set_fact:
replacer: '\'
- name: With guard character
debug:
msg: '{{ SecGroup | replace("/",replacer)}}'

Answer 5

Same workaround if you want replace 1 backslash with double backslash on a windows path.
- hosts: localhost
gather_facts: False
vars:
- iis_manager_logdir: 'C:\inetpub\logs\manager-logs'
tasks:
- set_fact:
iis_mng_logs: "{{ iis_manager_logdir | regex_replace('\\\\', '\\\\;') | regex_replace(';', '\\\\') }}"
- name: Original path
debug:
msg: "{{ iis_manager_logdir }}"
- name: New path
debug:
msg: "{{ iis_mng_logs }}"

Answer 6

Thanks to the #larsks's answer i've managed to replace backslashes in ansible string variable value without intermediate replace. It's possible by supplying into regex_replace expression a regex quantifier {1} between last backslash and closing quote.
For example, expression like {{ install_path | regex_replace('\\\\{1}', '/') }} replaces all occurences of backslash \ to forward slash /. It was used to replace Windows path delimiters with Unix-like ones:
- name: install libs
win_shell: "pip install --no-index --find-links \"file://{{ install_path | regex_replace('\\\\{1}', '/') }}/libs\" attrs requests"
become: true

Answer 7

For what its worth, after countless struggles, this is what has worked for me without any workarounds:
Forward to Back Slash
ForwardtoBackSlash: "{{ 'c:/test' | regex_replace('\\\/', '\\\\') }}"
output:
c:\test
Single Slash to Double Slash
SingleSlashtoDoble: "{{ 'C:\test\logs\logfile.txt'| regex_replace('\\\\', '\\\\\\\\') }}"
Output:
C:\\test\\logs\\logfile.txt
I hope it helps someone.