I was a little bit surprised to discover that his piece of code fails with an IOError exception instead of defaulting to omitting the value.
#!/usr/bin/env ansible-playbook -i localhost,
---
- hosts: localhost
tasks:
- debug: msg="{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') | default(omit) }}"
How can I load a value without raising an exception?
Please note that the lookup module supports a default value parameter but this one is useless to me because it works only when it can open the file.
I need a default value that works even when the it fails to open the file.
As far as I know Jinja2 unfortunately doesn't support any try/catch mechanism.
So you either patch ini lookup plugin / file issue to Ansible team, or use this ugly workaround:
---
- hosts: localhost
gather_facts: no
tasks:
- debug: msg="{{ lookup('first_found', dict(files=['test-ini.conf'], skip=true)) | ternary(lookup('ini', 'foo section=DEFAULT file=test-ini.conf'), omit) }}"
In this example first_found lookup return file name if file exists or empty list otherwise. If file exists, ternary filter calls ini lookup, otherwise omit placeholder is returned.
In case people like me stumble upon this question in 2022,
Ansible now supports rescue blocks, which is similar to try-catch-finally in programming languages.
Examples can be found in the official documentation Error handling with blocks.
You can use block/rescue as follows:
- hosts: localhost
tasks:
- block:
- debug: msg="{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') }}"
rescue:
- debug: msg="omit"
You can also convert your input file with a from_yaml filter before using the default filter
- name: "load a yaml file or a default value"
set_fact:
myvar: "{{ lookup('file', 'myfile.yml', errors='ignore') | from_yaml | default(mydefaultObject, true) }}"
To avoid the error when the path doesn't exist, use a condition to check for the path before attempting the lookup:
---
- hosts: localhost
tasks:
- debug: msg="{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') }}"
when: missing-file.conf | exists
You can use this with set_fact as well, then omit the undefined var when using it if required:
- hosts: localhost
tasks:
- set_fact:
foo: "{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') }}"
when: missing-file.conf | exists
- debug:
var: foo # undefined
msg: "{{ foo | default(omit) }}" # omitted
Note that lookups and Jinja2 tests run on the controller. If you need to check the path on the host, use the stat and either slurp or fetch modules:
- stat:
file: missing-remote-file-with-text-i-want
register: file
- slurp:
src: missing-remote-file-with-text-i-want
register: slurp
when: file.stat.exists
- set_fact:
foo: "{{ slurp.content | b64decode }}"
when: file.stat.exists
- fetch:
src: missing-file.conf
dest: /tmp/fetched
fail_on_missing: False
- set_fact:
bar: "{{ lookup('ini', 'foo section=DEFAULT file=/tmp/fetched/' + inventory_hostname + '/missing-file.conf') }}"
when: ('/tmp/fetched/' + inventory_hostname + '/missing-file.conf') | exists
Second note, in Ansible v2.5 the grammar for using the path tests was changed, the format is now:
- set_fact:
foo: "{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') }}"
when: missing-file.conf is exists
Related
I am performing a grep with multiple items.
---
- hosts: my_host
gather_facts: false
vars:
my_list:
- whatever
- something
tasks:
- name: grep for item in search path
shell: "grep -rIL {{ item }} /tmp"
register: the_grep
loop: "{{ my_list }}"
- debug:
msg: "{{ item.stdout_lines }}"
loop: "{{ the_grep.results }}"
Depending on the result, multiple files could match.
msg:
- /tmp/something.conf
- /tmp/folder/file.txt
Q: How would I configure Ansible to loop over the items in stdout_lines?
The use case I'm solving is to delete .ini sections based on the item, but in this case, Ansible doesn't loop over the stdout_lines.
- name: remove stanza from ini file
ini_file:
path: "{{ item.stdout_lines }}"
section: "{{ item.item }}"
mode: '0600'
state: absent
loop: "{{ the_grep.results }}"
when: item.stdout_lines | length > 0
It seems that this doesn't work, but configuring item.stdout_lines[0] gives the partially expected result, since Ansible will use only the first item in that list. But ofc, not the 2nd and so on.
Perhaps there's a prettier answer, but solved it by using with_nested and creating a json_query:
- name: remove stanza from ini file
ini_file:
path: "{{ item.0 }}"
section: "{{ item.1.item }}"
mode: '0600'
state: absent
with_nested:
- "{{ the_grep | json_query('results[].stdout_lines[]') }}"
- "{{ the_grep.results }}"
I'm trying to set a var only when a file exists, here is one of my attempts
---
- hosts: all
tasks:
- stat:
path: '{{ srch_path_new }}/bin/run'
register: result
- vars: srch_path="{{ srch_path_new }}"
when: result.stat.exists
This also didn't work
- vars: srch_path:"{{ srch_path_new }}"
The task you are looking for is called set_fact: and is the mechanism ansible uses to declare arbitrary "host variables", sometimes called "hostvars", or (also confusingly) "facts"
The syntax would be:
- set_fact:
srch_path: "{{ srch_path_new }}"
when: result.stat.exists
Also, while vars: is a legal keyword on a Task, its syntax is the same as set_fact: (or the vars: on the playbook): a yaml dictionary, not a key:value pair as you had. For example:
- debug:
msg: hello, {{ friend }}
vars:
friend: Jane Doe
and be aware that vars: on a task exist only for that task
site.yaml
---
- name: someapp deployment playbook
hosts: localhost
connection: local
gather_facts: no
vars_files:
- secrets.yml
environment:
AWS_DEFAULT_REGION: "{{ lookup('env', 'AWS_DEFAULT_VERSION') | default('ca-central-1', true) }}"
tasks:
- include: tasks/create_stack.yml
- include: tasks/deploy_app.yml
create_stack.yml
---
- name: task to create/update stack
cloudformation:
stack_name: someapp
state: present
template: templates/stack.yml
template_format: yaml
template_parameters:
VpcId: "{{ vpc_id }}"
SubnetId: "{{ subnet_id }}"
KeyPair: "{{ ec2_keypair }}"
InstanceCount: "{{ instance_count | default(1) }}"
DbSubnets: "{{ db_subnets | join(',') }}"
DbAvailabilityZone: "{{ db_availability_zone }}"
DbUsername: "{{ db_username }}"
DbPassword: "{{ db_password }}"
tags:
Environment: test
register: cf_stack
- name: task to output stack output
debug: msg={{ cf_stack }}
when: debug is defined
Error at line debug: msg={{ cf_stack }} saying:
This module prints statements during execution and can be useful for debugging variables or expressions without necessarily halting the playbook. Useful for debugging together with the 'when:' directive.
This module is also supported for Windows targets.
Incorrect type. Expected "object".
Ansible documentation allows the above syntax, as shown here
$ ansible --version
ansible 2.5.1
....
How to resolve this error?
You still need to remember quotes for lines starting with a {, even when using short-hand notation:
- debug: msg="{{ cf_stack }}"
This would be more obvious using full YAML notation:
- debug:
msg: "{{ cf_stack }}"
Also, given this is a variable, you could just do:
- debug:
var: cf_stack
- name: Create Dirs for rs disk
file:
name: "{{ /rs{{ items }}"
state: directory
with_sequence: start=1 end={{ disk_group[inventory_hostname]['rs'] | length }}
when: disk_group[inventory_hostname]['rs'] is defined
tasks
When "when" clause is false, how to avoid errors that vairable is undefined in "with_sequence".
In fact, use ignore_errors can do that, but I do think it's not a good idea.
You might want to try this example of include_tasks
> cat task.yml
- debug: var=item
with_sequence: start=1 end={{ rs|length }}
> cat playbook.yml
- hosts: localhost
vars:
# rs: test
tasks:
- include_tasks: task.yml
when: rs is defined
Consider the following play. What I am trying to do is add a field, tmp_path which is basically the key and revision appended together to each element in the scripts dict.
---
- hosts: localhost
connection: local
gather_facts: no
vars:
scripts:
a.pl:
revision: 123
b.pl:
revision: 456
tasks:
- with_dict: "{{ scripts }}"
debug:
msg: "{{ item.key }}_{{ item.value.revision }}"
# - with_items: "{{ scripts }}"
# set_fact: {{item.value.tmp_path}}="{{item.key}}_{{item.value.revision}}"
# - with_items: "{{ scripts }}"
# debug:
# msg: "{{ item.value.tmp_path }}"
...
Obviously the commented code doesn't work, any idea how I can get this working? Is it possible to alter the scripts dict directly, or should I somehow be creating a new dict to reference instead?
By the way welcome to correct the terminology for what I am trying to do.
OK, I think I got a solution (below), at least to let me move forwards with this. Disadvantages are it has removed the structure of my dict and also seems a bit redundant having to redefine all the fields and use a new variable, If anyone can provide a better solution I will accept that instead.
---
- hosts: localhost
connection: local
gather_facts: no
vars:
scripts:
a.pl:
revision: 123
b.pl:
revision: 456
tasks:
- with_dict: "{{ scripts }}"
debug:
msg: "{{ item.key }}_{{ item.value.revision }}"
- with_dict: "{{ scripts }}"
set_fact:
new_scripts: "{{ (new_scripts | default([])) + [ {'name': item.key, 'revision': item.value.revision, 'tmp_path': item.key ~ '_' ~ item.value.revision}] }}"
# - debug:
# var: x
# - with_dict: "{{ scripts }}"
- with_items: "{{ new_scripts }}"
debug:
msg: "{{ item.tmp_path }}"
...
BTW credit to the following question which pointed me in the right direction:
Using Ansible set_fact to create a dictionary from register results