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authorChad Smith <chad.smith@canonical.com>2021-12-02 21:25:43 -0700
committerGitHub <noreply@github.com>2021-12-02 21:25:43 -0700
commit0fe96a44cde48cc688afe75beb8fd126c8892b8c (patch)
tree86c3b3e848c2e0bd234a675edc526a22834fcac6 /doc/rtd
parentff10fc0914a8b29acc23348d7848439a5eb4960a (diff)
downloadvyos-cloud-init-0fe96a44cde48cc688afe75beb8fd126c8892b8c.tar.gz
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jinja: provide and document jinja-safe key aliases in instance-data (SC-622) (#1123)
Allow #cloud-config and cloud-init query to use underscore-delimited "jinja-safe" key aliases for any instance-data.json keys containing jinja operator characters. This provides a means to use Jinja's dot-notation instead of square brackets and quoting to reference "unsafe" obtain attribute names. Support for these aliased keys is available to both #cloud-config user-data and `cloud-init query`. For example #cloud-config alias access can look like: {{ ds.config.user_network_config }} - instead of - {{ ds.config["user.network-config"] }}
Diffstat (limited to 'doc/rtd')
-rw-r--r--doc/rtd/topics/instancedata.rst16
1 files changed, 11 insertions, 5 deletions
diff --git a/doc/rtd/topics/instancedata.rst b/doc/rtd/topics/instancedata.rst
index 6c17139f..c33b907a 100644
--- a/doc/rtd/topics/instancedata.rst
+++ b/doc/rtd/topics/instancedata.rst
@@ -530,12 +530,18 @@ Both user-data scripts and **#cloud-config** data support jinja template
rendering.
When the first line of the provided user-data begins with,
**## template: jinja** cloud-init will use jinja to render that file.
-Any instance-data-sensitive.json variables are surfaced as dot-delimited
-jinja template variables because cloud-config modules are run as 'root'
-user.
+Any instance-data-sensitive.json variables are surfaced as jinja template
+variables because cloud-config modules are run as 'root' user.
-
-Below are some examples of providing these types of user-data:
+.. note::
+ cloud-init also provides jinja-safe key aliases for any instance-data.json
+ keys which contain jinja operator characters such as +, -, ., /, etc. Any
+ jinja operator will be replaced with underscores in the jinja-safe key
+ alias. This allows for cloud-init templates to use aliased variable
+ references which allow for jinja's dot-notation reference such as
+ ``{{ ds.v1_0.my_safe_key }}`` instead of ``{{ ds["v1.0"]["my/safe-key"] }}``.
+
+Below are some other examples of using jinja templates in user-data:
* Cloud config calling home with the ec2 public hostname and availability-zone