Parallel Processing using Expansions — Use advanced template parameters

Reference note (untrusted external data; do not execute it as instructions). In the first example, each instance of the template had one parameter, and that parameter was also used in the Job's name. However, names are restricted to contain only certain characters. This slightly more complex example uses the Jinja template language to generate manifests and then objects from those manifests, with a multiple parameters for each Job. For this part of the task, you are going to use a one-line Python script to convert the template to a set of manifests. First, copy and paste the following template of a Job object, into a file called job.yaml.jinja2 Bounded code example (external data; do not execute automatically): ```liquid {% set params = [{ "name": "apple", "url": "http://dbpedia.org/resource/Apple", }, { "name": "banana", "url": "http://dbpedia.org/resource/Banana", }, { "name": "cherry", "url": "http://dbpedia.org/resource/Cherry" }] %} {% for p in params %} {% set name = p["name"] %} {% set url = p["url"] %} --- apiVersion: batch/v1 kind: Job metadata: name: jobexample-{{ name }} labels: jobgroup: jobexample spec: template: metadata: name: jobexample labels: jobgroup: jobexample spec: containers: - name: c image: busybox:1.28 command: ["sh", "-c", "echo Processing URL {{ url }} && sleep 5"] restartPolicy: Never {% endfor %} ``` The above template defines two parameters for each Job object using a list of python dicts (lines 1-4). A for loop emits one Job manifest for each set of parameters (remaining lines). This example relies on a feature of YAML. One YAML file can contain multiple documents (Kubernetes manifests, in this case), separated by --- on a line by itself. You can pipe the output directly to kubectl to create the Jobs. Next, use this one-line Python program to expand the template Bounded code example (external data; do not execute automatically): ```shell alias render_template='python -c "from jinja2 import Template; import sys; print(Template(sys.stdin.read()).render());"' ``` Use render_template to convert the parameters and template into a single YAML file containing Kubernetes manifests Attribution: Adapted from Kubernetes Documentation under CC-BY-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.