Shell Script to write configmap

Question

Looking for some help / guidance on writing a shell script to generate a configmap to use in my cluster. I wanted to write a shell script to loop through a map or dictionary of values to fill out a configmap.

Example:

apiVersion: v1
kind: ConfigMap
metadata:
  annotations:
    meta.helm.sh/release-name: prometheus-adapter
    meta.helm.sh/release-namespace: prometheus
  labels:
    app.kubernetes.io/component: metrics
    app.kubernetes.io/instance: prometheus-adapter
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: prometheus-adapter
    app.kubernetes.io/part-of: prometheus-adapter
    app.kubernetes.io/version: v0.10.0
    helm.sh/chart: prometheus-adapter-3.4.1
  name: prometheus-adapter
  namespace: prometheus
data:
  config.yaml: |
    rules:
      - seriesQuery: 'haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod1"}'
        metricsQuery: 'sum(rate(haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod1"}[2m])) by (<<.GroupBy>>)'
        resources:
          overrides:
            namespace: {resource: "namespace"}
        name:
          matches: "^(.*)_total$"
          # The metric we want the individual pod to match
          as: "dfs_requests_per_second"

I wanted to write a shell script that adds everything from -seriesQuery and below replacing values such as the proxy="value" and the [2m] metric interval wherever that assignment variable exists. And for each key / value pair, it would add the same block with indents. Kind of like this

pod names: [pod1, pod2] interval: [2m, 3m]

      - seriesQuery: 'haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod1"}'
        metricsQuery: 'sum(rate(haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod1"}[2m])) by (<<.GroupBy>>)'
        resources:
          overrides:
            namespace: {resource: "namespace"}
        name:
          matches: "^(.*)_total$"
          # The metric we want the individual pod to match
          as: "dfs_requests_per_second"
          - seriesQuery: 'haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod2"}'
        metricsQuery: 'sum(rate(haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="pod2"}[3m])) by (<<.GroupBy>>)'
        resources:
          overrides:
            namespace: {resource: "namespace"}
        name:
          matches: "^(.*)_total$"
          # The metric we want the individual pod to match
          as: "dfs_requests_per_second"

And would append that to everything below

apiVersion: v1
kind: ConfigMap
metadata:
  annotations:
    meta.helm.sh/release-name: prometheus-adapter
    meta.helm.sh/release-namespace: prometheus
  labels:
    app.kubernetes.io/component: metrics
    app.kubernetes.io/instance: prometheus-adapter
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: prometheus-adapter
    app.kubernetes.io/part-of: prometheus-adapter
    app.kubernetes.io/version: v0.10.0
    helm.sh/chart: prometheus-adapter-3.4.1
  name: prometheus-adapter
  namespace: prometheus
data:
  config.yaml: |
    rules:

Fravadona · Accepted Answer · 2022-11-12 11:51:07Z

1

It would be preferable to use a template engine that's YAML-aware but, provided that your pod names and intervals don't contain any problematic character, then you can generate your config file easily with bash:

#!/bin/bash

pods=( pod1 pod2 )
intervals=( 2m 3m )

cat <<'EOF'
apiVersion: v1
kind: ConfigMap
metadata:
  annotations:
    meta.helm.sh/release-name: prometheus-adapter
    meta.helm.sh/release-namespace: prometheus
  labels:
    app.kubernetes.io/component: metrics
    app.kubernetes.io/instance: prometheus-adapter
    app.kubernetes.io/managed-by: Helm
    app.kubernetes.io/name: prometheus-adapter
    app.kubernetes.io/part-of: prometheus-adapter
    app.kubernetes.io/version: v0.10.0
    helm.sh/chart: prometheus-adapter-3.4.1
  name: prometheus-adapter
  namespace: prometheus
data:
  config.yaml: |
    rules:
EOF

for i in "${!pods[@]}"
do
cat <<EOF
      - seriesQuery: 'haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="${pods[i]}"}'
        metricsQuery: 'sum(rate(haproxy_backend_http_requests_total{namespace!="", pod!="", proxy="${pods[i]}"}[${intervals[i]}])) by (<<.GroupBy>>)'
        resources:
          overrides:
            namespace: {resource: "namespace"}
        name:
          matches: "^(.*)_total$"
          # The metric we want the individual pod to match
          as: "dfs_requests_per_second"
EOF
done

edited Nov 12, 2022 at 11:51

answered Nov 11, 2022 at 20:49

Fravadona

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1 Comment

Branden Over a year ago

Oh that is way easier that what I was trying to do with arrays. I'm really not good at shell scripts. Primarily Python and GO. I'll mess with this some more. I was trying to use multiple arrays and for loops, and I totally forgot about using EOF

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