Question

Given this single-line string:

PG_USER=postgres PG_PORT=1234 PG_PASS=icontain=and*symbols

What would be the right way to assign each value to its designated variable so that I can use it afterward?

Context

I'm parsing the context of a k8s secret within a CronJob so that I can periodically call a Stored Procedure in our Postgres database.

To do so, I plan on using:

PG_OUTPUT_VALUE=$(PGPASSWORD=$PG_PASSWD psql -qtAX -h $PG_HOST -p $PG_PORT -U $PG_USER -d $PG_DATABASE -c $PG_TR_CLEANUP_QUERY)

echo $PG_OUTPUT_VALUE

The actual entire helm chart I'm currently trying to fix looks like this:

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: {{ template "fullname" $ }}-tr-cleanup-cronjob
spec:
  concurrencyPolicy: Forbid
  schedule: "* * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          volumes:
          - name: postgres
            secret:
              secretName: {{ template "fullname" $ }}-postgres
          containers:
          - name: {{ template "fullname" $ }}-tr-cleanup-pod
            image: postgres:12-alpine
            imagePullPolicy: Always
            env:
              - name: PG_PROPS
                valueFrom:
                  secretKeyRef:
                    name: {{ template "fullname" $ }}-postgres
                    key: postgres.properties
            command:
              - /bin/sh
              - -c
              - echo "props:" && echo $PG_PROPS && PG_USER=$(grep "^PG_USER=" | cut -d"=" -f2-) && echo $PG_USER && PG_TR_CLEANUP_QUERY="SELECT something FROM public.somewhere;" && echo $PG_TR_CLEANUP_QUERY && PG_OUTPUT_VALUE=$(PGPASSWORD=$PG_PASSWD psql -qtAX -h $PG_HOST -p $PG_PORT -U $PG_USER -d $PG_DATABASE -c $PG_TR_CLEANUP_QUERY) && echo PG_OUTPUT_VALUE
            volumeMounts:
              - name: postgres
                mountPath: /etc/secrets/postgres

Current approach

As you can see, I'm currently using:

PG_USER=$(grep "^PG_USER=" | cut -d"=" -f2-)

That is because I initially thought the secret would be output on multiple lines, but it turns out that I was wrong. The echo $PG_USER displays an empty string.

CodePudding user response：

This function can be reused to assign each variable individually:

extract() {
  echo "$INPUT" | grep -o "$1=.*" | cut -d" " -f1 | cut -d"=" -f2- ;
}

And to use it:

PG_USER=$(extract PG_USER)
PG_PORT=$(extract PG_PORT)
PG_PASS=$(extract PG_PASS)

Another potential solution, with a security concern, is to simply use:

eval "$INPUT"

It should only be used if you have validated the input.

CodePudding user response：

The bash declare command is appropriate here, and is safer than eval.

Suppose the input contains something potentially malicious

line='PG_USER=postgres PG_PORT=1234 PG_PASS=icontain=and*symbols`ls`'

I'm assuming none of the values contain whitespace. Let's split that string

read -ra assignments <<< "$line"

Now, declare each one

for assignment in "${assignments[@]}"; do declare "$assignment"; done

Everywhere we examine the input, we maintain double quotes.

Let's see what we ended up with:

$ declare -p PG_USER PG_PORT PG_PASS
declare -- PG_USER="postgres"
declare -- PG_PORT="1234"
declare -- PG_PASS="icontain=and*symbols\`ls\`"