変数文字列が配列に格納されているbash変数のリストを設定解除したいと思います。

start.sh「ユーザーから渡された環境変数を取得したい」というスクリプトを呼び出すDockerfileを作成しています。docker-compose.ymlあるいは、docker run -e今やりたいことは、これらの変数のリストを配列に動的に定義することです。

## Environment Variables
## Missing Vars off the hop SLACK_HOOK_URL
CONFIG_SETTINGS=(
  AWS_ID
  AWS_SECRET
  BUCKET_REGION
  BUCKET_NAME
  DB_USER
  DB_PASSWORD
  DB_HOSTIP
  DB_PORT
  DB_NAME
)

この配列で定義された上記の変数のサブセットを単に設定解除しました。

CONFIG_SECRETS=(
  AWS_ID
  AWS_ID_STR
  AWS_SECRET
  AWS_SECRET_STR
  BUCKET_NAME
  BUCKET_NAME_STR
  DB_USER
  DB_USER_STR
  DB_PASSWORD
  DB_PASSWORD_STR
  DB_HOSTIP
  DB_HOSTIP_STR
  DB_PORT
  DB_PORT_STR
  DB_NAME
  DB_NAME_STR
)

私の問題は、次のforループにあります。

## Sanitization section
for i in "${!CONFIG_SECRETS[@]}"; do
  ## Nullify environment variables that contain secrets before launching.
  # echo ${CONFIG_SECRETS[$i]}
  eval $"${CONFIG_SECRETS[$i]}"=$""
  unset $"${CONFIG_SECRETS[$i]}"
  echo \$${CONFIG_SECRETS[$i]} is now to: $"${CONFIG_SECRETS[$i]}"
done

たとえば、以下はこれらの変数を繰り返し設定するために作成されたforループです。

for i in "${!CONFIG_SETTINGS[@]}"; do
  echo ${CONFIG_SETTINGS[$i]}"_KEY"
  ## Indirect references http://tldp.org/LDP/abs/html/ivr.html
  eval FROM_STRING=\$"${CONFIG_SETTINGS[$i]}_STR"
  eval VALUE_STRING=\$${CONFIG_SETTINGS[$i]}
  eval KEY_STRING=\$"${CONFIG_SETTINGS[$i]}_KEY"
  TO_STRING="$KEY_STRING$VALUE_STRING"
  sed -i '' "s/$FROM_STRING/$TO_STRING/g" ./config.tmpl
done

これにより、次の設定ファイルが変更されます。

{
  "aws_id": "YOUR-AWS-ID",
  "aws_secret": "YOUR-AWS-SECRET",
  "bucket_region": "YOUR-BUCKET-REGION",
  "bucket_name": "YOUR-BUCKET-NAME",
  "db_conn": "USER:PASSWORD@tcp(localhost:3306)/DBNAME",
  "slack_hook_url": ""
}

これは、この質問の範囲外のものを除く全体的なコンテキストスクリプトです。

#!/bin/bash

## Launch service will tell prism-bin what mode to run in.
LAUNCHMODE="${MODE:-$1}"

## This variable will be what can override default launch args.  I may modify this as I learn more about prism-bin
LAUNCHARGS="${CUSTOM_ARGS:-$2}"

## This is setup this way to handle any situations that might arise from the
## config being JSON and bash not being any good at JSON.
# ## Strings to replace.
AWS_ID_STR="YOUR-AWS-ID"
AWS_SECRET_STR="YOUR-AWS-SECRET"
BUCKET_REGION_STR="YOUR-BUCKET-REGION"
BUCKET_NAME_STR="YOUR-BUCKET-NAME"
DB_USER_STR="USER"
DB_PASSWORD_STR="PASSWORD"
DB_HOSTIP_STR="localhost"
DB_PORT_STR="3306"
DB_NAME_STR="DBNAME"

# Environment Variables/Defaults
## Json sucks in BASH/Shell so you need to add trailing commas intermittently.
## Just pay attention to this.  Also at some point I'll need to make a fringe
## case for handling key/values that aren't included in the default config.
AWS_ID="${AWS_ID:-potato}"
AWS_SECRET="${AWS_SECRET:-potato}"
BUCKET_REGION="${BUCKET_REGION:-potato}"
BUCKET_NAME="${BUCKET_NAME:-potato}"
DB_USER="${DB_USER:-potato}"
DB_PASSWORD="${DB_PASSWORD:-potato}"
DB_HOSTIP="${DB_HOSTIP:-potato}"
DB_PORT="${DB_PORT:-potato}"
DB_NAME="${DB_NAME:-potato}"

## Environment Variables in Array
CONFIG_SETTINGS=(
  AWS_ID
  AWS_SECRET
  BUCKET_REGION
  BUCKET_NAME
  DB_USER
  DB_PASSWORD
  DB_HOSTIP
  DB_PORT
  DB_NAME
)
CONFIG_SECRETS=(
  AWS_ID
  AWS_ID_STR
  AWS_SECRET
  AWS_SECRET_STR
  BUCKET_NAME
  BUCKET_NAME_STR
  DB_USER
  DB_USER_STR
  DB_PASSWORD
  DB_PASSWORD_STR
  DB_HOSTIP
  DB_HOSTIP_STR
  DB_PORT
  DB_PORT_STR
  DB_NAME
  DB_NAME_STR
)

## Sanitization section
# Awaiting someone smarter than me to suggest a method for this.
# https://unix.stackexchange.com/questions/474097/i-want-to-unset-a-list-of-bash-variables-that-have-their-variable-strings-stored
for i in "${CONFIG_SECRETS[@]}"; do
  unset $i
  eval echo \$"${CONFIG_SECRETS[$i]}"=\$${CONFIG_SETTINGS[$i]}
done