feat: Add scripts for publishing and consuming messages in SNS+SQS (off-ticket)

scripts/event-driven-architectures/README.md

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+# Scripts for testing event-driven architecture (SNS+SQS)
+
+## Purpose
+- Generating and publishing messages to a specified SNS topic, see `publish_messages.sh`.
+- Consuming messages that a subscribing SQS queue receives from an SNS topic, see `process_messages.sh`. 
+
+## How to use
+Within the `./scripts/event-driven-architectures` directory, define an `.env` file with the required environment variables. You can find out what variables are required by looking at the `check_env_variables` function calls within the scripts. For example, `check_env_variables "SNS_TOPIC" "TOTAL_NUMBER_OF_MESSAGES"` would require an `.env` file with the following (dummy values):
+
+```
+SNS_TOPIC="<sns-topic-arn>"
+TOTAL_NUMBER_OF_MESSAGES="<number-of-messages-to-publish>"
+```
+
+Login to AWS with:
+
+```
+aws sso login
+```
+
+Export the AWS profile of the account you want to run this script in (currently only `platform-sandbox` is supported):
+
+```
+export AWS_PROFILE=platform-sandbox
+```
+
+Run the selected script from within the `./scripts/event-driven-architectures` directory, e.g `publish_messages.sh`
+
+```
+bash publish_messages.sh
+```
+
+## Notes
+Remember to delete messages from the SQS queue once finished. This can be done with `process_messages.sh`.

scripts/event-driven-architectures/process_messages.sh

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+#!/usr/bin/env bash
+export AWS_PAGER=""
+
+if [[ ! -f .env ]]; then
+    echo ".env file not found, exiting script"
+    exit 1
+fi
+
+source .env
+
+source utils/check_aws_profile.sh
+check_aws_profile || exit 1
+
+source utils/check_env_variables.sh
+check_env_variables "SQS_QUEUE" || exit 1
+
+consume_message() {
+    local sqs_queue=$1
+
+    aws sqs receive-message \
+        --queue-url "$sqs_queue" \
+        --max-number-of-messages 1
+}
+
+delete_message () {
+    local sqs_queue=$1
+    local receipt_handle=$2
+    aws sqs delete-message --queue-url "$sqs_queue" --receipt-handle "$receipt_handle"
+}
+
+while true; do
+    echo "Consuming message"
+    response=$(consume_message "$SQS_QUEUE")
+    if [[ -z "$response" ]]; then
+        echo "No message received; polling again"
+        sleep 1
+        continue
+    fi
+
+    receipt_handle=$(
+        jq -r '.Messages[0].ReceiptHandle' <<< "$response"
+    )
+
+    message=$(
+        jq -r '
+            .Messages[0].Body as $body
+            | try ($body | fromjson) catch $body
+        ' <<< "$response"
+    )
+
+    echo "Processing message: $message"
+
+    echo "Deleting message with receipt handle: $receipt_handle"
+    delete_message "$SQS_QUEUE" "$receipt_handle"
+done

scripts/event-driven-architectures/publish_messages.sh

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+#!/usr/bin/env bash
+export AWS_PAGER=""
+
+if [[ ! -f .env ]]; then
+    echo ".env file not found, exiting script"
+    exit 1
+fi
+
+source .env
+
+source utils/check_aws_profile.sh
+check_aws_profile || exit 1
+
+source utils/check_env_variables.sh
+check_env_variables "SNS_TOPIC" "TOTAL_NUMBER_OF_MESSAGES" || exit 1
+
+mapfile -t messages < <(
+    for ((i=1; i<=TOTAL_NUMBER_OF_MESSAGES; i++)); do
+        echo "Message number: $i"
+    done
+)
+
+publish_message () {
+    local sns_topic=$1
+    local message=$2
+    aws sns publish --topic-arn "$sns_topic" --message "$message"
+}
+
+echo "Publishing messages"
+for message in "${messages[@]}"; do
+    publish_message "$SNS_TOPIC" "$message"
+done

scripts/event-driven-architectures/utils/check_aws_profile.sh

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+#!/usr/bin/env bash
+
+# TODO: update to handle multiple profiles
+check_aws_profile () {
+    if [[ "$AWS_PROFILE" != "platform-sandbox" ]]; then
+        echo "The currently selected AWS_PROFILE ('$AWS_PROFILE') is not permitted; set AWS_PROFILE to 'platform-sandbox' to run this script"
+        return 1
+    fi
+}

scripts/event-driven-architectures/utils/check_env_variables.sh

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+#!/usr/bin/env bash
+
+check_env_variables () {
+    local missing_variables=()
+    local env_var
+
+    for env_var in "$@"; do
+        [[ -n "${!env_var:-}" ]] || missing_variables+=("$env_var")
+    done
+
+    if [[ ${#missing_variables[@]} -gt 0 ]]; then
+        echo "The following variables must be set in .env:"
+        printf ' - %s\n' "${missing_variables[@]}"
+        return 1
+    fi
+}