create.sh

#!/bin/bash

# Documentation that helped with this:
#   https://github.com/luebken/serverless-the-manual-way
# Status:
#   https://eu-west-1.console.aws.amazon.com/lambda/home?region=eu-west-1

# See: https://developer.twitter.com/en/apps/16043135
TWITTER_CONSUMER_KEY=secret
TWITTER_CONSUMER_SECRET=secret
TWITTER_ACCESS_TOKEN=secret
TWITTER_ACCESS_TOKEN_SECRET=secret
MAX_TWEET_AGE=120h
WHITELIST=123:456:789

go get -u github.com/ChimeraCoder/anaconda
go get -u github.com/aws/aws-lambda-go/lambda

AWS_ACCOUNT_NUMBER=$(aws --profile me sts get-caller-identity|jq -r .Account)

if ! aws --profile me iam get-role --role-name twitter-ephemeral \
        > /dev/null 2>&1; then
  echo "Creating twitter-ephemeral role."
  aws --profile me iam create-role \
      --role-name twitter-ephemeral \
      --assume-role-policy-document file://twitter-ephemeral.json
  aws --profile me iam attach-role-policy \
      --role-name twitter-ephemeral \
      --policy-arn \
        arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
fi

SCHED_RULE=$(aws --profile me events describe-rule \
                 --name twitter-ephemera 2> /dev/null | jq -r .Arn)
if [[ -z "$SCHED_RULE" ]]; then
  aws --profile me events put-rule --schedule-expression "cron(5 2,14 * * ? *)" --name twitter-ephemeral
  SCHED_RULE=$(aws --profile me events describe-rule \
                   --name twitter-ephemera 2> /dev/null | jq -r .Arn)
fi

GOOS=linux go build \
  && zip ephemeral.zip ephemeral \
  && rm ephemeral \
  && aws --profile me lambda create-function \
         --runtime go1.x \
         --timeout 90 \
         --role=arn:aws:iam::$AWS_ACCOUNT_NUMBER:role/twitter-ephemeral \
         --handler=ephemeral \
         --function-name ephemeral \
         --zip-file fileb://ephemeral.zip \
         --environment="Variables={TWITTER_CONSUMER_KEY=$TWITTER_CONSUMER_KEY,TWITTER_CONSUMER_SECRET=$TWITTER_CONSUMER_SECRET,TWITTER_ACCESS_TOKEN=$TWITTER_ACCESS_TOKEN,TWITTER_ACCESS_TOKEN_SECRET=$TWITTER_ACCESS_TOKEN_SECRET,MAX_TWEET_AGE=$MAX_TWEET_AGE,WHITELIST=$WHITELIST}" \
  && rm ephemeral.zip

aws --profile me lambda add-permission \
      --function-name ephemeral \
      --statement-id scheduled-twitter-ephemeral \
      --action 'lambda:InvokeFunction' \
      --principal events.amazonaws.com \
      --source-arn $SCHED_RULE

twitter-ephemeral.json

{
	"Version": "2012-10-17",
	"Statement": {
  		"Effect": "Allow",
  		"Principal": {
    		"Service": "lambda.amazonaws.com"
  		},
  		"Action": "sts:AssumeRole"
	}
}