About this blog

My first post on my new blog. This posts is about the blog itself and how it’s made.

I created this blog to write about DevOp’s things that keep me occupied. These will mainly be solutions to problems for which I had to search and try around for a long time. With this I want to achieve that others do not have to search so long for the right solution. Maybe, if I find time and motivation, I will also write articles about my work on MediathekView. And maybe I will also write articles about frameworks & technologies I am currently busy oneself with. And maybe I write articles about frameworks and technologies I’m currently working with.

The blog itself is made with Jekyll and AsciiDoc. It’s hosted on GitHub where you can also find the source. Because this don’t allow to send E-Mails on server side, I created an AWS Lambda for the contact form.

This is the source of my contact form lambda:

lambda_function.py view raw

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from __future__ import print_function
from botocore.exceptions import ClientError
from urllib.request import urlopen
import boto3
import json
import requests

def lambda_handler(event, context):
    if "g-recaptcha-response" in event and "mail" in event and "text" in event:
        success = checkRecaptcha(event["g-recaptcha-response"])
    else:
        success = False

    if success:
        send_email(event["mail"],event["text"])
    else:
        print("RECaptcha failed!")

    return {
        "location": event["referer"]
    }

def checkRecaptcha(captchaCode):
    requestData = { "secret": "mySecret", "response": captchaCode }
    data = requests.post("https://www.google.com/recaptcha/api/siteverify", data=requestData)
    result = data.json()
    return result.get('success', None)

def send_email(userMail, content):
    # Replace sender@example.com with your "From" address.
    # This address must be verified with Amazon SES.
    SENDER = "My Sender <cloud@my.domain>"

    # Replace recipient@example.com with a "To" address. If your account
    # is still in the sandbox, this address must be verified.
    RECIPIENT = "recipient@my.domain"

    # If necessary, replace us-west-2 with the AWS Region you're using for Amazon SES.
    AWS_REGION = "eu-west-1"

    # The subject line for the email.
    SUBJECT = "A user has sent you a message"

    # The character encoding for the email.
    CHARSET = "UTF-8"

    # Create a new SES resource and specify a region.
    client = boto3.client('ses',region_name=AWS_REGION)

    # Try to send the email.
    try:
        #Provide the contents of the email.
        response = client.send_email(
            Destination={
                'ToAddresses': [
                    RECIPIENT
                ]
            },
            ReplyToAddresses=[
                userMail,
            ],
            Message={
                'Body': {
                    'Text': {
                        'Charset': CHARSET,
                        'Data': content,
                    },
                },
                'Subject': {
                    'Charset': CHARSET,
                    'Data': SUBJECT,
                },
            },
            Source=SENDER,
        )
    # Display an error if something goes wrong.
    except ClientError as e:
        print(e.response['Error']['Message'])
    else:
        print("Email sent! Message ID:"),
        print(response['MessageId'])

Because the HTML form sends it’s data as www-form-urlencoded the following API gateway integration request mapping template is needed:

api_gateway_mapping_template.vtl view raw

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## convert HTML POST data or HTTP GET query string to JSON

## get the raw post data from the AWS built-in variable and give it a nicer name
#if ($context.httpMethod == "POST")
 #set($rawAPIData = $input.path("$"))
#elseif ($context.httpMethod == "GET")
 #set($rawAPIData = $input.params().querystring)
 #set($rawAPIData = $rawAPIData.toString())
 #set($rawAPIDataLength = $rawAPIData.length() - 1)
 #set($rawAPIData = $rawAPIData.substring(1, $rawAPIDataLength))
 #set($rawAPIData = $rawAPIData.replace(", ", "&"))
#else
 #set($rawAPIData = "")
#end

## first we get the number of "&" in the string, this tells us if there is more than one key value pair
#set($countAmpersands = $rawAPIData.length() - $rawAPIData.replace("&", "").length())

## if there are no "&" at all then we have only one key value pair.
## we append an ampersand to the string so that we can tokenise it the same way as multiple kv pairs.
## the "empty" kv pair to the right of the ampersand will be ignored anyway.
#if ($countAmpersands == 0)
 #set($rawPostData = $rawAPIData + "&")
#end

## now we tokenise using the ampersand(s)
#set($tokenisedAmpersand = $rawAPIData.split("&"))

## we set up a variable to hold the valid key value pairs
#set($tokenisedEquals = [])

## now we set up a loop to find the valid key value pairs, which must contain only one "="
#foreach( $kvPair in $tokenisedAmpersand )
 #set($countEquals = $kvPair.length() - $kvPair.replace("=", "").length())
 #if ($countEquals == 1)
  #set($kvTokenised = $kvPair.split("="))
  #if ($kvTokenised[0].length() > 0)
   ## we found a valid key value pair. add it to the list.
   #set($devNull = $tokenisedEquals.add($kvPair))
  #end
 #end
#end

## next we set up our loop inside the output structure "{" and "}"
{
  "referer" : "$input.params('referer')",
#foreach( $kvPair in $tokenisedEquals )
  ## finally we output the JSON for this pair and append a comma if this isn't the last pair
  #set($kvTokenised = $kvPair.split("="))
 "$util.urlDecode($kvTokenised[0])" : #if($kvTokenised[1].length() > 0)"$util.urlDecode($kvTokenised[1])"#{else}""#end#if( $foreach.hasNext ),#end
#end
}