Serverless static website - part 9

One of the greatest benefits of cloud computing is the ability to automate processes and up to this point, we've learned how to set everything up via AWS console web interface.

Why automate?

It is always good to know how to manage stuff via console in case we need to manually modify something, but we should aim to avoid this practice. Instead, limit the use of the console to a bare minimum and the rest of the time, aim for some automated way, this has the following advantages:

• We can keep source code / templates under source control, allowing to keep track of changes.
• It can be reused to replicate in case of a new customer / new environment / etc.
• No need to remember where every single option is located as the UI can change.
• It can be transferred to another account in a matter of a few minutes.

In AWS world, the automated process is achieved by creating templates in CloudFormation and deploying them to stacks.

I have already created a couple of CloudFormation templates to automate all the process described to this point, they can be found at my GitHub repo.

CloudFormation templates

In order to automate this infrastructure, I've divided resources into two separate templates: one containing the SSL certificate and the other containing all the rest of the resources. The reason why the SSL certificate is in another template is because it needs to be run on N. Virginia region (US-East-1) as explained earlier when we created it manually, it's a CloudFront requirement.

Templates can contain parameters that make them more flexible, in this case, there is a parameter that controls the creation of a redirection bucket, we might have a scenario when we want just a website on a sub domain and we might not want to redirect from the naked domain. These are the parameters:

SSL Certificate template

• DomainName: The site domain name (naked domain only)

Infrastructure template

• HostedZone: This is just for reference, it should not be changed
• SSLCertificate: This should be taken from the output of the SSL certificate template
• DomainName: Same as above, only naked domain
• SubDomainName: specific sub domain, typically www
• IncludeRedirectToSubDomain: Whether it should include a redirection bucket from the naked domain to the subdomain

Creating SSL certificate Stack

First, let's make sure we are in N. Virginia region. Go to CloudFormation console, once there, click Create Stack button. We are presented with Select Template screen, where we'll choose a template from my repository (ssl-certificate.yaml) by selecting Upload a template to Amazon S3 radio button.

Click Next, you'll see the input parameters page including the stack name which I'll name abelperez-info-ssl-stack to give it some meaningful name.

After entering the required information, click Next and Next again, then on Create button. You'll see the Create in progress status in the stack.

At this point, the SSL certificate is being created and will require the identity verification just like when it was created manually, this will block the stack creation until the validation process is finished, so go ahead and check your email and follow the link to validate the identity to proceed with the stack creation.

Once the creation is done you'll see the Create complete status in the stack, on the lower pane, select Outputs, you'll find SSLCertificateArn. Take that value and copy it somewhere temporarily, we'll need it for our next stack.

Creating Infrastructure Stack

Following a similar process, let's create the second stack containing most of the resources to provision. In this case we are not forced to create it in any specific region, we can choose any provided all the services are available, for this example I'll Ireland (EU-West-1). The template can be downloaded from my repository (infrastructure.yaml).

This time, you are presented a different set of parameters, SSL Certificate will be the output of the previous stack as explained above. Domain name will be exactly the same as in the previous stack, give we are using the SSL certificate for this domain. Subdomain will be www and I'll include a redirection as I expect users to be redirected from abelperez.info to www.abelperez.info. I'll name the stack abelperez-info-infra-stack just to make it meaningful.

Since this template will create IAM users, roles and policies, we need to acknowledge this by ticking the box.

Once we hit Create, we can see the Create in progress screen.

This process can take up to 30 minutes, so please be patient, this takes so long time to create the stack because we are provisioning CloudFront distributions and they can take some time to propagate.

Once the stack is created, we can take note of a couple of values from the output: CodeCommit repository url (either SSH or HTTPS) and the Static bucket name.

Manual steps to finish the set up.

With all resource automatically provisioned by the templates, we are in a position where the only thing we need is to link our local SSH key with the IAM user. To do that, let's do exactly what we did when it was set up manually in part 6.

In my case, I chose to use SSH key, so I went to IAM console, found the user, under Security Credentials, I uploaded my SSH public key.

We also need to update the buildspec.yml to run our build, can be downloaded from the above linked GitHub repository. The placeholder <INSERT-YOUR-BUCKET-NAME-HERE> must be replaced with the actual bucket name, in this instance the bucket name generated is abelperez-info-infra-stack-staticsitebucket-1ur0k115f2757 and my buildspec.yml looks like:

version: 0.2

phases:
  build:
    commands:
      - mkdir dist
      - cp *.html dist/

  post_build:
    commands:
      - aws s3 sync ./dist 
        s3://abelperez-info-infra-stack-staticsitebucket-1ur0k115f2757/ 
        --delete --acl=public-read

Let's test it!

Our test consist of cloning the git repository from CodeCommit, add two files: index.html and buildspec.yml. Then we'll perform a git push and we expect it will trigger the build executing the s3 sync command and copying the index.html to our destination bucket which will be behind CloudFront and CNamed by Route 53. In the end, we should be able to just browse www.abelperez.info and get whatever the result is in index.html just uploaded.

Just a note, if you get a HTTP 403 instead of the expected HTML, then just wait for a few minutes, CloudFront/Route 53 might not be fully propagated just yet.

abel@ABEL-DESKTOP:~$ git clone ssh://git-codecommit.eu-west-1.amazonaws.com/v1/repos/www.abelperez.info-web
Cloning into 'www.abelperez.info-web'...
warning: You appear to have cloned an empty repository.
abel@ABEL-DESKTOP:~$ cd www.abelperez.info-web/
abel@ABEL-DESKTOP:~/www.abelperez.info-web$ git add buildspec.yml index.html 
abel@ABEL-DESKTOP:~/www.abelperez.info-web$ git commit -m "initial commit"
[master (root-commit) dc40888] initial commit
 Committer: Abel Perez Martinez 
Your name and email address were configured automatically based
on your username and hostname. Please check that they are accurate.
You can suppress this message by setting them explicitly. Run the
following command and follow the instructions in your editor to edit
your configuration file:

    git config --global --edit

After doing this, you may fix the identity used for this commit with:

    git commit --amend --reset-author

 2 files changed, 16 insertions(+)
 create mode 100644 buildspec.yml
 create mode 100644 index.html
abel@ABEL-DESKTOP:~/www.abelperez.info-web$ git push
Counting objects: 4, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), 480 bytes | 0 bytes/s, done.
Total 4 (delta 0), reused 0 (delta 0)
To ssh://git-codecommit.eu-west-1.amazonaws.com/v1/repos/www.abelperez.info-web
 * [new branch]      master -> master
abel@ABEL-DESKTOP:~/www.abelperez.info-web$ curl https://www.abelperez.info
<html>
<body>
<h1>Hello from S3 bucket :) </h1>
</body>
</html>

Serverless static website - part 8

All the way to this point, we have created the resources that allow us to store our source code and deploy it to S3 bucket. However, this build/deploy process has to be triggered manually by going to the console, finding the CodeBuild project and clicking Start build button.

This doesn't sound good enough for a complete development cycle. We need something that links changes in CodeCommit repository and CodeBuild project together so the build process is triggered automatically when changes are pushed to git. That magic link is called CloudWatch

Amazon CloudWatch is a monitoring service for AWS cloud resources and applications you run on AWS. Amongst other things it allows to create event rules that watch service events and trigger actions on target services. In this case we are going to watch changes in CodeCommit repository and link that to the Start build action on CodeBuild.

Creating the Rule

First, we need to go to CloudWatch console, to get there, select Services from the top menu, then under Management Tools, select CloudWatch. Once there, select Rules from the left hand side menu, under Events category.

Configure the Event source

We'll see two panes, the left hand side is for the event source, the right one is to choose the target of our rule.

On the left side, select Event Pattern radio button option (default one), next from the drop down menu, select Events by Service. For Service Name, find the option corresponding to CodeCommit and Event Type CodeCommit Repository State Change.

Since we are only interested in the changes of the repository we previously created, select Specific resource(s) by ARN radio button option. Then, enter the ARN of the corresponding CodeCommit repository, which can be found by going to Settings in CodeCommit console. It should be something like arn:aws:codecommit:eu-west-1:111111111111:abelperez.info-web.

Configure the Target

On the right side, click Add Target, then from the drop down menu, select CodeBuild project. A new form is displayed where we need to enter the project ARN, this is a bit tricky because for some reason, CodeBuild console doesn't show this information. Head to ARN namespaces documentation page and find CodeBuild, the format will be something like arn:aws:codebuild:us-east-1:111111111111:project/abelperez.info-builder.

Next step is to define the role, which in this case, we'll leave as it is proposed to Create a new role for this specific resource, AWS will figure out what permissions based on the type of resource we set as target, this might not be entirely accurate in the case of Lambda as target, we'd need to edit the role and add some policy for specific access.

We skipped Configure input on purpose as no input is required to trigger the build, so no need to change that setting.

Finish the process

Click on Configure details to go to step 2 where the process will finish.

Enter name and optionally a description, leave State as Enabled so it will be active from the moment we create it. Click on Create rule finish the process.

Let's test it

How can we know if the rule is working as expected? Since we connected changes on CodeCommit repository with starting a build on CodeBuild, let's do some changes to our repository, for example, adding a new file index3.html

abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git add index3.html 
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git commit -m "3rd file"
[master e953674] 3rd file
 1 file changed, 1 insertion(+)
 create mode 100644 index3.html
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git push
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (2/2), done.
Writing objects: 100% (3/3), 328 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
To ssh://git-codecommit.eu-west-1.amazonaws.com/v1/repos/abelperez.info-web
   27967c1..e953674  master -> master

Now let's check CodeBuild console to see the build being triggered by the rule we've created

As expected, the build ran without any human intervention, which was the goal of the CloudWatch Event rule. Since the build succeeded, we can also check the existence of the new file in the bucket.

abel@ABEL-DESKTOP:~/Downloads$ aws s3 ls s3://www.abelperez.info
2018-02-21 23:19:53         18 index.html
2018-02-21 23:19:53         49 index2.html
2018-02-21 23:19:53         49 index3.html

Serverless static website - part 7

Now that we have our source code versioned and safely stored, we need a way to make it go to our S3 bucket, otherwise it won't be visible to the public. There are, as usual, many ways to address this scenario, but as a developer, I can't live without CI/CD integration for all my processes. In this case, we have a very simple process, and we can combine the building and deploying steps in one go. To do that, once again, AWS offers some useful services, I'll be using CodeBuild for this task.

Creating the access policy

Just like anything in AWS, a CodeBuild project needs access to other AWS services and resources. The way this is done is by applying service roles with policies. As per AWS docs, a CodeBuild project needs the following permissions:

• logs:CreateLogGroup
• logs:CreateLogStream
• logs:PutLogEvents
• codecommit:GitPull
• s3:GetObject
• s3:GetObjectVersion
• s3:PutObject

The difference is that the proposed policy in the docs does not restrict access to any resource, it suggests to change the * to something more specific. The following is the resulting policy restricting access to logs in the log group created by the CodeBuild project. Also I've added full access to the bucket, since we'll be copying files to that bucket. In summary, the policy below grants the following permissions (account id is masked with 111111111111):

• Access to create new log groups in CloudWatch
• Access to create new log streams within the log group created by the build project
• Access to create new log events within the log stream created by the build project
• Access to pull data through Git to CodeCommit repository
• Full Access to our S3 bucket where the files will go

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
                "logs:CreateLogGroup",
                "s3:ListObjects"
            ],
            "Resource": "*",
            "Effect": "Allow",
            "Sid": "AccessLogGroupsS3ListObjects"
        },
        {
            "Action": [
                "codecommit:GitPull",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": [
                "arn:aws:logs:eu-west-1:111111111111:log-group:/aws/codebuild/
                 abelperez-stack-builder",
                "arn:aws:logs:eu-west-1:111111111111:log-group:/aws/codebuild/
                 abelperez-stack-builder:*",
                "arn:aws:codecommit:eu-west-1:111111111111:abelperez.info-web"
            ],
            "Effect": "Allow",
            "Sid": "AccessGitLogs"
        },
        {
            "Action": "s3:*",
            "Resource": [
                "arn:aws:s3:::www.abelperez.info",
                "arn:aws:s3:::www.abelperez.info/*"
            ],
            "Effect": "Allow",
            "Sid": "AccessS3staticBucket"
        }
    ]
}

Creating the service role

Go to IAM console, select Roles from the left hand side menu, click on Create Role. On the Select type of trusted entity screen, select AWS service EC2, Lambda and others and from the options, CodeBuild

Click Next: Permissions, at this point, we can create a policy with the JSON above or continue to Review and then add the policy later. To create the policy, click Create Policy button, select JSON tab, paste the JSON above, Review and Create Policy, then back to role permission screen, refresh and select the policy. Give it a name, something like CodeBuildRole or anything meaningful and click on Create Role to finish the process.

Creating the CodeBuild project

With all permissions set, let's start with the actual CodeBuild project, where we'll specify the source code origin, build environment, artifacts and role. On CodeBuild console, if it's the first project, click Get Started, otherwise select Build projects from the left hand side menu, and click on Create Project

Enter the following values:

• Project name* a meaningful name i.e "abelperez-stack-builder"
• Source provider* select "AWS CodeCommit"
• Repository* select the repository previously created
• Environment image* select "Use an image managed by AWS CodeBuild"
• Operating system* select "Ubuntu"
• Runtime* select "Node.js"
• Runtime version* select "aws/codebuild/nodejs:6.3.1"
• Buildspec name leave default "buildspec.yml"
• Artifacts: Type* select "No artifacts"
• Role name* select the previously created role

After finishing all the input, review and save the project.

Creating the build spec file

When creating the CodeBuild project, one of the input parameters is the Buildspec file name, which refers to the description of our build process. In this case, it's very simple process:

• BUILD: Create a directory dist to copy all output files
• BUILD: Copy all .html file to dist
• POST_BUILD: Synchronise all content of dist folder with www.abelperez.info S3 bucket

The complete buildspec.yml containing the above steps:

version: 0.2

phases:
  build:
    commands:
      - mkdir dist
      - cp *.html dist/

  post_build:
    commands:
      - aws s3 sync ./dist s3://www.abelperez.info/ --delete --acl=public-read

The last step is executed on post build phase, which is at the end of the all build steps when everything is ready to package / deploy or in this case ship to our S3 bucket. This is done by using the sync subcommand of s3 service from AWS Command line interface. It basically takes an origin and a destination and make them to be in sync.

--delete instructs to remove files in the destination that are not in the source, because by default they are not deleted.

--acl=public-read instructs to edit bucket objects' ACL, in this case read access to everyone.

At this point, we can remove the bucket policy previously created if we wish so, since every single file will be publicly accessible, that would allow to have other folders in the same bucket and not being accessible. It will depend on the use case for the website.

Let's test it

It's time to verify if everything is in the right place. We have the build project with some basic commands to run and assuming the above code is saved in a file named buildspec.yml at root level of the code repository, the next step is to commit and push that file to CodeCommit.

Let's go back to CodeBuild console, select the build project we've just created and click Start build, then choose the right branch (master in my case) and once again Start build.