Tuesday, 6 February 2018

Serverless static website - part 6

Up to this point we've created a simple HTML page and set up all the plumbing to make it visible to the world in a distributed and secure way. Now, if we want to update the content, we can either go to S3 console and upload manually the files or from the AWS CLI synchronise a local folder with a bucket. None of those ways seem to scale in the long run. As a developer I like to keep things under control, even more, under source control.

It can be done by using any popular cloud hosted version control systems, such as github, but in this example I'll use the one provided by AWS, it's called CodeCommit and it's a Git repository compatible with all current git tools.

Creating the repository

In CodeCommit console, which can be accessed by selecting Services, then under Developer Tools, select CodeCommit. Once there, click on Create repository button, or Get started if you haven't created any repository before.

Next, give it a name and a description and you'll see something like this:

Creating the user

Now, we need a user for ourselves or if someone else is going to contribute to that repository. There are many ways to address this part, I'll go for creating a user with a specific policy to grant access to that particular CodeCommit repository

In IAM (Identity and Access Management) console, select Users from left hand side menu, then click Add user. Next, give it a name and Programmatic access, this user won't access the console so it doesn't need login and password, not even access keys.

Click Next, Skip permissions for now, we'll deal with that in the next section. Review and create the user.

Creating the policy

Back to IAM console dashboard, select Policies from the left menu, then click on Create policy, select JSON tab and copy the following:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowGitCommandlineOperations",
            "Effect": "Allow",
            "Action": [
                "codecommit:GitPull",
                "codecommit:GitPush"
            ],
            "Resource": [
                "arn:aws:codecommit:::abelperez.info-web"
            ]
        }
    ]
}

Details about creating policies is beyond the scope of this post, but essentially this policy grants pull and push operations on abelperez.info-web repository. Click Review Policy and give it a meaningful name such as CodeCommit-MyRepoUser-Policy or something that states what permissions are granted, just to keep everything organised. Create the policy and you'll be able to to see it if filtering by the name.

Assigning the policy to the user

Back to IAM console dashboard, select Users, select the user we've created before, on tab Permissions, click Add Permissions

Once there, select Attach existing policies directly from the top three buttons. Then, filter by Customer managed policies to make it easier to find our policy (the one created before). Select the policy, Review and Add Permissions.

When it's done, we can see the permission added to the user, like below.

Granting access via SSH key

Once we've assigned the policy, the user should have permission to use git pull / push operations, now we need to link that IAM user with a git user (so to speak). To do that, CodeCommit provides two options: via HTTPS and SSH. The simpler way is using SSH, it only requires to upload the SSH public key to IAM user settings, then add some host/key/id information to SSH configuration file and that's it.

In IAM console, select the previously created user, then on Security Credentials tab, scroll down all the way to SSH keys for AWS CodeCommit, then click on Upload SSH public key button, paste your SSH public key. If you don't have one created yet, have a look at here and for more info, here. Click Upload SSH public key button and we are good to go.

If you are interested in accessing via HTTPS, then have a look at this documentation page on AWS website.

Back to CodeCommit console, select the repository previously created, then on the right hand side, click Connect button. AWS will show a panel with instructions, depending on your operating system, but it's essentially like this:

The placeholder Your-IAM-SSH-Key-ID-Here refers to the ID auto generated by IAM when you upload your SSH key and it has the format like APKAIWBASSHIDEXAMPLE

Let's test it

The following command sequence has been executed after setting up all the previous steps on AWS console. Started by cloning an empty repo, then created a new file. Added and committed that file to the repository and finally pushed that commit to the remote repository

abel@ABEL-DESKTOP:~/Downloads$ git clone ssh://git-codecommit.eu-west-1
.amazonaws.com/v1/repos/abelperez.info-web
Cloning into 'abelperez.info-web'...
warning: You appear to have cloned an empty repository.
abel@ABEL-DESKTOP:~/Downloads$ cd abelperez.info-web/
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ ls
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ echo "<h1>New file</h1>" > index.html
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ cat index.html 
<h1>New file</h1>
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git add index.html 
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git commit -m "first file"
[master (root-commit) c81ad93] first file
 Committer: Abel Perez Martinez <abel@ABEL-DESKTOP>
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

 1 file changed, 1 insertion(+)
 create mode 100644 index.html
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git status
On branch master
Your branch is based on 'origin/master', but the upstream is gone.
  (use "git branch --unset-upstream" to fixup)
nothing to commit, working tree clean
abel@ABEL-DESKTOP:~/Downloads/abelperez.info-web$ git push
Counting objects: 3, done.
Writing objects: 100% (3/3), 239 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To ssh://git-codecommit.eu-west-1.amazonaws.com/v1/repos/abelperez.info-web
 * [new branch]      master -> master

After this, as expected, the new file is now visible from CodeCommit console.

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