Working with custom domain mappings

Domain mappings provide the URL route to your Code Engine application or function within a project. With Code Engine, these mappings are automatically created, by default, whenever you deploy an application or create a function. However, you can map your own custom domain to a Code Engine application or function. This option routes requests from your custom URL to your application or function. You can use the Code Engine console or CLI.

If you want to target your Code Engine application or function with a domain that you own, you can use a custom domain mapping. When you set a custom domain mapping in Code Engine, you define a one-to-one mapping between your fully qualified domain name (FQDN) and a Code Engine application or function in your project.

A custom domain mapping must point to only one Code Engine application or function. However, you can configure multiple domain mappings to a single application or function.

To work with custom domain mappings in Code Engine, complete the following steps. Notice that some steps are completed outside of Code Engine.

Review the Considerations before you use custom domain mappings in Code Engine.
Obtain your custom domain from a domain registrar (outside of Code Engine).
Configure a custom domain mapping in Code Engine for your application or function (from the Code Engine console or CLI).
Complete the custom domain configuration with your domain registrar (outside of Code Engine).

After you complete the custom domain setup with your domain registrar, and you configure a domain mapping for your application or function in Code Engine, test the domain mapping.

In Code Engine, you can view, update, or delete domain mappings to your applications or functions.

Considerations before you use custom domain mappings in Code Engine

Before you implement custom domain mappings in Code Engine, be aware of the following considerations:

Use only custom domain mappings for domains that are protected with a SSL/TLS certificate, which a public, trusted certificate authority (CA) signs.
You can define custom domain mappings that point to public domain names.
If your domain name can be resolved only by a nonpublic domain name system (DNS), provide a certificate that lists the domain name and is signed by a public, trusted CA.
Provide the entire certificate chain, starting with the certificate that corresponds to the custom domain, followed by all intermediate certificates up to the root certificate.
You cannot use self-signed certificates.
You cannot use certificates that are signed by an untrusted or a nonpublic enterprise CA.
Your certificate must have an expiry date that is set.

Obtaining a custom domain and its TLS certificate and private key

Before you configure custom domain mappings in Code Engine, you must first obtain your custom domain from a domain registrar (outside of Code Engine).

From a domain registrar, obtain your custom domain; for example, www.example.com.
Obtain your SSL/TLS certificate for your custom domain:
- You can create a certificate that is not self-certified, by using the Let's Encrypt service and Certbot. If the custom domain is within your control and you want to quickly create a certificate, you can use Certbot and the Let's Encrypt services to obtain a certificate.
- You can obtain a signed certificate from a trusted authority. This type of digital certificate is used to establish communication privacy between a server and a client. These certificates contain information that is used to create trusted and secure connections between endpoints. You must also obtain a matching private key for the TLS certificate.
  
  You can obtain your certificate and key from your CA. Obtain a signed SSL/TLS certificate for your custom domain. For security reasons, Code Engine supports only custom domain mappings that are configured with a TLS/SSL certificate that is signed by a public, trusted CA.

How can I use Certbot and the Let's Encrypt service for my custom domain?

In an enterprise environment, work with your corporate domain administrator to obtain the necessary certificates. However, if the custom domain is within your control and you want a quick certificate, then you can use Certbot and the Let's Encrypt service to obtain a certificate:

Install Certbot. Certbot is a client for the Automatic Certificate Management Environment (ACME) protocol for automating interactions between a CA and a server. The Let's Encrypt service uses this client to verify domain ownership and issue certificates. From the Certbot documentation, select Other as the software and select the operating system for your workstation to obtain the applicable information to install the Certbot command line.
Run the following command to create your certificate. This example command creates a certificate for the example.com and www.example.com custom domains. Be sure to update the command for your own custom domain.
```
certbot certonly --manual --preferred-challenges dns --email webmaster@example.com --server https://acme-v02.api.letsencrypt.org/directory --agree-tos --domain example.com --domain www.example.com
```
To verify that you own the domain, set a TXT record with your domain registrar for the domains that you requested in the previous step with values that were provided with the Certbot tool output; for example, _acme_challenge.example.com and _acme_challenge.ww.example.com. After you set the TXT record, continue with the Certbot command.
Certbot retrieves the certificate that is signed by Let's Encrypt. The location where the certificate is stored is provided by the Certbot output. Find the fullchain.pem and privkey.pem files.

Example command to run Certbot on an Ubuntu system

sudo certbot certonly --manual --preferred-challenges dns --email webmaster@example.com --server https://acme-v02.api.letsencrypt.org/directory --agree-tos --domain example.com --domain www.example.com

Example output for the certificate request for example.com and www.example.com

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Please deploy a DNS TXT record under the name:
_acme-challenge.example.com.
with the following value:
<MASKED>
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Press Enter to Continue
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Please deploy a DNS TXT record under the name:
_acme-challenge.www.example.com
with the following value:
<MASKED>
(This must be set up in addition to the previous challenges; do not remove,
replace, or undo the previous challenge tasks yet. Note that you might be
asked to create multiple distinct TXT records with the same name. This is
permitted by DNS standards.)
Before continuing, verify the TXT record has been deployed. Depending on the DNS
provider, this may take some time, from a few seconds to multiple minutes. You can
check if it has finished deploying with aid of online tools, such as the Google
Admin Toolbox: https://toolbox.googleapps.com/apps/dig/#TXT/_acme-challenge.www.example.com.
Look for one or more bolded line(s) below the line ';ANSWER'. It should show the
value(s) you've just added.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Press Enter to Continue
Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/example.com/fullchain.pem
Key is saved at: /etc/letsencrypt/live/example.com/privkey.pem
This certificate expires on 2023-02-01.
These files will be updated when the certificate renews.
NEXT STEPS:
- This certificate will not be renewed automatically. Autorenewal of --manual certificates requires the use of an authentication hook script (--manual-auth-hook) but one was not provided. To renew this certificate, repeat this same certbot command before the certificate's expiry date.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
If you like Certbot, please consider supporting our work by:
 * Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate
 * Donating to EFF: https://eff.org/donate-le
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Your certificate is ready.

How do I obtain the CNAME record for a custom domain mapping?

Code Engine provides the CNAME target for your defined custom domain mapping.

To obtain the CNAME record from the Code Engine console, open your defined custom domain mapping and view the Update domain mapping page. Open the Update domain mapping page in one of the following ways:

From the Domain mappings table, click in the row of your defined custom domain.
Click the Actions icon > Edit to edit the mapping.

From the Update domain mappings page, you can obtain the CNAME target value. For example, the www.example.com mapping has the custom.abcdabcdabc.us-east.codeengine.appdomain.cloud CNAME value, where abcdabcdabc is an automatically generated unique identifier and us-east is the region of your project.

To obtain the CNAME record with the CLI, use the ibmcloud ce domainmapping get command. For example,

ibmcloud ce domainmapping get --domain-name www.example.com

Example output

Getting domain mapping 'www.example.com'...
OK

Domain Name:  www.example.com
CNAME:        custom.abcdabcdabc.us-south.codeengine.appdomain.cloud
Target Name:  myapp
Target Type:  app
TLS Secret:   mytlssecret
Status:       ready

After you have the CNAME target, you are ready to add the CNAME record entry to the DNS settings of your custom domain. Note that publishing of the CNAME record with the domain registrar can take some time to populate the DNS changes in the internet.

Configuring custom domain mappings in Code Engine

You are now familiar with the concepts of working with custom domain mappings and you obtained your custom domain from a domain registrar. You are ready to configure your Code Engine applications or functions to use custom domain mappings. See:

Viewing domain mappings

Viewing domain mappings from the console

You can view a listing of all automatically generated and custom domain mappings for your application or function from the console. By default, the contents of the table are scoped to custom domain mappings. Use the Type filter to modify the view.

This view displays information about the expiration of the certificate that is associated with your mapping. When the certificate expires, the application or function is no longer reachable with the domain mapping, and this condition yields an SSL error. If you have a certificate that is about to expire, update the custom domain mapping to use an updated certificate.

This view also displays information about the specific application or function that is associated with the domain mapping, and the type of the domain mapping. For mappings that Code Engine generates, the type can be System-public, System-private, or System-internal. For custom domain mappings that you create, the type is Custom.

After your project is in Active status, click the name of your project on the Code Engine Projects page.
From the overview page, click Domain mappings.
From the domain mappings page, view a listing of the defined domain mappings for your existing applications or functions. The Type indicates whether the mapping is automatically generated or if it is a custom domain mapping.

Viewing domain mappings with the CLI

To view a listing of all custom domain mappings for your applications or functions with the CLI, use the ibmcloud ce domainmapping list command. For example,

ibmcloud ce domainmapping list

Example output

Listing domain mappings...
OK

Name              CNAME                                                        Target  Target-Type  Status  Secret Name  Age
www.example.com   custom.abcdabcdabc.us-south.codeengine.appdomain.cloud       myapp   app          ready   mytlssecret  36m

To view a listing of all domain mappings for your applications or functions, including both custom domain mappings that you create and automatically generated domain mappings that Code Engine creates, specify the --all option with the ibmcloud ce domainmapping list command. Custom domain mappings display a value for CNAME.

Updating domain mappings

When you create a custom domain mapping, the TLS secret is valid until the certificate expires. From the domain mapping page, you can view information about the remaining days until the certificate expires.

It is important to know whether the certificate that is used with your custom domain lists multiple domain names, or if it uses a wildcard certificate. When your certificate is close to expiring (or is expired), edit the existing TLS secret for the domain mapping with updated credentials. Do not create a different TLS secret with updated credentials for your domain mapping.

Updating a domain mapping from the console

Suppose the custom domain mapping for www.example.com has a certificate that expires soon. You can update the domain mapping from the console to use an updated certificate or even replace the TLS secret for the mapping. You can also update your domain mapping to point to a different application or function in your project.

From the Code Engine Projects page, go to your project.
From the Overview page, click Domain mappings.
From the Domain mappings page, click the Actions icon > Edit to edit the mapping. Or, you can click in the row of your defined custom domain to update the mapping.
From the "Update a domain mapping" pane, you can change the application or function that is associated with this domain mapping. Alternatively, you can replace or update the TLS secret for this mapping.
Click Update to save your changes.

After you update the mapping, you can view the list of domain mappings for the most recent changes.

Updating a domain mapping with the CLI

To update a custom domain mapping, use the ibmcloud ce domainmapping update command.

Suppose the custom domain mapping for www.example.com has a certificate that expires soon. You can update the domain mapping to use an updated certificate or even replace the TLS secret for the mapping with the --tls-secret option. You can also use the --target option to update your domain mapping to point to a different application or function in your project.

The following example updates the www.example.com custom domain mapping to use an updated TLS secret called mytlssecret.

Update the TLS secret mytlssecret with updated certificate and private key information, which are contained in the mycertchain2.txt and myprivatekey2 files on your local workstation.
```
ibmcloud ce secret update --name mytlssecret --cert-chain-file  mycertchain2.txt --private-key-file myprivatekey2.txt
```
Example output
```
Updating secret mytlssecret..
OK
```

Update the domain mapping to use the updated TLS secret.

ibmcloud ce domainmapping update --domain-name www.example.com --tls-secret mytlssecret2

Example output

Getting domain mapping 'www.example.com.org'...
Updating domain mapping 'www.example.com.org'...

Deleting domain mappings

When you delete a domain mapping, you are removing the association of your Code Engine application or function with your custom domain mapping within Code Engine. This action does not delete the associated application, function, or TLS secret.

Deleting an application or function that is referenced in a domain mapping also deletes any custom domain mapping that is associated with the application or function.

When you delete a custom domain mapping, and domain DNS settings remain, your traffic is still routed to the Code Engine project. For example, the CNAME points to the Code Engine project can still be set. However, the request is answered with a 404 (not found) error message. Ensure that the associated CNAME record for the fully qualified domain name is updated in the DNS settings by the domain registrar.

Deleting domain mappings from the console

From the console, you can delete only domain mappings of type Custom. Domain mappings that Code Engine automatically generate cannot be deleted.

To delete a custom domain mapping from the console,

From the Code Engine Projects page, go to your project.
From the Overview page, click Domain mappings to view a listing of defined domain mappings.
(Optional) Click Type to filter the domain mappings by type.
From the Domain mappings page, delete the custom domain mapping that you want to remove from your application or function. Click the Actions icon > Delete to delete the mapping.

Deleting domain mappings with the CLI

To delete a custom domain mapping with the CLI, use the ibmcloud ce domainmapping delete command.

You can delete only custom domain mappings; you cannot delete Code Engine-generated domain mappings. Run the ibmcloud ce domainmapping list command to display a list of custom domain mappings with the CLI. A custom domain mapping has a generated CNAME record. In the CLI, you can obtain the generated CNAME value for a specified custom domain mapping by using the ibmcloud ce domainmapping get command.

ibmcloud ce domainmapping delete --domain-name www.example.com -f

Example output

Deleting domain mapping 'www.example.com'...
OK

Next steps

You are now familiar with working with custom domain mappings, and you have obtained a custom domain with its TLS certificate and private key. You are ready to configure a custom domain mapping in Code Engine for your application or function.