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SSL/TLS Certificates for Object Storage with Edge Services

Reviewed on 13 May 2024

This document contains information to help you with SSL/TLS certificates that enable your bucket’s content to be served over HTTPS, through your customized Edge Services domain.

Introduction

What is an SSL/TLS certificate?

An SSL/TLS certificate is a digital certificate that enables an encrypted connection between a client and a web server over HTTPS.

You may hear certificates referred to as “SSL certificates”, “TLS certificates” or “SSL/TLS certificates”. These are all the same thing. SSL (Secured Socket Layer) was the protocol initially used for encryption, though it has now been replaced with TLS (Transport Layer Security).

SSL/TLS certificates contain a public key, which corresponds to a separate private key. These work as a pair. When a client wants to establish an encrypted connection to a host, it requests the host’s certificate. The host shares the certificate, which includes the public key (the private key is never shared and is kept by the host). The client checks the certificate, and uses the host’s public key to encrypt the data that it transfers to the host. The host uses its private key to decrypt the data that has been encrypted by the public key.

The private key is also used by the host for generating digital signatures, while the public key is used by clients for verifying those signatures.

When and why do I need an SSL/TLS certificate for Edge Services?

When you enable Edge Services, initially your bucket content is served through the standard Edge Services endpoint, e.g. https://bucket-name.svc.edge.scw.cloud. Scaleway’s own SSL/TLS certificate, which covers this subdomain, is used to establish the encrypted connection between client and host. If you do not want to customize the standard Edge Services endpoint, you do not need to worry about creating SSL/TLS certificates.

However, if you choose to customize your Edge Services endpoint with your own subdomain, Scaleway’s own SSL/TLS certificate cannot longer be used to establish encrypted connections to your subdomain. Client connections are now initially going to a different domain which needs to be “guaranteed” by its own certificate (despite the CNAME record for the subdomain pointing to the Scaleway endpoint).

Therefore, when you customize your Edge Services endpoint with a subdomain, you are prompted to generate or upload an SSL/TLS certificate for that subdomain.

How can I provide an SSL/TLS certificate for my Edge Services customized domain?

You will be prompted to choose one of the following options when customizing your domain:

  • Generate a Let’s Encrypt certificate: Scaleway generates a free, managed Let’s Encrypt certificate for your domain and automatically renews it as necessary.

  • Select an existing certificate from Secret Manager: You select a certificate that you have already uploaded in Scaleway Secret Manager.

  • Manually import a certificate into Secret Manager: You can manually create your own certificate and import it. It will be stored in Scaleway Secret Manager (check the dedicated pricing page).

Generating a managed Let’s Encrypt certificate

This is the hassle-free option if you do not want to create or manage your own SSL/TLS certificate. Scaleway takes care of generating a certificate for your customized domain in the correct format. The certificate is automatically renewed before it expires. This option is available for free: it costs you nothing for Scaleway to generate and manage a Let’s Encrypt certificate for your domain.

You must ensure that you have correctly set the CNAME record for your domain. Without having done this, the Let’s Encrypt certificate option in the console will not be available. It is also important to check the CNAME is correctly set up so that the certificate is properly generated and reviewed.

Note that you will not have access to the generated certificate itself in Secret Manager or elsewhere. It is entirely generated and managed “behind the scenes”, and is not configurable by the user. If you reset your domain, or disable Edge Services, Scaleway automatically deletes the generated Let’s Encrypt certificate.

Troubleshooting

Errors

If there is a problem generating your managed Let’s Encrypt certificate, an error will be displayed. See the table below for help resolving these errors.

ErrorSolution
Too many certificates already issued for this domainWait, before retrying. This error occurs when you hit the limit of generating 50 Let’s Encrypt certificates in a rolling 7 day period for the same domain.
Internal managed certificate errorOpen a support ticket. There has been an unspecified error in generating a managed Let’s Encrypt certificate for your subdomain.
Certificate cannot be renewed - Your CNAME record is no longer accurateYour CNAME record has either been deleted or modified. Without a correct CNAME record, we cannot renew your managed Let’s Encrypt certificate. Rectify your CNAME record, and when Edge Services detects the correct record exists, your certificate will be automatically renewed.

Using your own certificate

If you wish to use your own certificate, rather than the option of generating a managed Let’s Encrypt certificate, take into account the following points.

Accepted certificate types

Types of validation:

  • Self-signed certificates. Certificates for Edge Services must be signed by a Certificate Authority (CA)
  • Domain Validated Certificate. The CA simply checks that the applicant owns the domain.
  • Extended/Organization Validation Certificate. The applicant must pass more in-depth validation procedures and checks by the CA.

Types of domain coverage:

  • Single domain certificate. Secures a single domain or subdomain. Note that the certificate must be for your-sub.domain.com, where the subdomain corresponds to the subdomain for Edge Services. A single domain certificate simply for yourdomain.com would not be acceptable, as it would not cover the subdomain for Edge Services.
  • Wildcard certificate. Secures multiple subdomains for a domain, using a wildcard * symbol. The Common Name of the certificate should look like *.yourdomain.com.
  • Multi-domain (MD) / Subject Alternative Name (SAN) / Unified Communications Certificate (UCC) certificate. Secures multiple explicitly-defined fully qualified domain names (www.yourfirstdomain.com, sub.yourfirstdomain.com, yourfirstdomain.com, yourseconddomain.com, sub.yourseconddomain.com etc.)

PEM format certificate chain

Edge Services requires that you import your certificate as a PEM-formatted certificate chain, which includes the private key. PEM format is Base64 encoded ASCII, and by definition includes lines stating -----BEGIN x----- and -----END x-----.

Your PEM formatted certificate chain should look like this:

-----BEGIN PRIVATE KEY-----
(private key here)
-----END PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
(primary certificate (aka server certificate) here)
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
(intermediate certificate here)
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
(root certificate here)
-----END CERTIFICATE-----
SectionContainsSubject (issued for)Issued and signed by
Private keyThe private key file for the certificate
Primary/server certificateThe certificate issued by the CA for your domain nameYour name and public keyCA
Intermediate certificateThe intermediate certificate chaining your primary certificate to the root certificateCA’s name and public key.Root CA
Root certificateThe root certificate by the CA, for the trusted CA itselfThe Root CA’s name and public keyRoot CA (self signed)

Note that in certain cases an intermediate certificate may not be necessary, if the root certificate chains directly to the primary/server certificate. The crucial thing is that the subject and issuers of each certificate form a coherent chain of validation. If a certificate is issued by an authority that is not present in the chain, an error will occur.

Tip

You can use the OpenSSL utility to convert certificates and keys from other formats to PEM, from the command line. Once installed, use a command like the following:

openssl x509 -in cert.crt -out cert.pem
openssl x509 -in cert.der -out cert.pem
openssl x509 -in cert.cer -out cert.pem

When you have your key, your server certificate and your root certificate all in separate files, you can use the cat command to chain them together into one file, ready to be copied and pasted:

cat private_key.pem cert.pem root_cert.pem > cert_chain.pem

Tips for creating a certificate

In general, SSL/TLS certificates can either be self-signed (signed by the subject of the certificate, e.g. the owner of the domain) or CA-signed (signed by a third party Certificate Authority which is publicly trusted).

Self-signed certificates cannot be used with Edge Services, all certificates must be signed by a CA that is known and trusted by Edge Services.

To get an SSL/TLS certificate for your domain or subdomain, you need to generate a Certificate Signing Request (CSR) and submit it to a Certificate Authority (CA) for them to validate your domain, who then send you a signed certificate. You may be able to carry out this procedure via your hosting provider, or from the command line.

CAs of private companies whose primary business is not SSL or domains may not be trusted by Edge Services. If you encounter a self-signed certificate error with Edge Services, but you believe your certificate is legitimately signed by an official CA, open a support ticket to tell us.

Tip

To get a working Let’s Encrypt certificate using certbot on the command line, follow the steps below:

  1. Install certbot on your machine.
  2. Open a terminal and run the following command, inserting your subdomain where shown:
    sudo certbot certonly --manual --preferred-challenges dns -d <your-subdomain.your-domain.ext>
    The command returns a token and asks you to create a TXT record in your DNS.
  3. Go to your domain/DNS provider and create a TXT record. The record name should be _acme-challenge.your-subdomain.your-domain.ext and the record must contain the token provided by certbot. Make sure the record has a short TTL in case you have to modify it for debugging purposes.
  4. Return to the terminal and press Enter once your record is ready. Certbot starts the verification process. If it succeeds, the certificate is downloaded to your machine in two files: the private key and the certificate.
  5. Concatenate the two files into one, using the following command:
    cat privkey.pem fullchain.pem > certificate.pem
  6. Delete the TXT record from your DNS.

Uploading your certificate

When you configure your customized domain with Edge Services for the first time, you are prompted to upload your certificate. You can do so in two ways:

  • Select an existing certificate that you have stored in a secret in Scaleway Secret Manager. The secret must be of the certificate type in order to be visible to Edge Services. The type can be defined when creating a secret via the API, but not via the console. For that reason, if you prefer to use the console to create your certificates, we suggest using the next option:
  • Manually import a certificate into Scaleway Secret Manager, directly from the Edge Services Configure domain wizard (copy and paste the PEM formatted chain). Your certificate will be automatically stored in Secret Manager, held in a secret that automatically inherits the type “certificate”.

Keeping your certificate up to date

SSL/TLS certificates all expire at some point. If your certificate expires before you upload a new one, you will see an error like this on your Edge Services dashboard:

You must renew your certificate or create a new one. A number of tools are available to ensure that certificates are automatically renewed before expiry, for example Certbot for LetsEncrypt. However, since Certbot or other tools for automatically renewing certificates are not currently integrated into Edge Services, you will need to manually update the certificate via the Scaleway console.

When you have your up to date certificate, go to Secret Manager in the console, and access the secret that contains your certificate. Create a new version of the secret, to hold the up to date certificate. Edge Services will automatically detect and use the most recent enabled version of the secret. You can nonetheless choose to disable or delete the old version(s) as you prefer, which will also save your billing costs (since you are billed per version).

Tip

If you change your customized subdomain to something new, you will need to generate and import a new certificate for that subdomain. In this case, it is recommended to create a new secret to hold the new certificate, rather than creating a new version of an existing secret.

Troubleshooting

Errors

If Edge Services detects a problem with your certificate, an error will be displayed. See the table below for help resolving these errors.

ErrorSolution
Certificate formatMake sure your certificate is in PEM format.
Certificate private key formatMake sure your private key is in PEM format.
Missing server certificateMake sure the server certificate (which validates your own subdomain) is included in the PEM-formatted chain.
Missing private keyMake sure your private key is included in the PEM-formatted chain.
Missing root certificateMake sure a valid root certificate is included in the PEM-formatted chain.
Wrong orderMake sure the server certificate (which validates your own subdomain) is listed before the intermediate and root certificates in the PEM-formatted chain
Too many private keysMake sure the PEM-formatted chain includes only one corresponding private key
Self-signed certificates not allowedCreate and upload a certificate issued by a recognized certificate authority. If you receive this error but believe your certificate is legitimately signed by an official CA, open a support ticket to tell us.
Invalid intermediate or root certificate authorityMake sure each Issuer field matches the Subject of the next certificate in the PEM-formatted chain.
Incorrect root certificateMake sure your server certificate chains up to the provided root(s) certificate(s) in the PEM-formatted chain.
Private key and certificate mismatchMake sure the private key in the PEM-formatted chain matches the server certificate.
Subdomain and server certificate mismatchMake sure the subdomain you configured for Edge Services matches that of the server certificate.
Certificate expiredCreate a new certificate and import it.

If any of these errors are detected while you are initially configuring your subdomain, you will be blocked from continuing until the error is fixed.

However, these errors may also be detected and displayed on your Edge Services dashboard even after you have initially successfully configured your subdomain and certificate. This could be the case, for example, if your certificate has since expired, or you have modified your subdomain without modifying the certificate, or you have modified the certificate in Secret Manager. In this case, your initial certificate will remain in use by Edge Services until the error is fixed, but clients may see an error in their browser as they try to access your customized domain.

To fix the problem, you must generate a valid certificate, and then do one of the following:

  • Use Edge Services to import a new certificate directly
  • Create a new secret to hold the certificate in Secret Manager, and edit your customized endpoint with Edge services to tell it to use this secret
  • Create a new version of the existing secret holding your expired certificate, where the new version contains a valid certificate. If Edge Services is already using this secret, it will automatically detect and use the new version - it always uses the most recent enabled version of a secret.

Secret not visible for selection in Edge Services

You may find that a certificate you have stored in Secret Manager is not available for selection from Edge Services. This is probably because the secret does not have the “certificate” type, which is necessary for it to be visible to Edge Services. The “type” of a secret can be defined when creating a secret via the API, but not via the console. For that reason, if you prefer to use the console to create your certificates, we suggest manually importing the certificate via Edge Services rather than via Secret Manager. This way, it will automatically inherit the “certificate” type.

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