curl (77) problem with the SSL CA cert

• Default bundle paths: /etc/ssl/certs/ca-certificates.crt (Debian), /etc/pki/tls/certs/ca-bundle.crt (RHEL)
• Alpine: apk add ca-certificates; then update-ca-certificates
• Docker scratch: copy the bundle from an unpacked image
• --cacert /path/to/ca.pem — per-request override
• -k / --insecure skips verify — debug only, never production

# Debian/Ubuntu: install bundle
$ apt-get install ca-certificates

# Alpine (Docker)
$ apk add --no-cache ca-certificates
$ update-ca-certificates

# Debug — which bundle curl sees
$ curl -v https://example.com 2>&1 | grep -i "CAfile\|CApath"

# Default via env
$ export CURL_CA_BUNDLE=/etc/ssl/certs/ca-certificates.crt

• Unknown issuer
• Java PKIX

CA certificates are crucial for establishing secure connections over the internet. They are used to verify the authenticity of SSL/TLS certificates presented by servers, ensuring that data transmitted between clients and servers remains secure.

When curl encounters a curl error 77, it indicates that the CA certificate bundle is either missing or unreadable. This can lead to failed HTTPS requests, which can compromise the security of data transfers.

Here are key points to understand about CA certificates:

• Root Certificate Authorities (CAs): These are trusted entities that issue and manage digital certificates. Browsers and operating systems maintain a list of trusted root CAs.
• Intermediate Certificates: These serve as a bridge between the root CA and the SSL certificates installed on servers. They help establish a chain of trust.
• CA Bundle: A CA bundle is a file that contains multiple CA certificates. It is used by tools like curl to validate the SSL certificates presented by servers.

Understanding the role of CA certificates can help you troubleshoot issues related to SSL connections and fix curl error 77 efficiently.

Encountering curl error 77 can be frustrating, but knowing how to troubleshoot the common causes can save you time and effort. Here are some steps to identify and resolve the issue:

• Check CA Bundle Path: First, verify the path to your CA bundle. Run the following command:

If the file does not exist, you may need to install or reinstall the CA certificates package:

• Check Permissions: Ensure that the CA bundle file has the correct permissions. You can check this with:

Make sure the file is readable by the user running the curl command.

• Using Containers: If you are working within a container, ensure that the CA certificates are installed. For example, in an Alpine-based container, you can add CA certificates with:

After making these changes, try running your curl command again to see if the error persists.

The CURL_CA_BUNDLE environment variable allows you to specify a custom CA certificate bundle for curl. If this variable points to a non-existent or inaccessible file, it can trigger curl error 77. Here’s how to configure it correctly:

To set the CURL_CA_BUNDLE variable, use the following command:

Replace /path/to/your/ca-bundle.crt with the actual path to your CA bundle file. Ensure that the file exists and is readable:

• Verify the file:

If the file is missing, you will need to obtain a valid CA bundle. You can download a CA bundle from curl's official website.

After setting the environment variable, you can test your curl command:

If the command executes successfully, it indicates that the CURL_CA_BUNDLE variable is configured correctly. If you continue to face issues, recheck the path and permissions of the specified CA bundle.