incert

incert is a Go program that appends CA certificates to Docker images and pushes the modified image to a specified registry.

(this used to be named certko)

Installation

Binaries for various architectures are available from the releases page.

If you have a Go installation, you can install incert with the following command:

$ go install github.com/chainguard-dev/incert@latest

Alternatively, you can also build from source by cloning the repo and running go build.

Flags

incert supports the following flags:

  -ca-certs-file string
        The path to the local CA certificates file
  -ca-certs-image-url string
        The URL of an image to extract the CA certificates from
  -dest-image-url string
        The URL of the image to push the modified image to
  -image-cert-path string
        The path to the certificate file in the image (optional) (default "/etc/ssl/certs/ca-certificates.crt")
  -image-url string
        The URL of the image to append the CA certificates to
  -output-certs-path string
        Output the (appended) certificates file from the image to a local file (optional)
  -owner-group-id int
        The group ID of the owner of the certificate file in the image (optional)
  -owner-user-id int
        The user ID of the owner of the certificate file in the image (optional)
  -platform string
        The platform to build the image for (default "linux/amd64")
  -replace-certs
        Replace the certificates in the certificate file instead of appending them

Example

To append a corporate CA certificate to an image, use the following command:

$ incert -image-url=mycompany/myimage:latest -ca-certs-file=/path/to/cacerts.pem -dest-image-url=myregistry/myimage:latest

This will append the certificates in /path/to/cacerts.pem to the mycompany/myimage:latest image and push the modified image to myregistry/myimage:latest.

For security, incert outputs the pushed image reference (with digest) to stdout:

$ incert --image-url=gcr.io/dlorenc-chainguard/wolfi-base --ca-certs-file mycert.pem --dest-image-url gcr.io/dlorenc-chainguard/wolfi-base:new
Successfully appended CA certificates to image gcr.io/dlorenc-chainguard/wolfi-base:withcerts
gcr.io/dlorenc-chainguard/wolfi-base:withcerts@sha256:0cd4278e8072df5acd4956eb58ecba73024de47d9ceace3f0d39fb64e1b01ca6

Authentication

incert uses standard Docker credential helpers for authentication. To configure your credential helper, please follow the instructions in the Docker documentation.

Certificate Formats

Certificate files should be pem encoded and ready to append to a list of other pem certificates. They should look something like this:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----