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README.md

README

This image provides an OpenShift basicauthurl server which an administrator can use to implement custom authentication for OpenShift.

This directory contains the files necessary to build the image for a secure httpd server running on RHEL 7 that can respond to basic authentication requests as OpenShift requires.

The image must be deployed with server configuration that specifies the authentication method to be used and the security configuration.

Usage

This README assumes you are performing these commands on an installed and running OpenShift Enterprise master host. It may require adjustments for other environments.

First, choose a project for the basicauthurl service to live in. It can be the default project if you wish or another. This example assumes the basicauthurl project.

$ oc new-project basicauthurl

Build and deploy the image

A Docker image may be provided in the future. For now, you will need to build it from the source Dockerfile. You can directly use the OpenShift GitHub repository, or clone it to your own OpenShift-accessible git repository if you need to make any changes (e.g. to add an httpd module or build for a Linux other than RHEL).

$ oc new-app --name=basicauthurl --labels=name=basicauthurl \
             https://github.com/openshift/basic-authentication-provider-example
imagestreams/rhel
imagestreams/basicauthurl
buildconfigs/basicauthurl
deploymentconfigs/basicauthurl
A build was created - you can run `oc start-build basicauthurl` to start it.
Service "basicauthurl" created at <IP> with port mappings 8443.
Run 'oc status' to view your app.

You can use the resulting service IP for the server certificate and master config below. This is recommended.

If, instead, you would like the master to reach your authentication service via a route (which may not be a good idea for security reasons), you can create that route as follows:

$ oc expose service/basicauthurl --hostname=<correctly resolving name>

Then use oc edit route/basicauthurl to make the resulting route use passthrough or reencrypt TLS. Of course the route will only work from the master if you have deployed a router on OpenShift and the hostname in the route correctly resolves to it via DNS.

Specify the configuration

To configure this server on OpenShift, create a Kubernetes secret containing the necessary configuration files as described below. Note that the names below are how they are referred to in the secret. The actual file names you build the secret from could be anything.

  • conf

This file should contain the main httpd configuration directives that you need for authentication. The examples/ directory provides an example basicauth.conf that would be backed by an htpasswd-generated hash file. You could include directives for any httpd authentication module that is included in the image. (Note, the example ldap.conf will only work if the unsupported mod_ldap RPM is added to the image.)

This file will be placed in the container as /etc/authserver/include.conf and included by the secure server configuration.

  • conf-dir

This file, if present, should be a tarball of files that will be placed in the /etc/authserver/conf/ directory on the container. This can include anything needed outside the server configuration. For instance, it could include an htpasswd-created file for use with the example above.

  • cert, key, ca

In order to secure the connection between the master and the authentication server, the server should present a valid TLS configuration.

These files should include the server certificate, server key, and any necessary CA bundle required to secure the server with TLS. In order to create a properly secured server certificate, you will need to determine the desired address(es) for the master to reach the server. This must be either an IP for the service (created above) or some other address that will resolve correctly on the master, such as an /etc/hosts entry or DNS-resolved external route. Note that the master does not typically use the cluster DNS resolver (*.cluster.local).

For testing purposes, you can likely use the OpenShift tools to create a key and cert signed with the OpenShift CA, for example:

oadm create-server-cert --signer-cert=/etc/openshift/master/ca.crt \
                        --signer-key=/etc/openshift/master/ca.key  \
                        --signer-serial=/etc/openshift/master/ca.serial.txt \
                        --cert=cert.crt --key=key.key \
                        --hostnames=basicauthurl.example.com,172.30.137.253

The CA certificate can just be a copy of the cert.crt if no CA is needed. You could also use a self-signed certificate here and include it as the CA cert in the master config (below). Only the master needs to be able to validate the secure connection to the auth server.

Creating the secret

You can bundle up these files into a secret with the oc secrets new command. Continuing with the htpasswd auth example, here is a demonstration:

$ mkdir secrets; cd secrets
$ cp ../examples/basicauth.* .
$ tar zfc conf.tgz basicauth.htpasswd
[... create or copy the key/certs ...]
$ oc secrets new httpd-auth conf=basicauth.conf conf-dir=conf.tgz \
                             key=key.key cert=cert.crt ca=ca.crt

This secret becomes a volume that authorized pods can mount. The service account, generally default, that deploys the server will need access to the secret to enable mounting it:

$ oc secrets add serviceaccount/default secrets/httpd-auth --for=mount

Next, add the secret volume to the server deployment configuration:

$ oc volume  dc/basicauthurl --add --type=secret \
                             --secret-name=httpd-auth \
                             --mount-path=/etc/secret-volume

An automated build should already be running, and once it completes successfully, it should be deployed with the content you specified in the secret. If it was already deployed prior to the step above adding the secret volume, it will be redeployed once the modification occurs.

OpenShift Master setup:

Now to have the master use your authentication, specify the following in the master's configuration file (/etc/openshift/master/master-config.yaml for OpenShift Enterprise):

  identityProviders:
  - challenge: true
    login: true
    name: basicauthurl
    provider:
      apiVersion: v1
      kind: BasicAuthPasswordIdentityProvider
      url: https://<serviceIP or name>:8443/validate
      ca: /etc/openshift/master/ca.crt

The restart the master.

# systemctl restart openshift-master

Following the htpasswd example, you should now be able to login as "bob" with password "redhat".

Modifying the configuration

With everything in place, reconfiguration just requires updating the secret. To do so, delete and recreate the secret, add access for the service account again, and redeploy.

$ oc delete secrets/httpd-auth
$ oc secrets new httpd-auth conf=basicauth.conf conf-dir=conf.tgz key=key.key cert=cert.crt ca=ca.crt
$ oc secrets add serviceaccount/default secrets/httpd-auth --for=mount
$ oc deploy basicauthurl --latest

For modifications to the image itself, update the git repository it is based on and run the build:

$ oc start-build basicauthurl

It will automatically build from source and re-deploy.

To scale up the service such that it will not be interrupted by the loss of a node, just scale up the deployment config and redeploy it:

$ oc scale dc/basicauthurl --replicas=2
$ oc deploy basicauthurl --latest

(You can scale the existing deployment, but it is simplest to just redeploy.)

TODO:

  • The intention is not to continue with a mod_php script. Right now this is primarily a prototype for hosting a basicauthurl server on OpenShift itself.
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