Jenkins is a very popular ci solution and offer a lot of extensibility by plugins. However, updating these plugins while you are sitting behind a corporate firewall. I explain you what is the issue and how we solve it.

What is the problem?

Is there a way - or a tool - that let me setup the jenkins plugin site as proxy repo so that within Jenkins I can get the plugin updates from the proxy repo rather than the original site?

The issue arises specially in environments where you cannot have direct access to the internet. So in my scenario I have a Nexus Repo Server which has access to the internet. The Jenkins server has not. So my approach was to

1. Setup a proxy repo (let’s say https://nexus.intra/repository/updates.jenkins.io/ which is a proxy to https://updates.jenkins.io/
2. Configure Jenkins so that the plugins are gathered from the proxy repo. Thus I configure the plugin udate site to https://nexus.intra/repository/updates.jenkins.io/update-center.json

This does not work. I get the notification of new plugins, but when I try to download the plugin the connection fails, as within the update-center.json the pointer to the plugins is still https://updates.jenkins.io/. See here …

    updateCenter.post(
    ....
    ,"url":"http://updates.jenkins-ci.org/download/plugins/AnchorChain/1.0/AnchorChain.hpi",
    ....

So how to solve this?

My solution

One solution I have implemented is to modify the hosts file on the Jenkins host to point to the artifact repo when querying updates.jenkins-ci.org. However this requires a reverse proxy in front of your artifact repo.

1. On Jenkins host update the hosts file as follows

   <artifact repo ip> plugins.jenkins.io updates.jenkins.io updates.jenkins-ci.org mirrors.jenkins.io

2. Setup a reverse proxy in front of the artifact repo which handles traffic for updates.jenkins.io, updates.jenkins-ci.org, plugins.jenkins.io and mirrors.jenkins.io to your artifact repo

   If you are running your artifact repo in k8s your Ingress may look as follows:

   apiVersion: extensions/v1beta1
   kind: Ingress
   metadata:
   name: artifactory-repo-jenkins
   annotations:
       nginx.ingress.kubernetes.io/rewrite-target: /artifactory/remote-generic-updates.jenkins/
       nginx.ingress.kubernetes.io/upstream-vhost: "artifactory.intra"
       nginx.ingress.kubernetes.io/ssl-redirect: "false"
   spec:
   tls:
   - hosts:
       - updates.jenkins.io
       - updates.jenkins-ci.org
       - mirrors.jenkins.io
       secretName: artifactory-jenkins-ingress-cert
   rules:
   - host: jenkins.intra
       http:
       paths:
       - backend:
           serviceName: artifactory-artifactory
           servicePort: 8081
           path: /
   - host: updates.jenkins.io
       http:
       paths:
       - backend:
           serviceName: artifactory-artifactory
           servicePort: 8081
           path: /
   - host: updates.jenkins-ci.org
       http:
       paths:
       - backend:
           serviceName: artifactory-artifactory
           servicePort: 8081
           path: /
   - host: mirrors.jenkins.io
       http:
       paths:
       - backend:
           serviceName: artifactory-artifactory
           servicePort: 8081
           path: /

3. Optionally if you want to use ssl, you have to create a certificate which includes the urls as alternate names.

   [req]
   distinguished_name = req_distinguished_name
   req_extensions = v3_req
   prompt = no
   [req_distinguished_name]
   C = CH
   O=My Company
   OU = Artifactory
   CN = jenkins.intra
   [v3_req]
   keyUsage = keyEncipherment, dataEncipherment
   extendedKeyUsage = serverAuth
   subjectAltName = @alt_names
   [alt_names]
   DNS.1 = jenkins.intra
   DNS.2 = updates.jenkins-ci.org
   DNS.3 = plugins.jenkins.io
   DNS.4 = updates.jenkins.io
   DNS.5 = mirrors.jenkins.io

In addition, if you have restricted connection I recommend to white-list all mirrors for your artifact repository so it can get the artifacts properly

• plugins.jenkins.io
• updates.jenkins-ci.org
• mirrors.tuna.tsinghua.edu.cn
• ftp.yz.yamagata-u.ac.jp
• mirror.esuni.jp
• mirrors.seville-jam.es
• mirror.xmission.com
• archives.jenkins-ci.org
• ftp-chi.osuosl.org

You may find the post also on Stackoverflow.