add info about el 7.9, 7.8 and 7.7 vault (#96)

Co-authored-by: Alex Baranowski Bot <autouser@euro-linux.com>

docs/knowledge-base/eurolinux-7-vault.md

@@ -0,0 +1,95 @@
+# Using EuroLinux 7 from vaulted repositories
+
+## EuroLinux 7 EOL 2024-06-30
+
+EuroLinux 7 reached its end of life on 2024-06-30. It means no further updates,
+including security updates, will be available. We strongly recommend upgrading
+to EuroLinux 8 or later as soon as possible. However, you may still need to use
+the older version for development, legacy, and compatibility reasons.
+
+## EuroLinux 7 vault
+
+Using the following gist is a straightforward way to access the EuroLinux 7
+vault:
+
+<script src="https://gist.github.com/AlexBaranowski/4d1aab197164ec55e200c00ceb6884db.js"></script>
+
+
+Or manually add the following files to `/etc/yum.repos.d/eurolinux-7-vault-repos.repo`:
+
+
+```ini
+[eurolinux7-base]
+name=Eurolinux 7 Base Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.9/os/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+
+[eurolinux7-updates]
+name=Eurolinux 7 Updates Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.9/updates/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+```
+
+
+The GPG key should be available in the system, but if it is not, you can add it
+with the following:
+
+
+```bash
+curl -o /etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7 https://fbi.cdn.euro-linux.com/security/RPM-GPG-KEY-eurolinux7
+```
+
+## EuroLinux 7.8 and 7.7
+
+As a bonus, you could also use even older versions of EuroLinux 7.8 and 7.7,
+which contain only updates up to the last minor release of the given version.
+Sample content of the `.repo` files are below:
+
+For EuroLinux 7.8:
+```ini
+[eurolinux7-base]
+name=Eurolinux 7.8 Base Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.8/os/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+
+[eurolinux7-updates]
+name=Eurolinux 7.8 Updates Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.8/updates/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+```
+
+For EuroLinux 7.7:
+```ini
+[eurolinux7-base]
+name=Eurolinux 7.8 Base Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.7/os/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+
+[eurolinux7-updates]
+name=Eurolinux 7.8 Updates Vault
+baseurl=https://vault.cdn.euro-linux.com/legacy/eurolinux/7/7.7/updates/
+gpgcheck=1
+gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-eurolinux7
+```
+
+
+## Removing subscription packages
+
+Since the EuroLinux 7 repositories were behind the paywall, you used to need
+the subscription that used `rhn_register` or `el_register` commands and ancient
+EuroMan service or local mirror of the system. EuroMan was sunsetted with
+EuroLinux 7 EOL.
+
+
+You can confidently remove the subscription-related packages (as long as you
+are not using custom Spacewalk/EuroMan Forman/EuroMan) with the following
+command:
+
+```bash
+sudo yum remove -y rhn* subscription*
+```

docs/knowledge-base/eurolinux-vault-policy.md

@@ -21,7 +21,8 @@ each minor release (minor release is for example EuroLinux 8.6 -> 8.7 -> 8.8),
 of the vault. The first one is the initial state of the release, then there is
 current state (for living release), the third one has '-last' and it's the last
 snapshot before a new minor release. This idea originated from community
-feedback. For example in case of EuroLinux 8.7 (that in time of writing this documentation is the latest minor release):
+feedback. For example in case of EuroLinux 8.7 (that in time of writing this
+documentation is the latest minor release):
 
 - [https://vault.cdn.euro-linux.com/legacy/eurolinux/8/8.7-init/](https://vault.cdn.euro-linux.com/legacy/eurolinux/8/8.7-init/)
   contains the initial state for 8.7
@@ -33,7 +34,7 @@ feedback. For example in case of EuroLinux 8.7 (that in time of writing this doc
   of this minor release.
 
 If there is no version with `-last` suffix it means that this version is a
-newest minor release.
+newest minor release or the `-last` was not created.
 
 ## Vault for the current version