CentOS Stream Server Administration Guide

This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.

Where CentOS Stream sits

CentOS Stream sits ahead of RHEL. It is where the next RHEL minor content appears first. It is not CentOS Linux 7 or 8, which were rebuilds that trailed RHEL and which are not this install. If you wanted a frozen rebuild, Rocky or Alma are the other pillars. If you wanted a paid product, RHEL is the other pillar.

The commands still look like the family: dnf, NetworkManager, firewalld, SELinux enforcing, systemd. The difference is the cadence. A Stream host will change under you more often. That is acceptable only if someone will read those updates. It is a poor surprise for a server nobody wants to touch.

Lab hostname edge-01, address 192.0.2.10/24 via 192.0.2.1, named admin, key. Replace the address in production. Do not add a RHEL entitlement repo and a Stream repo and call it more secure.

Write Stream in the inventory in large letters. The next person who pastes a CentOS Linux 7 command will otherwise think the host is merely old.

The first hour on a lab host

Step 1 on CentOS Stream covers identity. os-release must say Stream. Write that word in the inventory. Everything else in the family is a different promise. The check is: The ticket says CentOS Stream and the version. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for CentOS Stream draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 2 on CentOS Stream covers admin. Named user, key, sudo. Same hardening order. The check is: Key login works. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for CentOS Stream draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 3 on CentOS Stream covers network. nmcli and firewalld for the lab prefix. A CentOS 7 network script is the wrong era. The check is: The address matches after a reboot. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for CentOS Stream draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 4 on CentOS Stream covers SELinux. Enforcing. Stream does not get a weaker mode because it moves quickly. The check is: getenforce is Enforcing. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for CentOS Stream draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 5 on CentOS Stream covers updates. Apply Stream updates on a canary before a fleet. A fleet of Stream hosts with no reader of updates is an accident. The check is: The canary's version is recorded. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for CentOS Stream draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

# CentOS Stream lab. Review before you paste.
# This is Stream, not CentOS Linux and not Rocky.
# dnf, firewalld, SELinux Enforcing.
# Lab address 192.0.2.10/24 via 192.0.2.1.
# prompt-for-this is not a password to keep.

The commands you will actually repeat

dnf update is a regular event, not an annual one. Use the patch guide's canary. Reboot when kernels arrive.

firewalld and SELinux stay as on RHEL. Enforcing. Management prefix only.

When a package behaves differently from last month's RHEL note, believe the host and read the Stream change, rather than pinning a random older RPM.

Plan the day you will leave Stream if the organisation actually wanted a rebuild. That plan is the migration guide, started before the host is critical.

What CentOS Stream is not

Stream is not CentOS Linux. Old blog posts for CentOS 7 are not instructions.

It is not a bug-for-bug rebuild. Do not promise application vendors a RHEL minor version you do not have.

It is not Fedora, though Fedora is further upstream. The Fedora pillar is the short-lifecycle one.

The hour you stop

Write the hostname, the role, and the clock time before you change CentOS Stream. If this host is also serving users, it is not the lab and this first hour belongs on a spare. The provisioning guide is how the spare gets built. A change without a spare is a change you can still postpone.

Keep the console or the out-of-band path open for the whole hour. Reloading a network service, a firewall, or a secure-shell daemon from the only session is how a lab becomes a drive across town. The hardware guide names that path for a physical machine. A virtual machine uses the hypervisor console. A cloud instance uses the serial console the platform gives you. Test it before the reload, not after.

The address 192.0.2.10/24 and the gateway 192.0.2.1 are documentation. They belong in the lab note and nowhere else. On a real network, use the prefix the network desk already assigned. On a cloud instance, use the address the platform assigned and do not hard-code the documentation range into user-data. If a generator filled the documentation address into a production draft, delete it.

prompt-for-this is a reminder that a secret is missing. It is not a password you set, not a token you commit, and not a string you leave in a configuration file because the service started. The real secret lives in the password store. The ticket says who can read it. A file that still contains the reminder is a file you have not finished.

One service is enough for the first hour on CentOS Stream. The purpose from the fundamentals page says which service. Every other package stays uninstalled until its own guide has a ticket. A host that enables a web server, a database, and a queue in the first hour has three changes and no proof. Finish the login, the address, and the update. Then stop.

Read the package transaction before you accept it. A count of packages is not a review. If the list contains a repository you did not add, stop. If it contains a kernel, the patch guide's reboot decision applies and the console stays open. If it contains software this role does not need, remove that line from the plan rather than installing it and disabling it later.

The previous image, the previous configuration file, or the previous package version is the rollback. Write the path down while the host still works. A rollback you invent after a failed reload is a guess. The migration guide assumes the old copy is still there. Do not delete it in the same hour to free a disk.

When the checks pass, copy the notes into the ticket and leave the host alone. The next host waits until a second person can repeat the login and the address from the notes. A fleet built from memory drifts. A fleet built from the file the provisioning guide stored stays boring, which is the point of CentOS Stream in production.

If a step on CentOS Stream fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a host nobody can rebuild. Rebuild from the image instead. The time you lose is smaller than the time you will spend explaining the hybrid.

Hand the finished lab to the guide that matches the role: web, mail, storage, backup, or hardening. CentOS Stream being installed is not the same as the role being ready. The role guide has its own proof. Do not skip it because the package manager exited without an error.

A second person reads the hostname, the address, and the rollback path aloud before you build the next host. If they cannot find those three in the ticket, the notes are not done. Silence is not agreement. The check is the sentence they repeat back.

Store the working notes next to the image version. A month from now CentOS Stream will still boot from that pair, and the chat where you remembered a flag will be gone. The file is the memory. The host is replaceable. That is the whole point of writing this hour down.

CentOS Stream checks before a second host

Confirm this before you call the change done: CentOS Stream is the OS the hostname reports, not a neighbour you copied from. The lab address 192.0.2.10/24 is gone before this host is placed on a real network. prompt-for-this is not the password that was set, and no password is in the ticket. The named admin can log in with a key. The package manager used is the one this page names. A network file from a different distribution was not pasted in. The config test or the apply command for this network tool succeeded. The previous image or install file is kept. No new third-party repository was added in the first hour. A service you do not need was not enabled to see what it does. Console or out-of-band access works before you reload SSH. A second person read the hostname and the address. The inventory says Stream, not CentOS Linux. No rebuild mirror was added to make it freeze. Someone is named to read Stream updates. And SELinux is Enforcing. If one of those fails, stop.

Tools for this guide

These tools run in the browser on this site. They do not log into your machines.

Guides in this cluster

These supporting pages belong to this pillar.