system-config/doc/source/sysadmin.rst

title

System Administration

System Administration

Our infrastructure is code and contributions to it are handled just like the rest of OpenStack. This means that anyone can contribute to the installation and long-running maintenance of systems without shell access, and anyone who is interested can provide feedback and collaborate on code reviews.

The configuration of every system operated by the infrastructure team is managed by a combination of Ansible and Puppet:

https://opendev.org/opendev/system-config

All system configuration should be encoded in that repository so that anyone may propose a change in the running configuration to Gerrit.

Making a Change in Puppet

Many changes to the Puppet configuration can safely be made while only performing syntax checks. Some more complicated changes merit local testing and an interactive development cycle. The system-config repo is structured to facilitate local testing before proposing a change for review. This is accomplished by separating the puppet configuration into several layers with increasing specificity about site configuration higher in the stack.

The modules/ directory holds puppet modules that abstractly describe the configuration of a service. Ideally, these should have no OpenStack-specific information in them, and eventually they should all become modules that are directly consumed from PuppetForge, only existing in the system-config repo during an initial incubation period. This is not yet the case, so you may find OpenStack-specific configuration in these modules, though we are working to reduce it.

The modules/openstack_project/manifests/ directory holds configuration for each of the servers that the OpenStack project runs. Think of these manifests as describing how OpenStack runs a particular service. However, no site-specific configuration such as hostnames or credentials should be included in these files. This is what lets you easily test an OpenStack project manifest on your own server.

Finally, the manifests/site.pp file contains the information that is specific to the actual servers that OpenStack runs. These should be very simple node definitions that largely exist simply to provide private data from hiera to the more robust manifests in the openstack_project modules.

This means that you can run the same configuration on your own server simply by providing a different manifest file instead of site.pp.

Note

The example below is for Debian / Ubuntu systems. If you are using a Red Hat based system be sure to setup sudo or simply run the commands as the root user.

As an example, to run the etherpad configuration on your own server, start by ensuring git is installed and then cloning the system-config Git repo:

sudo su -
apt-get install git
git clone https://opendev.org/opendev/system-config
cd system-config

Then copy the etherpad node definition from manifests/site.pp to a new file (be sure to specify the FQDN of the host you are working with in the node specifier). It might look something like this:

# local.pp
class { 'openstack_project::etherpad':
  ssl_cert_file_contents  => hiera('etherpad_ssl_cert_file_contents'),
  ssl_key_file_contents   => hiera('etherpad_ssl_key_file_contents'),
  ssl_chain_file_contents => hiera('etherpad_ssl_chain_file_contents'),
  mysql_host              => hiera('etherpad_db_host', 'localhost'),
  mysql_user              => hiera('etherpad_db_user', 'username'),
  mysql_password          => hiera('etherpad_db_password'),
}

Note

Be sure not to use any of the hiera functionality from manifests/site.pp since it is not installed yet. You should be able to comment out the logic safely.

Then to apply that configuration, run the following from the root of the system-config repository:

./install_puppet.sh
./install_modules.sh
puppet apply -l /tmp/manifest.log --modulepath=modules:/etc/puppet/modules manifests/local.pp

That should turn the system you are logged into into an etherpad server with the same configuration as that used by the OpenStack project. You can edit the contents of the system-config repo and iterate puppet apply as needed. When you're ready to propose the change for review, you can propose the change with git-review. See the Development workflow section in the Developer's Guide for more information.

Accessing Clouds

As an unprivileged user who is a member of the admin group on bridge, you can access any of the clouds with:

openstack --os-cloud <cloud name> --os-cloud-region <region name>

Adding a New Server

To create a new server, do the following:

• Add a file in :git_file:`modules/openstack_project/manifests/` that defines a class which specifies the configuration of the server.

• Add a node pattern entry in :git_file:`manifests/site.pp` for the server that uses that class. Make sure it supports an ordinal naming pattern (e.g., fooserver01.openstack.org not just fooserver.openstack.org, even if you're replacing an existing server) and that another server with the same does not already exist in the ansible inventory.

• If your server needs private information such as passwords, use hiera calls in the site manifest, and ask an infra-core team member to manually add the private information to hiera.

• You should be able to install and configure most software only with ansible or puppet. Nonetheless, if you need SSH access to the host, add your public key to :git_file:`playbooks/group_vars/all.yaml` and include a stanza like this in your server class:

  extra_users:
    - your_user_name

• Add an RST file with documentation about the server in :git_file:`doc/source` and add it to the index in that directory.

SSH Access

For any of the systems managed by the OpenStack Infrastructure team, the following practices must be observed for SSH access:

• SSH access is only permitted with SSH public/private key authentication.
• Users must use a strong passphrase to protect their private key. A passphrase of several words, at least one of which is not in a dictionary is advised, or a random string of at least 16 characters.
• To mitigate the inconvenience of using a long passphrase, users may want to use an SSH agent so that the passphrase is only requested once per desktop session.
• Users private keys must never be stored anywhere except their own workstation(s). In particular, they must never be stored on any remote server.
• If users need to 'hop' from a server or bastion host to another machine, they must not copy a private key to the intermediate machine (see above). Instead SSH agent forwarding may be used. However due to the potential for a compromised intermediate machine to ask the agent to sign requests without the users knowledge, in this case only an SSH agent that interactively prompts the user each time a signing request (ie, ssh-agent, but not gnome-keyring) is received should be used, and the SSH keys should be added with the confirmation constraint ('ssh-add -c').
• The number of SSH keys that are configured to permit access to OpenStack machines should be kept to a minimum.
• OpenStack Infrastructure machines must use puppet to centrally manage and configure user accounts, and the SSH authorized_keys files from the openstack-infra/system-config repository.
• SSH keys should be periodically rotated (at least once per year). During rotation, a new key can be added to puppet for a time, and then the old one removed. Be sure to run puppet on the backup servers to make sure they are updated.

GitHub Access

To ensure that code review and testing are not bypassed in the public Git repositories, only Gerrit will be permitted to commit code to OpenStack repositories. Because GitHub always allows project administrators to commit code, accounts that have access to manage the GitHub projects necessarily will have commit access to the repositories.

A shared Github administrative account is available (credentials stored in the global authentication location). If administrators would prefer to keep a separate account, it can be added to the organisation after discussion and noting the caveats around elevated access. The account must have 2FA enabled.

In either case, the adminstrator accounts should not be used to check out or commit code for any project.

Note that it is unlikely to be useful to use an account also used for active development, as you will be subscribed to many notifications for all projects.

Root only information

Some information is only relevant if you have root access to the system - e.g. you are an OpenStack CI root operator, or you are running a clone of the OpenStack CI infrastructure for another project.

Force configuration run on a server

If you need to force a configuration run on a single server before the usual cron job time, you can use the kick.sh script on bridge.openstack.org.

You could do a single server:

# /opt/system-config/production/tools/kick.sh 'review.openstack.org'

Or use matching to cover a range of servers:

# /opt/system-config/production/tools/kick.sh 'ze*.openstack.org'

# /opt/system-config/production/tools/kick.sh 'ze0[1-4].openstack.org'

Backups

Infra uses the bup tool for backups.

Hosts in the backup Ansible inventory group will be backed up to servers in the backup-server group with bup. The playbooks/roles/backup and playbooks/roles/backup-server roles implement the required setup.

The backup server has a unique Unix user for each host to be backed up. The roles will setup required users, their home directories in the backup volume and relevant authorized_keys.

Host backup happens via a daily cron job (managed by Ansible) on each individual host to be backed up. The host to be backed up initiates the backup process to the remote backup server(s) using a separate ssh key setup just for backup communication (see /root/.ssh/config).

Restore from Backup

On the server that needs items restored from backup become root, start a screen session as restoring can take a while, and create a working directory to restore the backups into. This allows us to be selective in how we restore content from backups:

sudo su -
screen
mkdir /root/backup-restore-$DATE
cd /root/backup-restore-$DATE

Root uses a separate ssh key and remote user to communicate with the backup server(s); the username and key to use for backup should be automatically configured in /root/.ssh/config. The backup server hostname can be taken from there.

At this point we can join the tar that was split by the backup cron:

bup join -r backup.x.y.opendev.org: root > backup.tar

At this point you may need to wait a while. These backups are stored on servers geographically distant from our normal servers resulting in less network throughput between servers than we are used to.

Once the bup join is complete you will have a tar archive of that backup. It may be useful to list the files in the backup tar -tf backup.tar to get an idea of what things are available. At this point you will probably either want to extract the entire backup:

tar -xvf backup.tar
ls -al

Or selectively extract files:

# path/to/file needs to match the output given by tar -t
tar -xvf backup.tar path/to/file

Note if you created your working directory in a path that is not excluded by bup you will want to remove that directory when your work is done. /root/backup-restore-* is excluded so the path above is safe.

Rotating backup storage

Since bup only stores differences, it does not have an effective way to prune old backups. The easiest way is to simply periodically start the backups fresh.

The backup server keeps an active volume and the previously rotated volume. Each consists of 3 x 1TiB volumes grouped with LVM. The volumes are mounted at /opt/backups-YYYYMM for the date it was created; /opt/backups is a symlink to the latest volume. Periodically we rotate the active volume for a fresh one. Follow this procedure:

1. Create the new volumes via API (on bridge.o.o). Create 3 volumes, named for the server with the year and date added:

   DATE=$(date +%Y%m)
   OS_VOLUME_API_VERSION=1
   OS_CMD="./env/bin/openstack --os-cloud-openstackci-rax --os-region=ORD"
   SERVER="backup01.ord.rax.ci.openstack.org"
   ${CMD} volume create --size 1024 ${SERVER}/main01-${DATE}
   ${CMD} volume create --size 1024 ${SERVER}/main02-${DATE}
   ${CMD} volume create --size 1024 ${SERVER}/main03-${DATE}

2. Attach the volumes to the backup server::

   ${OS_CMD} server add volume ${SERVER} ${SERVER}/main01-${DATE} ${OS_CMD} server add volume ${SERVER} ${SERVER}/main02-${DATE} ${OS_CMD} server add volume ${SERVER} ${SERVER}/main03-${DATE}

3. Now on the backup server, create the new backup LVM volume (get the device names from dmesg when they were attached). For simplicity we create a new volume group for each backup series, and a single logical volume ontop:

   DATE=$(date +%Y%m)
   pvcreate /dev/xvd<DRIVE1> /dev/xvd<DRIVE2> /dev/xvd<DRIVE3>
   vgcreate main-${DATE} /dev/xvdX /dev/xvdY /dev/xvdZ
   lvcreate -l 100%FREE -n backups-${DATE} main-${DATE}
   
   mkfs.ext4 -m 0 -j -L "backups-${DATE}" /dev/main-${DATE}/backups-${DATE}
   tune2fs -i 0 -c 0 /dev/main-${DATE}/backups-${DATE}
   
   mkdir /opt/backups-${DATE}
   # manually add mount details to /etc/fstab
   mount /opt/backups-${DATE}

4. Making sure there are no backups currently running you can now begin to switch the backups (you can stop the ssh service, but be careful not to then drop your connection and lock yourself out; you can always reboot via the API if you do). Firstly, edit /etc/fstab and make the current (soon to be old) backup volume mount read-only. Unmount the old volume and then remount it (now as read-only). This should prevent any accidental removal of the existing backups during the following procedures.

5. Pre-seed the new backup directory (same terminal as above). This will copy all the directories and authentication details (but none of the actual backups) and initalise for fresh backups:

   cd /opt/backups-${DATE}
   rsync -avz --exclude '.bup' /opt/backups/ .
   for dir in bup-*; do su $dir -c "BUP_DIR=/opt/backups-${DATE}/$dir/.bup bup init"; done

6. The /opt/backups symlink can now be switched to the new volume:

   ln -sf /opt/backups-${DATE} /opt/backups

7. ssh can be re-enabled and the new backup volume is effectively active.

8. Now run a test backup from a server manually. Choose one, get the backup command from cron and run it manually in a screen (it might take a while), ensuring everything seems to be writing correctly to the new volume.

9. You can now clean up the oldest backups (the one before the one you just rotated). Remove the mount from fstab, unmount the volume and cleanup the LVM components:

   DATE=<INSERT OLD DATE CODE HERE>
   umount /opt/backups-${DATE}
   lvremove /dev/main-${DATE}/backups-${DATE}
   vgremove main-${DATE}
   # pvremove the volumes; they will have PFree @ 1024.00g as
   # they are now not assigned to anything
   pvremove /dev/xvd<DRIVE1>
   pvremove /dev/xvd<DRIVE2>
   pvremove /dev/xvd<DRIVE3>

10. Remove volumes via API (opposite of adding above with server volume detach then volume delete).

11. Done! Come back and rotate it again next year.

Force-Merging a Change

Occasionally it is necessary to bypass the CI system and merge a change directly. Usually, this is only required if we have a hole in our testing of the CI or related systems themselves and have merged a change which causes them to be unable to operate normally and therefore unable to merge a reversion of the problematic change. In these cases, use the following procedure to force-merge a change.

• Add yourself to the Project Bootstrappers group in Gerrit.
• Navigate to the change which needs to be merged and reload the page.
• Remove any -2 votes on the change.
• Add +2 Code-Review, and +1 Workflow votes if necessary, then add +2 Verified. Also leave a review comment briefly explaining why this was necessary, and make sure to mention it in the #opendev IRC channel (ideally as a #status log entry for the benefit of those not paying close attention to scrollback).
• At this point, a Submit Button should appear, click it. The change should now be merged.
• Remove yourself from Project Bootstrappers

This procedure is the safest way to force-merge a change, ensuring that all of the normal steps that Gerrit performs on repos still happen.

Launching New Servers

New servers are launched using the launch/launch-node.py tool from the git repository https://opendev.org/opendev/system-config. This tool is run from a checkout on the bridge - please see :git_file:`launch/README.rst` for detailed instructions.

Disable/Enable Ansible

You should normally not make manual changes to servers, but instead, make changes through ansible or puppet. However, under some circumstances, you may need to temporarily make a manual change to a managed resource on a server.

OpenDev uses a Static Inventory in Ansible to control execution of Ansible on hosts. A full understanding of the concepts in Ansible Inventory Introduction is essential for being able to make informed decisions about actions to take.

In the case of needing to disable the running of ansible or puppet on a node, it's a simple matter of adding an entry to the ansible inventory "disabled" group in :git_file:`inventory/groups.yaml. The disabled entry is an input to `ansible --list-hosts so you can check your entry simply by running it with ansible $hostlist --list-hosts as root on the bridge host and ensuring that the list of hosts returned is as expected. Globs, group names and server UUIDs should all be acceptable input.

If you need to disable a host immediately without waiting for a patch to land to system-config, there is a file on the bridge host, /etc/ansible/hosts/emergency.yaml that can be edited directly.

/etc/ansible/hosts/emergency.yaml is a file that should normally be empty, but the contents are not managed by ansible. It's purpose is to allow for disabling ansible at times when landing a change to the ansible repo would be either unreasonable or impossible.

Disabling puppet via ansible inventory does not disable puppet from being able to be run directly on the host, it merely prevents ansible from attempting to run it during the regular zuul jobs. If you choose to run puppet manually on a host, take care to ensure that it has not been disabled at the bridge level first.

Examples

To disable an OpenStack instance called amazing.openstack.org temporarily without landing a puppet change, ensure the following is in /etc/ansible/hosts/emergency.yaml

# Please add an inline comment so we know who added the host and why
plugin: yamlgroup
groups:
  disabled:
    - foo.opendev.org # 2020-05-23 bob is testing change 654321

Cinder Volume Management

Adding a New Device

If the main volume group doesn't have enough space for what you want to do, this is how you can add a new volume.

Log into bridge.openstack.org and run:

export OS_CLOUD=openstackci-rax
export OS_REGION_NAME=DFW

openstack server list
openstack volume list

Change the variables to use a different environment. ORD for example:

export OS_CLOUD=openstackci-rax
export OS_REGION_NAME=ORD

• Add a new 1024G cinder volume (substitute the hostname and the next number in series for NN):

  openstack volume create --size 1024 "$HOSTNAME.ord.openstack.org/mainNN"
  openstack server add volume "HOSTNAME.openstack.org" "HOSTNAME.openstack.org/mainNN"

• or to add a 100G SSD volume:

  openstack volume create --type SSD --size 100 "HOSTNAME.openstack.org/mainNN"
  openstack server add volume "HOSTNAME.openstack.org" "HOSTNAME.openstack.org/mainNN"

• Then, on the host, create the partition table:

  DEVICE=/dev/xvdX
  sudo parted $DEVICE mklabel msdos mkpart primary 0% 100% set 1 lvm on
  sudo pvcreate ${DEVICE}1

• It should show up in pvs:

  $ sudo pvs
    PV         VG   Fmt  Attr PSize    PFree
    /dev/xvdX1      lvm2 a-   1024.00g 1024.00g

• Add it to the main volume group:

  sudo vgextend main ${DEVICE}1

• However, if the volume group does not exist yet, you can create it:

  sudo vgcreate main ${DEVICE}1

Creating a New Logical Volume

Make sure there is enough space in the volume group:

$ sudo vgs
  VG   #PV #LV #SN Attr   VSize VFree
  main   4   2   0 wz--n- 2.00t 347.98g

If not, see Adding a New Device.

Create the new logical volume and initialize the filesystem:

NAME=newvolumename
sudo lvcreate -L1500GB -n $NAME main

sudo mkfs.ext4 -m 0 -j -L $NAME /dev/main/$NAME
sudo tune2fs -i 0 -c 0 /dev/main/$NAME

Be sure to add it to /etc/fstab.

Expanding an Existing Logical Volume

Make sure there is enough space in the volume group:

$ sudo vgs
  VG   #PV #LV #SN Attr   VSize VFree
  main   4   2   0 wz--n- 2.00t 347.98g

If not, see Adding a New Device.

The following example increases the size of a volume by 100G:

NAME=volumename
sudo lvextend -L+100G /dev/main/$NAME
sudo resize2fs /dev/main/$NAME

The following example increases the size of a volume to the maximum allowable:

NAME=volumename
sudo lvextend -l +100%FREE /dev/main/$NAME
sudo resize2fs /dev/main/$NAME

Replace an Existing Device

We generally need to do this if our cloud provider is planning maintenance to a volume. We usually get a few days heads up on maintenance window, so depending on the size of the volume, it may take some time to replace.

First thing to do is add the replacement device to the server, see Adding a New Device. Be sure the replacement volume is the same type / size as the existing.

If the step above were followed, you should see something like:

$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree 
  /dev/xvdb1 main lvm2 a--  50.00g     0 
  /dev/xvdc1 main lvm2 a--  50.00g 50.00g

Be sure both devices are in the same VG (volume group), if not you did not properly extend the device.

Note

Be sure to use a screen session for the following step!

Next is to move the data from once device to another:

$ sudo pvmove /dev/xvdb1 /dev/xvdc1
  /dev/xvdb1: Moved: 0.0%
  /dev/xvdb1: Moved: 1.8%
  ...
  ...
  /dev/xvdb1: Moved: 99.4%
  /dev/xvdb1: Moved: 100.0%

Confirm all the data was moved, and the original device is empty (PFree):

$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree 
  /dev/xvdb1 main lvm2 a--  50.00g 50.00g
  /dev/xvdc1 main lvm2 a--  50.00g     0 

And remove the device from the main volume group:

$ sudo vgreduce main /dev/xvdb1
  Removed "/dev/xvdb1" from volume group "main"

To be safe, we can also wipe the label from LVM:

$ sudo pvremove /dev/xvdb1
  Labels on physical volume "/dev/xvdb1" successfully wiped

Leaving us with just a single device:

$ sudo pvs
  PV         VG   Fmt  Attr PSize  PFree
  /dev/xvdc1 main lvm2 a--  50.00g    0 

At this time, you are able to remove the original volume from openstack if no longer needed.

Email

There is a shared email account used for Infrastructure related mail (account sign-ups, support tickets, etc). Root admins should ensure they have access to this account; access credentials are available from any existing member.