Subversion Repositories havirt

- **Virtualization**: KVM/QEMU with libvirt installed

- **Perl Modules**:

  - `YAML::Tiny`

- All nodes must be able to SSH to each other (including themselves)

- Consistent hostname resolution across all nodes

- **NFS share** mounted at the **same path** on all nodes

- Recommended: Dedicated NFS share for havirt (minimum 100MB)

- **Nodes**: 4 x Devuan Linux (Chimaera) hypervisors

- **Virtualization**: libvirt/KVM/QEMU

- **Storage**: NAS providing iSCSI targets

- **Lock requirement**: NFS file locking enabled

```bash

# On NFS server

mkdir -p /exports/havirt

```

/exports/havirt  node1(rw,sync,no_subtree_check) node2(rw,sync,no_subtree_check) node3(rw,sync,no_subtree_check)

```bash

exportfs -ra

```

```bash

# Create mount point

echo "nfs-server:/exports/havirt  /media/shared  nfs  defaults  0  0" >> /etc/fstab

mount /media/shared

# Verify

```

```bash

apt update

```

**RHEL/CentOS/Rocky:**

```bash

yum install -y libvirt qemu-kvm perl-Data-Dumper perl-YAML-Tiny subversion

```

Verify Perl modules:

```bash

perl -MData::Dumper -e 'print "Data::Dumper OK\n"'

perl -MYAML::Tiny -e 'print "YAML::Tiny OK\n"'

```

### Step 4: Install havirt

Install havirt to the NFS share (run on any node):

```bash

# Check out stable version

svn co http://svn.dailydata.net/svn/havirt/stable /media/shared/havirt

# Verify installation

ls -la /media/shared/havirt/

```

You should see:

```

havirt              # Main executable

*.pm                # Module files

config.sample.yaml  # Sample configuration

conf/               # Directory for VM configs

var/                # Directory for state files

```

### Step 5: Create Symlinks on All Nodes

On each node:

```bash

ln -s /media/shared/havirt/havirt /usr/local/bin/havirt

# Verify

which havirt

havirt --version

```

### Step 6: Generate Initial Configuration

On any node:

```bash

cd /media/shared/havirt

havirt

```

This creates `config.yaml` with safe defaults. By default, havirt runs in **dry-run mode** (commands are displayed but not executed).

Review and customize:

```bash

vi config.yaml

```

Key settings to review:

```yaml

flags:

  dryrun: 1                    # Keep at 1 until setup complete

  verbose: 1                   # Show detailed output

  debug: 0                     # Set to 1-3 for troubleshooting

node reserved memory: 8388608  # 8GB reserved per node (adjust as needed)

min scan time: 300             # Minimum 5 minutes between scans

```

### Step 7: Configure SSH Keys

All nodes must authenticate to each other without passwords.

**On each node, as root:**

```bash

# Generate SSH key (if not already present)

if [ ! -f /root/.ssh/id_rsa ]; then

    ssh-keygen -t rsa -b 4096 -N "" -f /root/.ssh/id_rsa

fi

# Append public key to shared collection

cat /root/.ssh/id_rsa.pub >> /media/shared/havirt/sshkeys

```

**After all nodes have added their keys:**

```bash

# On each node, deploy the collected keys

cat /media/shared/havirt/sshkeys >> /root/.ssh/authorized_keys

chown root:root /root/.ssh/authorized_keys

chmod 600 /root/.ssh/authorized_keys

```

**Test SSH connectivity from each node:**

```bash

# On node1, test connectivity to all nodes

for node in node1 node2 node3 node4; do

    echo "Testing $node..."

    ssh -o StrictHostKeyChecking=accept-new $node hostname

done

```

**Optional**: Create SSH config for convenience:

```bash

cat > /root/.ssh/config << 'EOF'

Host node1

    HostName node1.example.com

    User root

Host node2

    HostName node2.example.com

    User root

# Add entries for all nodes

EOF

chmod 600 /root/.ssh/config

```

### Step 8: Register Nodes

Register each hypervisor node in the cluster database.

**On any node:**

```bash

# Add each node

havirt node add node1

havirt node add node2

havirt node add node3

havirt node add node4

# Verify all nodes registered

havirt node list

```

Expected output:

```

     name     memory  cpu_count maintenance

    node1  67108864         16           0

    node2  67108864         16           0

    node3  67108864         16           0

```

For TSV output (useful for scripts):

```bash

havirt --format tsv node list

```

### Step 9: Configure iSCSI (Optional)

If using iSCSI shared storage, configure targets:

```bash

# Add iSCSI target to configuration

havirt cluster iscsi add 192.168.1.10

# Verify target added

havirt cluster iscsi

# Test on one node first

havirt cluster iscsi update node1

# If successful, update all nodes

havirt cluster iscsi update

# Verify iSCSI sessions

iscsiadm -m session

```

### Step 10: Import Existing VMs

Discover and register VMs already running on the cluster.

```bash

# Scan all nodes for running VMs

havirt node scan --force

# Import VM configurations

havirt domain update

# List all discovered VMs

havirt domain list

```

Expected output:

```

         name   memory vcpu  node maintenance

      webvm1  4194304    4 node1           0

       db01   8388608    8 node2           0

   testvm    2097152    2 node3           0

```

### Step 11: Enable Automated Scanning

Set up cron job to keep cluster database current:

```bash

# Copy sample cron file

# Edit if needed

vi /etc/cron.d/havirt

```

Default cron content:

```bash

*/5 * * * * root /usr/local/bin/havirt node scan --quiet 2>&1 | logger -t havirt

```

Verify cron job:

```bash

systemctl restart cron

tail -f /var/log/syslog | grep havirt

```

### Step 12: Enable Production Mode

Once testing is complete, enable command execution:

```bash

# Edit configuration

vi /media/shared/havirt/config.yaml

```

Change:

```yaml

flags:

  dryrun: 0  # Changed from 1 to 0 if desired

```

**Test with a safe operation:**

```bash

# This should now actually execute

havirt node scan

havirt domain list

```

## Post-Installation

### Verify Installation

Run through this checklist:

```bash

# 1. Check NFS mount on all nodes

for node in node1 node2 node3; do

    ssh $node "df -h | grep shared"

done

# 2. Verify SSH connectivity

for node in node1 node2 node3; do

    ssh $node hostname

done

# 3. Check node registration

havirt node list

# 4. Verify VM discovery

havirt domain list

# 5. Check cluster statistics

havirt cluster stats

# 6. Test dry-run vs real execution

havirt --dryrun 1 domain list  # Shows command

havirt --dryrun 0 domain list  # Executes command

```

### Test Migration

Test VM migration between nodes:

```bash

# List VMs and their locations

havirt domain list

# In dry-run mode, test migration command

havirt --dryrun 1 domain migrate testvmname node2

# If output looks correct, execute

havirt --dryrun 0 domain migrate testvmname node2

# Verify migration

havirt node scan --force

havirt domain list

```

### Configure Logging (Recommended)

Set up dedicated logging:

```bash

# Create log directory

mkdir -p /var/log/havirt

# Add to rsyslog

cat > /etc/rsyslog.d/havirt.conf << 'EOF'

if $programname == 'havirt' then /var/log/havirt/havirt.log

& stop

EOF

# Restart rsyslog

systemctl restart rsyslog

# Add logrotate

cat > /etc/logrotate.d/havirt << 'EOF'

/var/log/havirt/*.log {

    daily

    rotate 30

    compress

    delaycompress

    notifempty

    create 640 root root

}

EOF

```

## Troubleshooting

### NFS Issues

**Problem**: "Permission denied" accessing `/media/shared/havirt`

```bash

# Check NFS mount

mount | grep shared

# Check permissions

ls -la /media/shared

# Test write access

touch /media/shared/test && rm /media/shared/test

# Check NFS server exports

showmount -e nfs-server

```

**Problem**: Lock file issues

```bash

# Remove stale lock

rm -f /media/shared/havirt/var/status.yaml.lock

# Verify NFS locking enabled on server

```

### SSH Connectivity Issues

**Problem**: "Permission denied (publickey)"

```bash

# Verify key in authorized_keys

cat /root/.ssh/authorized_keys

# Check SSH key permissions

chmod 700 /root/.ssh

chmod 600 /root/.ssh/id_rsa

chmod 644 /root/.ssh/id_rsa.pub

chmod 600 /root/.ssh/authorized_keys

# Test with verbose output

ssh -v node2

```

### Module Installation Issues

**Problem**: "Can't locate YAML/Tiny.pm"

```bash

# Debian/Ubuntu

apt install libyaml-tiny-perl

# RHEL/CentOS

yum install perl-YAML-Tiny

# Or use CPAN

cpan YAML::Tiny

```

### VM Not Found

**Problem**: havirt can't find running VM

```bash

# Force rescan

havirt node scan --force

# Check if VM actually running

virsh list --all

# Update VM database

havirt domain update vmname

# Check status database

cat /media/shared/havirt/var/status.yaml | grep vmname

```

### Debug Mode

Enable verbose debugging:

```bash

# Debug level 1: Basic info

havirt --debug 1 node scan

# Debug level 2: Detailed info

havirt --debug 2 domain list

# Debug level 3: Full command trace

havirt --debug 3 cluster stats

```

## Upgrading

To upgrade to a newer version:

```bash

cd /media/shared/havirt

# Backup current version

cp -a /media/shared/havirt /media/shared/havirt.backup

# Update from repository

svn update

# Check version

havirt --version

# Review changes

cat CHANGES.md

# Test with dry-run

havirt --dryrun 1 node scan

```

## Uninstallation

To remove havirt:

```bash

# Remove cron job

rm /etc/cron.d/havirt

# Remove symlink from all nodes

rm /usr/local/bin/havirt

# Remove installation (from NFS)

rm -rf /media/shared/havirt

# Unmount NFS if no longer needed

umount /media/shared

```

## Next Steps

After installation:

1. Review [USAGE.md](USAGE.md) for detailed command reference

2. Review [README.md](README.md) for operational guidelines

3. Set up monitoring/alerting for cluster health

4. Document your VM migration procedures

5. Test maintenance mode workflow

6. Test cluster balancing in dry-run mode

## Getting Help

- Check [USAGE.md](USAGE.md) for command syntax

- Review [README.md](README.md) for common tasks

- Enable `--debug 3` for detailed troubleshooting

- Check `/var/log/syslog` for cron job output

- Review `/media/shared/havirt/var/status.yaml` for cluster state