Set up Entropy (Randomness) for TeamForge

When Linux needs to create secure resources such as SSH keys, TLS/SSL certificates, password hashes, or secure tokens, it requires random numbers. Entropy is the system's supply of this randomness.

Some TeamForge components especially Gerrit generate keys and certificates during installation or startup. If the server has too little entropy, Linux pauses and waits for randomness, which can cause:

• TeamForge Gerrit (or related services) not starting automatically
• Provisioning scripts taking a very long time or timing out
• Commands that should take seconds taking minutes
• "It looks stuck" behavior during setup

Why Cloud VMs Often Have Low Entropy

Physical servers get randomness from many unpredictable events keyboard/mouse timings, device interrupts, and hardware behavior.

Cloud VMs typically have:

• No keyboard or mouse activity
• Fewer unpredictable hardware events
• Limited access to hardware random devices

As a result, they can run low on entropy, especially during first boot, provisioning, or heavy cryptographic work.

Check Available Entropy

cat /proc/sys/kernel/random/entropy_avail

How to Read the Number

Value	Meaning
1000+	Usually fine
300–1000	May work, but watch for issues
Below 300	Likely to cause delays or hangs during provisioning
0–100	High chance of startup/provisioning failures

This number changes over time. Check it when you see the problem.

Install and Enable rngd (Recommended Fix)

Red Hat recommends using the rngd daemon (from rng-tools) on RHEL-based cloud instances to keep entropy healthy. It runs in the background and feeds the system with randomness from available sources.

Step 1 — Install the Package

RHEL / CentOS / AlmaLinux 8/9:

sudo dnf install -y rng-tools

RHEL / CentOS 7:

sudo yum install -y rng-tools

Step 2 — Enable and Start the Service

sudo systemctl enable --now rngd

Check that it is running:

sudo systemctl status rngd

Step 3 — Verify Entropy Improved

cat /proc/sys/kernel/random/entropy_avail

You should see a higher, more stable number after rngd is active.

Check for a Hardware Random Device (VMs)

Many modern systems expose a hardware random device. If present, rngd can use it as an additional entropy source.

Check if /dev/hwrng exists:

ls -l /dev/hwrng

If /dev/hwrng exists, rngd can use it automatically. If it does not exist, rngd may still help depending on the platform, but results vary by environment.

Quick Copy-Paste Fix

RHEL 8/9, AlmaLinux 8/9:

sudo dnf install -y rng-tools
sudo systemctl enable --now rngd
cat /proc/sys/kernel/random/entropy_avail

RHEL / CentOS 7:

sudo yum install -y rng-tools
sudo systemctl enable --now rngd
cat /proc/sys/kernel/random/entropy_avail

Troubleshooting

If you see a provisioning failure that looks like the system is stuck during key generation or secure startup steps:

1. Check entropy:

   cat /proc/sys/kernel/random/entropy_avail

2. If it is low, install and start rngd (see Install and Enable rngd).
3. Retry the failed provisioning or startup action.

note

• Is this a TeamForge bug? Not exactly. It is an OS/VM environment issue where Linux cannot generate randomness fast enough.
• Is installing rng-tools safe? Yes. This is a common and recommended approach on cloud VMs to avoid entropy starvation.
• Do I need to keep rngd running permanently? Recommended on cloud VMs. It is lightweight and prevents future "randomness waiting" problems.
• Reference: Red Hat guidance on entropy for RHEL-based cloud instances