How to fix Out of Shared Memory in Terraform

Connect to your PostgreSQL database and verify current settings:

SHOW shared_buffers;
SHOW max_locks_per_transaction;
SHOW dynamic_shared_memory_type;

For Terraform Enterprise, access the PostgreSQL container logs to identify the exact exhaustion point.

Edit the postgresql.conf file (typically in the PostgreSQL data directory) and increase shared_buffers:

shared_buffers = 512MB

For very high-load environments, consider 1024MB or higher. The rule of thumb is 25% of available system RAM, but PostgreSQL automatically adjusts if you specify too much.

For Terraform Enterprise on mounted disk, copy postgresql.conf from the container to the host mounted disk path and create a bind mount.

In the same postgresql.conf file, increase max_locks_per_transaction:

max_locks_per_transaction = 512

This determines how many locks each transaction can hold. High-concurrency environments may need 1024 or more.

If running Terraform Enterprise in Docker, increase the /dev/shm allocation in your docker-compose.yml:

services:
  tfe:
    shm_size: '1gb'

Restart the container after this change. This ensures dynamic_shared_memory_type = posix has sufficient space.

Check and increase kernel limits if PostgreSQL still fails:

cat /proc/sys/kernel/shmmax
cat /proc/sys/kernel/shmall

To increase permanently, edit /etc/sysctl.conf:

kernel.shmmax = 17179869184
kernel.shmall = 4194304

Apply changes:

sudo sysctl -p

After configuration changes, restart PostgreSQL (or the entire TFE container):

# For standalone PostgreSQL
sudo systemctl restart postgresql

# For Docker container
docker-compose restart tfe

Monitor the PostgreSQL logs to ensure no errors appear:

tail -f /var/log/postgresql/postgresql.log

Run a terraform plan or apply to verify the issue is resolved:

terraform plan

The operation should complete without shared memory errors. Monitor system memory and PostgreSQL logs during execution to ensure stability.