Last checked and updated on 09 Jun 2026
What Is New in Docker Engine 1.2
Docker Engine 1.2 delivers critical stability improvements, new container management commands, and enhanced networking capabilities. This release focuses on making the developer experience smoother and the platform more robust for production workloads.
| Category | Key Changes |
|---|---|
| New Features | New docker pause and docker unpause commands |
| Improvements | Enhanced docker ps formatting, improved container linking |
| Bug Fixes | Fixes for AUFS, device mapper, and HTTP proxy configuration |
| Security | Updated libcontainer and TLS enhancements |
| Deprecations | Deprecated lxc execution driver |
What are the new container control commands?
The standout addition is the docker pause and docker unpause command pair. This gives you fine-grained control over a running container's processes by freezing them without terminating the container itself.
In practice, this is perfect for troubleshooting or temporarily halting a process to inspect its state. It uses the underlying cgroups freezer to suspend all processes, which is much cleaner than sending signals.
You use it just like any other lifecycle command: docker pause <container> and docker unpause <container>. This finally provides a native way to halt a container without needing to stop or kill it.
How was the developer experience improved?
Several quality-of-life tweaks make daily container management less tedious. The docker ps command received formatting improvements, making its output easier to read and parse at a glance.
Container linking was also made more reliable. This matters because linking is a fundamental way to establish communication between containers before user-defined networks became the standard.
Under the hood, numerous bugs were squashed. Key areas included AUFS and device mapper storage drivers, which resolved many edge cases that could cause headaches during intense development cycles.
What security and networking updates were included?
The libcontainer execution layer was updated, bringing various stability and security improvements to the core container runtime. TLS communication for the Docker daemon was also enhanced for more secure client-daemon interactions.
While not a massive networking overhaul, the fixes and underlying updates paved the way for a more stable foundation. This release solidified the core networking stack that future versions would build upon.
A significant shift was the formal deprecation of the lxc execution driver. The message was clear: the native libcontainer driver is the present and future, simplifying the stack and reducing attack surface.
FAQ
What does the new `docker pause` command actually do?
It freezes all processes inside a specified running container using cgroups. The container's state remains in memory but processes won't execute until you use docker unpause.
Is the LXC execution driver still available in 1.2?
Yes, but it's officially deprecated. You can still use it by starting the daemon with --exec-driver=lxc, but switching to the native driver is strongly recommended.
Were there any changes to how Docker handles HTTP proxies?
Yes, several bugs related to HTTP proxy configuration were fixed. This made it more reliable for containers to access the internet through a proxy in corporate environments.
Does this release improve stability on AUFS filesystems?
Absolutely. Multiple bugs specific to the AUFS storage driver were resolved, making it a more reliable choice for development and production on supported systems.
Why is the formatting of `docker ps` output considered an improvement?
The output was made more consistent and easier to read. For developers running docker ps constantly, this small change reduced visual noise and made finding container information faster.