Deep Dive: Why Podman and containerd 2.0 are Replacing Docker in 2026

The containerization landscape, perennially dynamic, has seen a flurry of practical, sturdy advancements over late 2024 and through 2025. As senior developers, we're past the "hype cycle" and into the trenches, evaluating features that deliver tangible operational benefits and address real-world constraints. While Docker remains the undisputed behemoth, its architectural choices—specifically the pervasive daemon—continue to prompt a search for alternatives that prioritize security, system integration, and a more granular control over the container lifecycle. This shift mirrors broader industry trends, such as the move toward specialized runtimes discussed in Cloudflare vs. Deno: The Truth About Edge Computing in 2025.

Let's dissect the recent developments in Podman, Buildah, and containerd, stripping away the marketing fluff to expose what truly works, what's still clunky, and what trade-offs you'll inevitably face in this ever-shifting ecosystem as of early 2026.

The Daemonless Doctrine: Podman's Evolving Architecture

Podman's primary allure has always been its daemonless architecture, a stark contrast to Docker's client-server model. The marketing touts "daemonless means more secure," but the reality is more nuanced; it fundamentally alters how containers integrate with the host OS.

Shedding the Daemon: A Double-Edged Sword

Podman eschews a central, privileged daemon (like dockerd), instead running containers as child processes of the user who invokes the podman command. This architectural choice indeed eliminates a single point of failure and removes the inherent security risk of a long-running, root-privileged daemon. If the podman process is compromised, the blast radius is theoretically contained to the invoking user's privileges.

However, this "daemonless" advantage isn't without its operational quirks. Managing container lifecycles in the background, persistent logging, and automatic restarts traditionally handled by a daemon now require alternative mechanisms. Podman addresses this through deep integration with systemd on Linux systems. For instance, you can generate systemd unit files for individual containers or entire pods using podman generate systemd. This allows containers to be managed like any other system service, leveraging systemd's robust process supervision capabilities. While this approach offers excellent native integration, it shifts complexity from a single daemon to managing multiple systemd units, potentially increasing operational overhead for those unfamiliar with systemd internals. The Podman Desktop application, which became a CNCF Sandbox Project in November 2024 and saw several releases throughout 2025, aims to abstract some of this complexity for developers on macOS and Windows by running Podman in a VM.

# Example: Generate a systemd unit for a simple Nginx container
podman run -d --name my-nginx -p 8080:80 nginx:latest
podman generate systemd --name my-nginx > ~/.config/systemd/user/container-my-nginx.service

# To enable and start it (as a user service)
systemctl --user enable container-my-nginx.service
systemctl --user start container-my-nginx.service

This systemd integration is a practical, sturdy solution for production deployments on Linux, but it demands familiarity with a different paradigm than docker-compose up -d.

Rootless Reality: More Than Just a Flag

Podman's standout feature, rootless containers, reached significant maturity throughout 2024 and 2025. This capability allows unprivileged users to build, run, and manage containers without requiring sudo access, drastically reducing the attack surface. The magic behind rootless operation lies in Linux user namespaces.

When a rootless container is launched, its internal root user (UID 0) is mapped to an unprivileged user ID on the host system, typically within a range defined in /etc/subuid and /etc/subgid. Storage for rootless containers often relies on fuse-overlayfs, a FUSE-based implementation of the overlayfs filesystem. This allows unprivileged users to create and manage layered filesystems, a task typically restricted to the kernel's overlayfs driver. While fuse-overlayfs enables functionality, it generally comes with a performance penalty compared to the kernel module.

Networking for rootless containers is handled by slirp4netns, a user-mode networking stack that creates a virtual network interface and routes traffic through the host's network namespace. This provides network connectivity without requiring elevated privileges or direct manipulation of host network interfaces. However, slirp4netns often exhibits higher latency and lower throughput than CNI-based networking used by rootful containers, making it less ideal for high-performance network-bound workloads. Podman Desktop in its v1.22 release (October 2025) introduced the ability to switch Podman machines between rootless and rootful modes on macOS and Windows, acknowledging the need for flexibility.

Recent Developments: Podman has maintained a brisk release cadence, moving to a timed quarterly release schedule starting with Podman 5.3 in November 2024. This aims for predictable updates, with Podman 5.x releases throughout 2025 bringing performance improvements, better Docker API compatibility in its RESTful service, and ongoing enhancements to Podman Desktop, including a native ARM64 installer for Windows and improved network management UIs. The project is also working on composefs integration and improved BuildKit API support for future releases.

Building Blocks: Buildah's Granular Image Crafting

Buildah is often overshadowed by Podman, but it's the unsung hero for those who demand fine-grained control over their container image creation. It's not just a docker build replacement; it's a daemonless toolkit for OCI image construction.

The Image Assembly Line, Unchained

Buildah provides a set of commands that allow developers to construct OCI-compliant container images step-by-step, without needing a container daemon. While buildah bud offers a Dockerfile-compatible experience (e.g., buildah bud -t myimage .), its true power lies in its atomic commands like buildah from, buildah mount, buildah run, and buildah commit.

This granular control enables advanced image optimization strategies. Instead of relying solely on multi-stage Dockerfiles, you can explicitly mount a container's filesystem (buildah mount), make changes directly using host tools, and then commit only the necessary layers (buildah commit). This "build-from-scratch" or "mount-and-modify" approach helps create extremely minimal images by excluding build-time dependencies and tools (like gcc or package managers) from the final runtime image, significantly reducing image size and attack surface.

# Example: Building a minimal Nginx image with Buildah granular commands
# 1. Start from scratch
container=$(buildah from scratch)

# 2. Add an OS base (e.g., busybox)
buildah add $container busybox.tar /

# 3. Install Nginx (this is simplified, typically you'd copy a pre-built binary)
#    In a real scenario, you might start from a build image, install, then copy.
buildah run $container -- apk add nginx

# 4. Expose port and set entrypoint (Buildah config)
buildah config --port 80 --entrypoint '["nginx", "-g", "daemon off;"]' $container

# 5. Commit to a new image
buildah commit $container my-minimal-nginx:latest

This method, while powerful, requires a deeper understanding of image layering and filesystem operations than a simple Dockerfile. The learning curve is undeniable.

Supply Chain Fortification: SBOM and Beyond

Recent Buildah releases have focused heavily on supply chain security. Buildah 1.35 (March 2024) introduced the crucial --sbom flag, allowing users to generate a Software Bill of Materials (SBOM) during the build or commit process. An SBOM provides a detailed inventory of all components, libraries, and dependencies within a container image, which is essential for identifying vulnerabilities and ensuring compliance.

# Example: Build an image and generate an SBOM
buildah bud --sbom --format spdx -t my-app:latest .

The --sbom flag is a welcome addition, addressing a critical need for transparency in the software supply chain. However, generating an SBOM is merely the first step; its true utility depends on robust tooling for consuming, analyzing, and acting upon this data. Without a comprehensive ecosystem for SBOM management, it risks becoming another checkbox feature rather than a genuine security enhancement. The buildah push command also saw enhancements in 1.35 with --retry and --retry-delay flags for more robust image pushing, acknowledging the flaky nature of network operations to registries.

Recent Developments: Buildah has seen continuous development, with versions from 1.35.0 (March 2024) up to 1.42.0 (October 2025) released. Notable changes include the --pull flag now emulating Docker's --pull=always behavior, and improved handling of destination paths ending with /. These are practical, quality-of-life improvements that streamline workflows, though they highlight the ongoing effort to align with entrenched Docker behaviors.

containerd 2.0: The Unseen Foundation's Hardening

While Podman and Buildah cater to the developer experience, containerd operates at a lower level, acting as the industry-standard core container runtime for Kubernetes and other orchestration systems. Its 2.0 release in late 2024 and subsequent 2.1 in May 2025 are significant milestones, focusing on stability, extensibility, and security.

CRI-O's Backbone, Re-engineered

containerd serves as a high-level container runtime that manages the complete container lifecycle—image transfer, storage, and execution—and exposes a gRPC API. It's the de facto standard for Kubernetes, implementing the Container Runtime Interface (CRI) required by the kubelet. The containerd 2.0 release, seven years after its 1.0 debut, isn't about flashy new end-user features but rather a strategic stabilization and enhancement of core capabilities.

This release consolidates experimental features from the 1.7 series into the stable channel and removes deprecated functionalities, ensuring a more robust and predictable foundation. For production operators, this means a more resilient and performant runtime, though vigilance against API deprecations and removals in Kubernetes versions tied to containerd upgrades remains a critical task. The configuration format also changed to v3, requiring a migration step for existing installations (containerd config migrate).

NRI and User Namespaces: Finer Control, Deeper Security?

containerd 2.0 enables the Node Resource Interface (NRI) by default, providing a powerful extension mechanism for customizing low-level container configurations. NRI allows for finer-grained control over resource allocation and policy enforcement through plugins, akin to mutating admission webhooks but operating directly at the runtime level. This could allow for dynamic injection of runtime configurations or custom resource management policies, a capability previously more cumbersome without direct runtime modifications. While powerful, NRI's true impact will depend on the community developing useful plugins; out-of-the-box, it's a mechanism, not a solution.

Another significant advancement is the improved support for User Namespaces. This feature allows containers to run as root inside the container but map to an unprivileged User ID (UID) on the host system, drastically reducing the blast radius of a container escape. While containerd 2.0 ships with this support, it was still considered "beta for Kubernetes" as of late 2024. This indicates that while the underlying runtime capability is there, its full, stable integration and validation within the complex Kubernetes ecosystem is a longer journey. Enabling it often requires kernel parameters like user.max_user_namespaces=1048576.

Networking Reimagined: CNI, Netavark, and the Rootless Conundrum

Container networking is arguably one of the most complex domains, and the ecosystem continues to evolve, pushing towards more flexible and secure models.

The CNI Standard: A Double-Edged Specification

The Container Network Interface (CNI) remains the foundational specification for configuring network interfaces for Linux containers. Both Podman (when running rootful) and containerd adhere to CNI, ensuring a standardized mechanism for network plugin integration. This means that the underlying network topology (e.g., veth pairs, virtual bridges) for rootful containers is largely consistent across CNI-compliant runtimes.

However, CNI's flexibility, while a strength, can also be a weakness. Different CNI plugins (e.g., Bridge, Host-local, or more advanced ones like Calico, Cilium) offer varying features and complexities. Debugging network issues often requires understanding the specific plugin configuration files, typically located in /etc/cni/net.d/, and the interaction with host-level networking tools like iptables or nftables. This isn't a "set and forget" situation; it demands hands-on network troubleshooting skills.

Podman's Network Shift: From CNI to Netavark

A significant development for Podman users is the transition from CNI to Netavark as the default network backend. Introduced in Podman 4.0, Netavark is a new network stack written in Go, specifically designed to better integrate with Podman's daemonless architecture. CNI is now deprecated and will be removed in a future major Podman version (5.0+), preferring Netavark.

This shift aims to provide a more cohesive networking experience, especially for managing custom networks and DNS resolution. To check which backend your Podman installation uses, you can run podman info --format {{.Host.NetworkBackend}}. While Netavark promises a more robust and integrated solution, it also means that existing CNI configurations, particularly custom ones, might require re-evaluation and migration when upgrading Podman versions.

For rootless containers, slirp4netns remains the primary networking mechanism due to the inherent restrictions on unprivileged users manipulating network devices. This creates a persistent disparity in networking capabilities and performance between rootful and rootless deployments, a fundamental trade-off that developers must actively manage. While slirp4netns is functional, its overhead can be significant for applications demanding high network I/O or low latency.

Security Posture: Beyond Basic Isolation

The container security landscape continues to mature, moving beyond basic image scanning to focus on deeper runtime protections and supply chain integrity.

Layered Defenses: Rootless, Namespaces, and Capabilities

The emphasis on running containers with the least necessary privileges has intensified. Podman's rootless mode and containerd 2.0's improved user namespace support are prime examples of this trend. By mapping container root to an unprivileged host user, the impact of a container escape is significantly mitigated.

Beyond user namespaces, limiting Linux capabilities remains a critical practice. Containers often run with a broad set of default capabilities (e.g., CAP_NET_ADMIN, CAP_SYS_ADMIN) that are rarely needed by most applications. Explicitly dropping unnecessary capabilities (e.g., podman run --cap-drop ALL --cap-add CHOWN myimage) reduces the attack surface. Furthermore, robust integration with host security modules like SELinux and AppArmor provides an additional layer of mandatory access control, confining container processes and restricting their interactions with the kernel. Configuring these, however, is a non-trivial exercise often requiring deep OS-level expertise.

Supply Chain Integrity: SBOMs and Image Verification

The focus on software supply chain security has become paramount. Buildah's --sbom flag, as discussed, is a direct response to this need. Complementing this, the Open Container Initiative (OCI) Image Specification v1.1 (released February 2024) introduced new features like subject and artifactType fields, along with a referrers API, specifically designed to associate metadata artifacts (such as signatures, attestations, and SBOMs) with existing OCI images.

This means that instead of embedding security metadata within the image, which can complicate immutability, external artifacts can now be linked to an image in a standardized way. This is a crucial step towards verifiable image integrity across the supply chain. However, the efficacy of this heavily relies on widespread adoption by registries and tooling. The OCI spec is there, but the operational reality of consistent signing, verification, and enforcement across diverse CI/CD pipelines is still a significant challenge. Many organizations are still grappling with basic image scanning, let alone advanced attestation schemes.

OCI Specifications: The Unsung Architects of Interoperability

While often unseen by the average developer, the Open Container Initiative (OCI) specifications are the bedrock of container interoperability. Their recent updates, particularly in 2024, solidify the foundation upon which Docker alternatives operate.

OCI Image and Distribution Spec v1.1: The Artifacts Era

The OCI Image Specification and Distribution Specification each saw v1.1 releases on February 15, 2024. These were the first minor releases since 2017 and 2021, respectively, and brought significant changes, most notably "Artifacts." The new subject and artifactType fields, coupled with a referrers API, standardize how metadata like signatures, attestations, and SBOMs can be associated with container images.

This is a critical architectural improvement. Previously, attaching such metadata often involved proprietary mechanisms or embedding it in image labels, which lacked a consistent, verifiable standard. The referrers API allows tools to query a registry for all artifacts associated with a given image manifest, enabling a more robust and standardized approach to supply chain security and compliance. Furthermore, v1.1 deprecated the creation of non-distributable layers, simplifying registry operations and improving air-gapped network support. These changes are fundamental, yet their full impact will only be realized as tooling and registries universally adopt the new API.

OCI Runtime Spec v1.2: Beneath the Surface

The OCI Runtime Spec v1.2.0 was released on February 18, 2024. This specification defines the behavior and configuration interface for low-level container runtimes like runc and crun. The v1.2 release included enhancements like support for idmap and ridmap mount options. These options are crucial for enabling more flexible and secure volume mounting within user namespaces, directly supporting the advanced rootless capabilities seen in Podman and containerd.

Another notable, albeit subtle, addition is the listing of potentiallyUnsafeConfigAnnotations. This provides a standardized way for runtimes to signal configuration annotations that might alter behavior in unexpected or insecure ways, offering a clearer path for security auditors and developers to assess potential risks. While these updates are highly technical and deep in the weeds, they represent the continuous refinement of the core standards that ensure all OCI-compliant runtimes can deliver consistent, interoperable, and increasingly secure container execution.

Orchestration and Migration: Kubernetes and the Compose Conundrum

The local development story for Docker alternatives, particularly when it comes to multi-container applications and Kubernetes integration, has seen robust evolution, albeit with its own set of challenges.

Kubernetes Integration: CRI-O, containerd, and Podman's Bridge

containerd's role as the primary runtime for Kubernetes via CRI is well-established and has been further hardened by the 2.0 release. For local Kubernetes development, containerd is often used directly or indirectly via tools like kind or k3s.

Podman's story with Kubernetes is distinct. It does not directly implement CRI for kubelet interaction but offers powerful capabilities for developers working with Kubernetes manifests locally. The podman play kube command allows you to deploy a Kubernetes YAML file (for Pods, Deployments, Services, ConfigMaps) directly on a local Podman host, translating Kubernetes objects into Podman pods and containers. This is incredibly useful for local testing of Kubernetes workloads without a full-blown Kubernetes cluster. If you are working with complex configurations, you can use this YAML to JSON tool to validate your manifest structure.

However, podman play kube isn't a full Kubernetes parity solution. It doesn't support all Kubernetes API objects—Services with LoadBalancer type, Ingress resources, or advanced scheduling constraints are notably absent. For anything beyond simple Pod definitions, you'll need a proper Kubernetes distribution. This positions podman play kube as a local development aid, not a production replacement.

The Compose Migration Path: Podman-Compose and Beyond

For developers deeply invested in Docker Compose workflows, the migration to Podman has become substantially smoother. podman-compose, a third-party Python script, provides a compatibility layer that interprets docker-compose.yml files and translates them into Podman commands. While not officially maintained by the Podman project, it covers the vast majority of Compose features.

# Install podman-compose
pip install podman-compose

# Run your existing docker-compose.yml
podman-compose up -d

# Check running containers
podman-compose ps

The more robust alternative, particularly for production environments and CI/CD pipelines, is to leverage Podman's native support for Kubernetes YAML. You can convert a docker-compose.yml to a Kubernetes Pod manifest using podman-compose with the --build flag or use third-party tools like kompose:

# Convert docker-compose.yml to Kubernetes manifests
kompose convert -f docker-compose.yml

# Then run with Podman
podman play kube deployment.yaml

This approach aligns with the broader industry trend of treating Kubernetes manifests as the canonical deployment definition, making local development and production deployments converge on the same configuration language.

Current Realities vs. Marketing Claims

Let's be candid about what works well and what remains clunky in this post-Docker world as of early 2026.

What works reliably:

Rootless containers with Podman have reached production maturity for most workloads.
containerd 2.0 provides a stable, hardened runtime for Kubernetes clusters.
The OCI standards ensure images built with Buildah or Docker work interchangeably.
Podman Desktop offers a usable GUI for developers transitioning from Docker Desktop.

What's still clunky:

Rootless networking via slirp4netns remains slower than rootful alternatives—fine for development, less ideal for high-throughput production scenarios.
The Netavark migration, while beneficial, can catch teams off-guard if they have custom CNI configurations.
User namespace support in Kubernetes, while progressing, still requires manual kernel tuning on many distributions.
Mac and Windows support, while functional via VMs, introduces latency and complexity compared to native Docker Desktop integration on those platforms.

Expert Insight: The Runtime Fragmentation Endgame

Here's my prediction for where this is heading: by late 2026, we'll see a consolidation rather than continued fragmentation. The container runtime landscape will likely settle into a tiered model:

Tier 1 (Orchestration Runtime): containerd will dominate as the Kubernetes-native runtime, with CRI-O remaining a viable alternative for Red Hat-aligned deployments.
Tier 2 (Developer Experience): Podman and Podman Desktop will capture a significant share of local development workflows, particularly in enterprise environments with strict security requirements.
Tier 3 (Specialized Use Cases): Low-level runtimes like crun (a C-based OCI runtime) and youki (Rust-based) will power specific performance-critical or embedded scenarios.

Docker, meanwhile, will continue to thrive in developer tooling and learning environments, but its daemon-based architecture will increasingly be seen as a legacy choice for production infrastructure. The future belongs to daemonless, rootless-first designs—and the tooling is finally mature enough to make that practical.