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

Source: Dev.to

The Containerization Landscape (Late 2024 – Early 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.

Below we 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.

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Podman

Daemonless 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.

• No central privileged daemon – Podman runs containers as child processes of the user who invokes the podman command.
• Security implication – If the Podman process is compromised, the blast radius is theoretically contained to the invoking user’s privileges.

Operational Quirks

The “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:

• Generate systemd unit files for individual containers or entire pods with podman generate systemd.
• Leverage systemd’s robust process‑supervision capabilities to manage containers like any other system service.

Note: 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.

Example: Generate a systemd unit for a simple Nginx container

# Run the container
podman run -d --name my-nginx -p 8080:80 nginx:latest

# Generate a systemd unit file
podman generate systemd --name my-nginx > ~/.config/systemd/user/container-my-nginx.service

# 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 Containers

Podman’s standout feature, rootless containers, reached significant maturity throughout 2024 – 2025. This capability allows unprivileged users to build, run, and manage containers without requiring sudo, drastically reducing the attack surface.

• User namespaces – The internal root user (UID 0) is mapped to an unprivileged host UID, defined in /etc/subuid and /etc/subgid.
• Storage – Rootless containers typically rely on fuse‑overlayfs, a FUSE‑based implementation of the overlayfs filesystem. It enables unprivileged layered filesystems but incurs a modest performance penalty compared to the kernel module.
• Networking – Handled by slirp4netns, a user‑mode networking stack that creates a virtual network interface and routes traffic through the host’s network namespace. It avoids privileged network manipulation but often exhibits higher latency and lower throughput than CNI‑based networking used by rootful containers.

Podman Desktop (v1.22, 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

Buildah

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.

• Daemonless – No background service is required; commands run directly against the host filesystem.
• Atomic commands – buildah from, buildah mount, buildah run, buildah commit give you step‑by‑step control over image layers.
• Dockerfile compatibility – buildah bud -t myimage . offers a familiar experience, while still allowing you to drop down to the lower‑level commands when needed.

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 (e.g., gcc, 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 (simplified – normally 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 is powerful but requires a deeper understanding of image layering and filesystem operations than a simple Dockerfile. The learning curve is undeniable.

Supply‑Chain Security Enhancements in Buildah

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—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 only 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 1.35.0 → 1.42.0)

These quality‑of‑life improvements streamline workflows while highlighting the ongoing effort to align with entrenched Docker behaviors.

containerd: The Low‑Level Runtime for Kubernetes

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.

• containerd 2.0 – released late 2024
• containerd 2.1 – released May 2025

Both releases focus on stability, extensibility, and security.

What containerd Does

• Manages the complete container lifecycle: image transfer, storage, and execution.
• Exposes a gRPC API.
• Implements the Container Runtime Interface (CRI) required by the kubelet, making it the de‑facto standard for Kubernetes.

The 2.0 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 critical.

Note: The configuration format changed to v3, requiring a migration step for existing installations (containerd config migrate).

New Features in containerd 2.0

1. Node Resource Interface (NRI) Enabled by Default

   • Provides a powerful extension mechanism for customizing low‑level container configurations.
   • Allows finer‑grained control over resource allocation and policy enforcement through plugins (similar to mutating admission webhooks but operating directly at the runtime level).
   • Its impact will depend on community‑driven plugins; out‑of‑the‑box it is a mechanism, not a solution.

2. Improved User‑Namespace Support

   • Enables containers to run as root inside the container but map to an unprivileged UID on the host, drastically reducing the blast radius of a container escape.
   • Still considered “beta for Kubernetes” as of late 2024; full, stable integration within the Kubernetes ecosystem is a longer journey.
   • Enabling often requires kernel parameters such as user.max_user_namespaces=1048576.

Container Networking: Ongoing Evolution

Container networking remains one of the most complex domains, and the ecosystem continues to evolve toward more flexible and secure models.

• The Container Network Interface (CNI) is 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 the underlying network topology (e.g., veth pairs, virtual bridges) for root‑ful Podman and containerd‑managed containers is consistent and interchangeable across plugins.

Container Networking Overview

• CNI‑compliant runtimes
  The networking model for containers is largely consistent across CNI‑compliant runtimes. However, CNI’s flexibility can also be a weakness: different plugins (e.g., bridge, host‑local, or more advanced ones like Calico and Cilium) expose varying features and complexities.

• Debugging
  Troubleshooting network issues often requires:

  1. Understanding the specific plugin configuration files (usually in /etc/cni/net.d/).
  2. Knowing how the plugin interacts with host‑level networking tools such as iptables or nftables.
     This is not a “set‑and‑forget” situation; it demands hands‑on network troubleshooting skills.

Podman’s Shift from CNI to Netavark

• Background
  Starting with Podman 4.0, the default network backend switched from CNI to Netavark. Netavark is a new network stack written in Go, designed to integrate tightly with Podman’s daemonless architecture.

• Deprecation
  CNI is now deprecated and will be removed in a future major Podman release (≥ 5.0).

• Checking the Backend

  podman info --format {{.Host.NetworkBackend}}

• Implications

  • Netavark provides a more cohesive experience for custom networks and DNS resolution.
  • Existing CNI configurations—especially custom ones—may need to be re‑evaluated and migrated when upgrading Podman.

Rootless Networking

• slirp4netns remains the primary mechanism for rootless containers because unprivileged users cannot manipulate network devices directly.
• This creates a persistent disparity in networking capabilities and performance between rootful and rootless deployments.
• While functional, slirp4netns can add significant overhead for workloads that demand high network I/O or low latency.

Container Security Trends

Least‑Privilege Execution

• Rootless mode (Podman) and user‑namespace support (containerd 2.0) map container root to an unprivileged host user, reducing the impact of a container escape.

• Capability Dropping – Containers often run with a broad default set (e.g., CAP_NET_ADMIN, CAP_SYS_ADMIN). Explicitly dropping unnecessary capabilities tightens the attack surface:

  podman run --cap-drop ALL --cap-add CHOWN myimage

• Mandatory Access Controls – Integration with SELinux and AppArmor adds another layer of protection, but configuring them requires deep OS‑level expertise.

Supply‑Chain Security

• SBOM Generation – buildah --sbom produces a Software Bill of Materials, addressing supply‑chain transparency.

• OCI Image Specification v1.1 (released Feb 2024) adds:

  • subject and artifactType fields.
  • A referrers API for linking external artifacts (signatures, attestations, SBOMs) to an image without embedding them.

  This standardizes metadata handling, improving verifiable image integrity. Adoption by registries and tooling remains the biggest hurdle.

OCI Specification Updates (2024)