micro3270

A containerized lightweight multi-architecture compatible 3270 emulator.

Features

• Multi-architecture compatibility for amd64, arm64, and s390x
• OpenShift Container Platform (OCP) and Kubernetes compatible
• Mountable configurations and session files with TLS Support
• Minimized image size: ~40MB

Usage Guide

Run this image using podman with a specified z/OS hostname/ip and port.

Environment Variables

• ZOS_HOST - The hostname or IP address of a reachable z/OS host
• ZOS_PORT - optional, for specifying a non-default telnet port

Directories & Files

• /micro3270 - default directory within container, contains basic installation files
• /micro3270/config - (optional) configuration directory, expected to be volume mounted from container runtime
• /micro3270/config/.c3270 - (optional) configuration file for setting configuration options, will be overwritten by volume mount
• /micro3270/config/cacert - (optional) directory containing TLS certificates

Running Locally

Launch a terminal application and run one of the following commands.

podman run -it icr.io/zmodstack/micro3270 $ZOS_HOST $ZOS_PORT

With additional command-line options

podman run -it icr.io/zmodstack/micro3270 [options] $ZOS_HOST $ZOS_PORT

Running with TLS Certicates

For z/OS environments that require TLS connectivity with self-signed certificates, certificates can be placed in the /micro3270/config directory. This can be done via volume mounting with your container runtime, or through copying files directly into the container's ephemeral filesystem.

Using a "rootless" podman environment where the podman-machine does NOT have access to the local machine's filesystem

# Create new empty volume
podman volume create micro3270-config

# Create a temporary micro3270 container with the volume mounted
podman create --name micro3270 -v micro3270-config:/micro3270/config icr.io/zmodstack/micro3270

# Copy files to container with mounted volume
podman cp </path/to/local/cert> micro3270:/micro3270/config/cacert

# Remove temporary container
podman rm micro3270

# Run the micro3270 container
podman run -it --rm --name micro3270 -v micro3270-config:/micro3270/config icr.io/zmodstack/micro3270 [options] $ZOS_HOST $ZOS_PORT

Skipping TLS Verification

TLS certificate verification may be skipped using the c3270 -noverifycert command-line option.

⚠️ This is NOT recommended and may leave you vulnerable to MITM attacks.

podman run -it --rm --name micro3270 icr.io/zmodstack/micro3270 -noverifycert $ZOS_HOST $ZOS_PORT

Running with Session Profiles

A custom .c3270 session file may be copied into the /micro3270/config/ directory.

To create a local .c3270 session profile, reference the c3270 command-line options and use the "resource format" seen in the Resource and Further Details column.

Create a .c3270 file for a specific z/OS host, e.g. somezoshost.c3270

c3270.caFile: /micro3270/config/cacert
c3270.hostname: some.zos.host.com
c3270.port: 23

! Set additional resource values as necessary
! c3270.acceptHostname: <private-ip>

Copy the somezoshost.c3270 file into your container into the /micro3270/config/.c3270 location.

podman cp </path/to/local/somezoshost.c3270> micro3270:/micro3270/config/.c3270
podman run -it --rm --name micro3270 -v micro3270-config:/micro3270/config icr.io/zmodstack/micro3270