# elssh Build Guide – Docker-based RPM Packaging

This document explains how to build **elssh** RPM packages for various Enterprise Linux versions using Docker.

You only need to build the versions you actually require. There is no need to run all commands.

All built RPM packages will be automatically placed in the `./output/` directory on your host machine.

## Prerequisites

- Docker (version 20+ recommended)
- Git
- Sufficient disk space (~10 GB+ recommended)
- Internet connection

## Step 1: Download Sources

You must download the source code and tarballs before building:

```bash
# Download the pinned sources from version.env
./pullsrc.sh
```

> **Note**: Run this command only once before starting any builds. It downloads the single pinned set of sources defined in `version.env`. With `DOCKERBUILD=1 ./pullsrc.sh` only the Perl tarball is fetched (used for EL5 image builds).

## Step 2: Building RPMs for Specific Platforms

Choose only the platforms you need and run the corresponding commands.

### x86_64 Builds

#### For EL5 (CentOS 5)

```bash
# Build Docker image
docker build -t elssh:el5 -f ./docker/Dockerfile.centos5 .

# Build 64-bit packages (recommended)
docker run --rm -v .:/data -e "M32=0" elssh:el5

# Build 32-bit packages (optional)
docker run --rm -v .:/data -e "M32=1" elssh:el5
```

#### For EL6 (CentOS 6)

```bash
docker build -t elssh:el6 -f ./docker/Dockerfile.centos --build-arg VERSION_NUM=6 .
docker run --rm -v .:/data elssh:el6
```

#### For EL7 (CentOS 7)

```bash
docker build -t elssh:el7 -f ./docker/Dockerfile.centos --build-arg VERSION_NUM=7 .
docker run --rm -v .:/data elssh:el7
```

#### UOS 20 Variant (EL8)

Reuse the EL8 image (CentOS Stream 8, `el7/` spec via `GUESS_DIST` mapping) and pass `UOS20=1` to enable the kernel-panic fix in `sshd.c` and prefix `PKGREL` with `uos20.` (so the resulting RPMs are distinguishable from the standard build).

```bash
docker build -t elssh:el8 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=8 .
docker run --rm -v .:/data -e "UOS20=1" elssh:el8
```

The aarch64 UOS20 build (CI artifact `rpm-uos20-aarch64`) uses the aarch64 EL8 image with `-e "UOS20=1"`.

#### For EL8 (CentOS 8 / RHEL 8 / Rocky 8 / AlmaLinux 8)

```bash
docker build -t elssh:el8 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=8 .
docker run --rm -v .:/data elssh:el8
```

#### For EL9 (CentOS Stream 9 / RHEL 9 / Rocky 9 / AlmaLinux 9)

```bash
docker build -t elssh:el9 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=9 .
docker run --rm -v .:/data elssh:el9
```

### aarch64 (ARM64) Builds

#### For EL7 aarch64

```bash
docker build -t elssh_aarch64:el7 \
  --platform linux/arm64 \
  -f ./docker/Dockerfile.centos \
  --build-arg VERSION_NUM=7 .

docker run --rm -v .:/data --platform linux/arm64 elssh_aarch64:el7
```

#### For EL8 aarch64

```bash
docker build -t elssh_aarch64:el8 \
  --platform linux/arm64 \
  -f ./docker/Dockerfile.centos-stream \
  --build-arg VERSION_NUM=8 .

docker run --rm -v .:/data --platform linux/arm64 elssh_aarch64:el8
```

#### For EL9 aarch64

```bash
docker build -t elssh_aarch64:el9 \
  --platform linux/arm64 \
  -f ./docker/Dockerfile.centos-stream \
  --build-arg VERSION_NUM=9 .

docker run --rm -v .:/data --platform linux/arm64 elssh_aarch64:el9
```

## Build Arguments

| Argument          | Values | Description |
|-------------------|--------|-----------|
| `VERSION_NUM`     | 6,7,8,9| Specifies the target EL version (used in most Dockerfiles) |
| `M32` (EL5 only)  | 0 or 1 | `0` = 64-bit, `1` = 32-bit |
| `UOS20`           | 0 or 1 | `1` = build the UOS 20 variant (EL8 image); enables the kernel-panic patch and prefixes `PKGREL` with `uos20.` |

> Note: Standalone Dockerfiles for Amazon Linux / openEuler / Rocky Linux have been consolidated into the generic EL images (reusing EL8/EL9 via glibc compatibility) and are no longer maintained separately.

## Output Location

After each successful build, all built `.rpm` files land directly in `./output/` (flat, no per-version subdirs):

```
output/
├── openssh-*.rpm
├── openssh-clients-*.rpm
└── ...
```

Every build (native `./compile.sh` or Docker via `docker/docker_compile.sh`) funnels through the same copy step, so building another EL version adds to / overwrites the same flat directory — copy the files out first if you need to keep versions separate.

## Quick Start Examples

### Build only for modern systems (EL8 + EL9)

```bash
./pullsrc.sh

docker build -t elssh:el8 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=8 .
docker run --rm -v .:/data elssh:el8

docker build -t elssh:el9 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=9 .
docker run --rm -v .:/data elssh:el9
```

### Build only for ARM64

```bash
./pullsrc.sh

docker build -t elssh_aarch64:el9 --platform linux/arm64 -f ./docker/Dockerfile.centos-stream --build-arg VERSION_NUM=9 .
docker run --rm -v .:/data --platform linux/arm64 elssh_aarch64:el9
```

## Troubleshooting

- **Permission issues**: Run `chown -R $USER output/` after building
- **Docker build fails on first run**: This is normal — it needs to download base images and dependencies
- **ARM64 builds**: Requires a machine with ARM64 support or Docker Buildx multi-platform enabled