add cookbook for smtprelay

cookbooks/smtprelay/Makefile

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+##
+## Makefile for smtprelay quadlet
+##
+
+DEPENDENCIES = lego
+
+# smtprelay quadlet is mapped to the 10030 user (smtprelay) and 10000 group (itix-svc)
+PROJECT_UID = 10030
+PROJECT_GID = 10000
+
+# Include common Makefile
+include ../../scripts/common.mk

cookbooks/smtprelay/README.md

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+# Podman Quadlet: smtprelay
+
+## Overview
+
+[smtprelay](https://github.com/decke/smtprelay) is a small Golang based SMTP relay/proxy server that accepts mail via SMTP and forwards it to an upstream smarthost (ex: Mailgun, Gmail, ...).
+
+This cookbook:
+
+- Builds a custom smtprelay container image locally, from CentOS Stream 10.
+- Runs smtprelay directly as a dedicated, unprivileged UID/GID (no user namespace mapping).
+- Listens on the submission port (587) with STARTTLS, authenticating clients against a local user/password file.
+- Loads TLS certificates issued by the `lego` cookbook and reloads them automatically when renewed.
+- Includes a timer to periodically rebuild the container image.
+
+## Prerequisites
+
+- Configuration file `/etc/quadlets/smtprelay/smtprelay.ini` must exist.
+- File `/etc/quadlets/smtprelay/allowed_users.txt` must exist, listing the users allowed to relay mail.
+- The `lego` cookbook should be configured to provide TLS certificates.
+
+## Usage
+
+In a separate terminal, follow the logs.
+
+```sh
+sudo make tail-logs
+```
+
+Install the Podman Quadlets and start smtprelay.
+
+```sh
+sudo make clean install
+```
+
+You should see the **smtprelay-build.service** building the smtprelay container image.
+Then, the **smtprelay.service** should start up.
+
+Verify smtprelay is running:
+
+```sh
+sudo systemctl status smtprelay.service
+```
+
+Send a test mail with [swaks](https://www.jetmore.org/john/code/swaks/):
+
+```sh
+swaks --to youremail@example.com --from youremail@example.com --auth-user yourusername --auth-password yourpassword --port 587 --tls
+```
+
+When Let's Encrypt certificates are renewed, the renewal hook automatically restarts smtprelay so it picks up the new certificates.
+
+Restart the **smtprelay.target** unit.
+
+```sh
+sudo systemctl restart smtprelay.target
+```
+
+Finally, remove the quadlets, their configuration and their data.
+
+```sh
+sudo make uninstall clean
+```
+
+## Integration tests
+
+```sh
+sudo make test
+```

cookbooks/smtprelay/SPECS.md

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+# Specification for smtprelay Quadlet Cookbook
+
+You will have to develop a Quadlet cookbook for smtprelay, the mail transfer agent.
+
+## Architecture
+
+smtprelay is a mail transfer agent, deployed as a container image.
+The container image will be built from the CentOS Stream 10 image (`quay.io/centos/centos:stream10`).
+
+## Common requirements
+
+- The `quay.io/centos/centos:stream10` docker image MUST have its own quadlet .image file.
+- Each cookbook MUST have a dedicated unique UID. The GID is 10000.
+
+## Security
+
+Directly set the UID and GID in the quadlet file (no mapping).
+Use the host network, like other quadlet cookbooks.
+Let's Encrypt certificates will be handled by Traefik, so no need to worry about that in the smtprelay cookbook.
+
+## Installation
+
+Create the Containerfile for smtprelay, which will install the smtprelay binary.
+The smtprelay binary can be obtained from the official releases on GitHub: https://github.com/decke/smtprelay.
+
+Look at `cookbooks/base/config/install-fastfetch.sh` for an example of how to install a binary from a GitHub release in a Containerfile.
+
+## Configuration
+
+A sample configuration file for smtprelay:
+
+```ini
+; Hostname for this SMTP server
+hostname = localhost
+
+; File which contains username and password used for
+; authentication before they can send mail.
+allowed_users = /etc/smtprelay/allowed_users.txt
+
+; Networks that are allowed to send mails to us
+; Defaults to localhost. If set to "", then any address is allowed.
+;allowed_nets = 0.0.0.0/0 ::/0
+allowed_nets = 0.0.0.0/0
+
+; Enable TLS for incoming connections on port 587
+listen = starttls://0.0.0.0:587
+local_cert = /etc/smtprelay/tls/localhost.crt
+local_key  = /etc/smtprelay/tls/localhost.key
+
+; Enforce encrypted connection on STARTTLS ports before
+; accepting mails from client.
+local_forcetls = true
+
+; Relay Config (ex: Mailgun)
+remotes = starttls://user:pass@smtp.mailgun.org:587
+```
+
+## Entrypoint
+
+```sh
+smtprelay --config /etc/smtprelay/smtprelay.ini -logfile=/dev/stdout
+```
+
+## How to test
+
+```sh
+swaks --to youremail@example.com --from youremail@example.com --auth-user yourusername --auth-password yourpassword --port 587 --tls
+```
+
+## Useful examples
+
+You can copy the structure of the `miniflux` cookbook.
+Look at the `samba` cookbook for an example of how to handle the container image building.

cookbooks/smtprelay/config/container/Containerfile

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+FROM quay.io/centos/centos:stream10 AS builder
+
+# Tools needed to fetch and unpack the smtprelay release
+RUN dnf install -y curl jq tar gzip \
+ && dnf clean all
+
+COPY install-smtprelay.sh /
+RUN /install-smtprelay.sh
+
+FROM quay.io/centos/centos:stream10
+
+# CA certificates are required to establish TLS connections to the relay host
+RUN dnf install -y ca-certificates \
+ && dnf clean all
+
+COPY --from=builder /usr/local/bin/smtprelay /usr/local/bin/smtprelay
+
+# Submission port
+EXPOSE 587
+
+ENTRYPOINT [ "/usr/local/bin/smtprelay" ]
+CMD [ "--config", "/etc/smtprelay/smtprelay.ini", "-logfile=/dev/stdout" ]

cookbooks/smtprelay/config/container/install-smtprelay.sh

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+#!/bin/bash
+set -Eeuo pipefail
+SMTPRELAY_LATEST_VERSION="$(curl -sSfL https://api.github.com/repos/decke/smtprelay/releases | jq -r '.[] | select(.prerelease == false and .draft == false) | .tag_name' | sort -V | tail -1)"
+SMTPRELAY_VERSION="${SMTPRELAY_VERSION:-$SMTPRELAY_LATEST_VERSION}"
+declare -A ARCH_MAP=( ["x86_64"]="amd64" ["aarch64"]="arm64" )
+arch="$(arch)"
+arch=${ARCH_MAP[$arch]}
+echo "Installing smtprelay $SMTPRELAY_VERSION for $arch..."
+curl -sSfL https://github.com/decke/smtprelay/releases/download/$SMTPRELAY_VERSION/smtprelay-$SMTPRELAY_VERSION-linux-$arch.tar.gz | tar -zx -C /usr/local/bin --no-same-owner smtprelay

cookbooks/smtprelay/config/examples/allowed_users.txt

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+# File which contains username and password used for authentication
+# before clients can relay mail through this server.
+#
+# Format (one user per line, fields separated by spaces):
+#   username bcrypt-hash [email[,email[,...]]]
+#
+#   username:    the SMTP auth username
+#   bcrypt-hash: the bcrypt hash of the password
+#   email:       comma-separated list of "from" addresses the user is
+#                allowed to send as (omit to allow any address)
+#
+# Generate the bcrypt hash of a password with:
+#   python3 -c "import bcrypt; print(bcrypt.hashpw(b'<password>', bcrypt.gensalt()).decode())"
+#
+# Example user "demo" (password "changeme") allowed to send from any address:
+demo $2b$12$V3XmeosOSoI4B.2D8HLzWu7y2YQaoBeF2unnGopZ2ZJJpQ58sKToa

cookbooks/smtprelay/config/examples/smtprelay.ini

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+# -----------------------------------------------------------------------
+# smtprelay configuration - relay-only SMTP server
+#
+# Copy this file to /etc/quadlets/smtprelay/smtprelay.ini and adjust the
+# values for your environment.
+# -----------------------------------------------------------------------
+
+; Hostname for this SMTP server
+hostname = mail.example.com
+
+; File which contains username and password used for
+; authentication before they can send mail (see allowed_users.txt example).
+allowed_users = /etc/smtprelay/allowed_users.txt
+
+; Networks that are allowed to send mails to us.
+; The container uses the host network, so clients connect from outside -
+; allow any address and rely on SMTP authentication instead.
+allowed_nets = 0.0.0.0/0
+
+; -----------------------------------------------------------------------
+; Inbound TLS (certificates provided by the lego cookbook)
+;
+; Replace "localhost" with the actual certificate filename from
+; /var/lib/quadlets/lego/certificates/.
+; -----------------------------------------------------------------------
+
+; Enable TLS for incoming connections on port 587
+listen = starttls://0.0.0.0:587
+local_cert = /etc/smtprelay/tls/localhost.crt
+local_key  = /etc/smtprelay/tls/localhost.key
+
+; Enforce encrypted connection on STARTTLS ports before
+; accepting mails from client.
+local_forcetls = true
+
+; -----------------------------------------------------------------------
+; Outbound relay
+; -----------------------------------------------------------------------
+
+; Relay all mail through an upstream smarthost (ex: Mailgun).
+; Adjust the credentials and host for your provider.
+remotes = starttls://user:pass@smtp.mailgun.org:587

cookbooks/smtprelay/other/lego/smtprelay.sh

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+#!/bin/bash
+
+set -Eeuo pipefail
+
+install -o 10030 -g 10000 -m 0600 -t /run/quadlets/smtprelay/tls /var/lib/quadlets/lego/certificates/*.crt /var/lib/quadlets/lego/certificates/*.key
+systemctl --no-block restart smtprelay.service

cookbooks/smtprelay/overlay.bu

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+variant: fcos
+version: 1.4.0
+passwd:
+  users:
+  - name: smtprelay
+    uid: 10030
+    gecos: smtprelay MTA
+    home_dir: /var/lib/quadlets/smtprelay
+    primary_group: itix-svc

cookbooks/smtprelay/smtprelay-build.timer

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+[Unit]
+Description=Rebuild the smtprelay container image
+PartOf=smtprelay.target
+
+[Timer]
+OnCalendar=daily
+Persistent=true
+
+[Install]
+WantedBy=smtprelay.target

cookbooks/smtprelay/smtprelay.build

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+[Unit]
+Description=Build of the smtprelay MTA
+Wants=network-online.target
+After=network-online.target centos-stream10-image.service
+Requires=centos-stream10-image.service
+
+[Build]
+File=/etc/quadlets/smtprelay/container/Containerfile
+ImageTag=localhost/smtprelay:latest
+SetWorkingDirectory=/etc/quadlets/smtprelay/container

cookbooks/smtprelay/smtprelay.container

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+[Unit]
+Description=smtprelay MTA
+Documentation=https://github.com/decke/smtprelay
+After=local-fs.target network.target smtprelay-build.service lego.target
+Wants=smtprelay-build.service lego.target
+
+# Only start if the main configuration file exists
+ConditionPathExists=/etc/quadlets/smtprelay/smtprelay.ini
+
+# Stop when the target is stopped
+PartOf=smtprelay.target
+
+[Container]
+ContainerName=smtprelay
+
+# Image
+Image=localhost/smtprelay:latest
+AutoUpdate=local
+
+# Security - run directly as a dedicated, unprivileged UID/GID (no mapping)
+User=10030
+Group=10000
+
+# Port 587 is a privileged port (< 1024); grant the capability to bind to it
+AddCapability=CAP_NET_BIND_SERVICE
+
+# Command and arguments
+Entrypoint=/usr/local/bin/smtprelay
+Exec=--config /etc/smtprelay/smtprelay.ini -logfile=/dev/stdout
+
+# Storage
+Volume=/etc/quadlets/smtprelay/smtprelay.ini:/etc/smtprelay/smtprelay.ini:ro,Z
+Volume=/etc/quadlets/smtprelay/allowed_users.txt:/etc/smtprelay/allowed_users.txt:ro,Z
+Volume=/run/quadlets/smtprelay/tls:/etc/smtprelay/tls:Z
+
+# Network
+Network=host
+
+[Service]
+Restart=always
+RestartSec=10
+TimeoutStartSec=120
+TimeoutStopSec=30
+
+# Get the TLS certificates in place before starting smtprelay
+ExecStartPre=/bin/sh -c 'install -o 10030 -g 10000 -m 0600 -t /run/quadlets/smtprelay/tls /var/lib/quadlets/lego/certificates/*.crt /var/lib/quadlets/lego/certificates/*.key'
+
+[Install]
+WantedBy=smtprelay.target

cookbooks/smtprelay/smtprelay.target

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+[Unit]
+Description=smtprelay Service Target
+Documentation=man:systemd.target(5)
+Requires=smtprelay.service smtprelay-build.timer
+After=smtprelay.service smtprelay-build.timer
+
+# Allow isolation - can stop/start this target independently
+AllowIsolate=yes
+
+[Install]
+WantedBy=multi-user.target

cookbooks/smtprelay/tmpfiles.d/smtprelay.conf

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+d$ /run/quadlets/smtprelay 0700 10030 10000 -
+d$ /run/quadlets/smtprelay/tls 0700 10030 10000 -