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to allow the lookup of hosts added to /etc/hosts file via docker options
(issue #51).

.env.example

@@ -5,10 +5,10 @@
 # Optional: (Default value: 587) Port address of the SMTP server to use.
 #SMTP_PORT=
 
-# Mandatory: Username to authenticate with.
+# Optional: Username to authenticate with.
 #SMTP_USERNAME=
 
-# Mandatory: Password of the SMTP user. (Not needed if SMTP_PASSWORD_FILE is used)
+# Optional (Mandatory if SMTP_USERNAME is set): Password of the SMTP user. (Not needed if SMTP_PASSWORD_FILE is used)
 #SMTP_PASSWORD=
 
 # Mandatory: Server hostname for the Postfix container. Emails will appear to come from the hostname's domain.
@@ -17,7 +17,7 @@
 # Optional: This will add a header for tracking messages upstream. Helpful for spam filters. Will appear as "RelayTag: ${SMTP_HEADER_TAG}" in the email headers.
 #SMTP_HEADER_TAG=
 
-# Optional: This will add a header for tracking messages upstream. Helpful for spam filters. Will appear as "RelayTag: ${SMTP_HEADER_TAG}" in the email headers.
+# Optional: Setting this will allow you to add additional, comma seperated, subnets to use the relay. Used like SMTP_NETWORKS='xxx.xxx.xxx.xxx/xx,xxx.xxx.xxx.xxx/xx'.
 #SMTP_NETWORKS=
 
 # Optional: Set this to a mounted file containing the password, to avoid passwords in env variables.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,25 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Reporting a bug**
+
+First of all, this is **not** a problem reporting forum, only report if you are pretty sure what you are experiencing is a bug with this image, not a configuration issue, for that you can use the [Github discussions section](https://github.com/juanluisbaptiste/docker-postfix/discussions) and we will do our best to help you to figure out what's going on with your setup.
+
+Also be sure you are using the latest image by doing _docker pull juanluisbaptiste/postfix:latest_.
+
+**Please include the contents of:**
+
+  * Your docker-compose.yml file
+  * Your .env file file
+
+**Describe the issue**
+Please include a description of what you are trying to accomplish and what you are facing when running this container.
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.

.github/workflows/release.yml

@@ -0,0 +1,48 @@
+name: Release
+
+on:
+  push:
+    tags:
+      - "*"
+
+jobs:
+  docker:
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          token: ${{ secrets.API_GITHUB_TOKEN }}
+
+      - name: Docker meta
+        id: docker_meta
+        uses: crazy-max/ghaction-docker-meta@v2
+        with:
+          images: juanluisbaptiste/postfix
+          tags: |
+            type=semver,pattern={{major}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}.{{minor}}.{{patch}}
+            type=semver,pattern={{version}}
+            alpine
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          platforms: linux/386,linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
+          tags: ${{ steps.docker_meta.outputs.tags }}
+          labels: ${{ steps.docker_meta.outputs.labels }}

.github/workflows/test.yml

@@ -0,0 +1,36 @@
+name: Test
+
+on:
+  push:
+    branches: [master, develop]
+  pull_request:
+    branches: [master, develop]
+
+jobs:
+  build:
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Checkout with token
+        if: github.event_name != 'pull_request'
+        uses: actions/checkout@v2
+        with:
+          token: ${{ secrets.API_GITHUB_TOKEN }}
+
+      - name: Checkout without token
+        if: github.event_name == 'pull_request'
+        uses: actions/checkout@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Docker Build Test
+        run: docker buildx build --load --tag test:test --file ./Dockerfile ./
+
+      - name: Version
+        if: github.event_name != 'pull_request'
+        uses: cycjimmy/semantic-release-action@v2.5.3
+        with:
+          semantic_version: 17.4
+        env:
+          GITHUB_TOKEN: ${{ secrets.API_GITHUB_TOKEN }}

.gitignore

@@ -0,0 +1 @@
+.env

.releaserc.yml

@@ -0,0 +1,11 @@
+---
+branches:
+  - name: master
+  - name: develop
+    prerelease: true
+plugins:
+  - "@semantic-release/commit-analyzer"
+  - "@semantic-release/release-notes-generator"
+  - - "@semantic-release/github"
+    - successComment: false
+      failComment: false

README.md

@@ -3,7 +3,7 @@
 [![Docker Stars](https://img.shields.io/docker/stars/juanluisbaptiste/postfix.svg?style=flat-square)](https://hub.docker.com/r/juanluisbaptiste/postfix/)
 [![Docker Pulls](https://img.shields.io/docker/pulls/juanluisbaptiste/postfix.svg?style=flat-square)](https://hub.docker.com/r/juanluisbaptiste/postfix/)
 
-Simple Postfix SMTP TLS relay [docker](http://www.docker.com) image with no local authentication enabled (to be run in a secure LAN).
+Simple Postfix SMTP TLS relay [docker](http://www.docker.com) alpine based image with no local authentication enabled (to be run in a secure LAN).
 
 It also includes rsyslog to enable logging to stdout.
 
@@ -12,12 +12,11 @@ _If you want to follow the development of this project check out [my blog](https
 
 ### Available image tags
 
-This image has been built on CentOS 7 since its inception, but the new CentOS 8 does [not include supervisor](https://github.com/juanluisbaptiste/docker-postfix/issues/16) anymore, so I have started migrating this image to Alpine linux. So currently there are two image tags available:
+Currently we only handle a rolling release of new versions so only _latest_ tag is available, but there is [work in progress](https://github.com/juanluisbaptiste/docker-postfix/pull/29) to start releasing versioned images to be able to pin to specific versions in production deployments.
 
-  * juanluisbaptiste/postfix:latest, current CentOS 7 based image
-  * juanluisbaptiste/postfix:alpine, new Alpine based image
-
-If testing goes well for some time, then the current CentOS image will be replaced by the new Alpine one, and _latest_ tag will point to it.
+*_NOTES_*:
+  * The _alpine_ tag has been switched to use the master branch, but it's irrelevant as it is the same as _latest_.
+  * Old CentOS 7 based image is avaiable on the _centos_base_image branch_, but it is not being developed any more.
 
 ### Build instructions
 
@@ -26,7 +25,7 @@ Clone this repo and then:
     cd docker-Postfix
     sudo docker build -t juanluisbaptiste/postfix .
 
-Or you can use the provided [docker-compose](https://github.com/juanluisbaptiste/docker-postfix/blob/master/docker-compose.overrides.yml) files:
+Or you can use the provided [docker-compose](https://github.com/juanluisbaptiste/docker-postfix/blob/master/docker-compose.override.yml) files:
 
     sudo docker-compose build
 
@@ -40,8 +39,8 @@ The following env variables need to be passed to the container:
 
 * `SMTP_SERVER` Server address of the SMTP server to use.
 * `SMTP_PORT` (Optional, Default value: 587) Port address of the SMTP server to use.
-* `SMTP_USERNAME` Username to authenticate with.
-* `SMTP_PASSWORD` Password of the SMTP user. If `SMTP_PASSWORD_FILE` is set, not needed.
+* `SMTP_USERNAME` (Optional) Username to authenticate with.
+* `SMTP_PASSWORD` (Mandatory if `SMTP_USERNAME` is set) Password of the SMTP user. If `SMTP_PASSWORD_FILE` is set, not needed.
 * `SERVER_HOSTNAME` Server hostname for the Postfix container. Emails will appear to come from the hostname's domain.
 
 The following env variable(s) are optional.

run.sh

@@ -17,9 +17,8 @@ function add_config_value() {
 if [ -n "${SMTP_PASSWORD_FILE}" ]; then [ -f "${SMTP_PASSWORD_FILE}" ] && read SMTP_PASSWORD < ${SMTP_PASSWORD_FILE} || echo "SMTP_PASSWORD_FILE defined, but file not existing, skipping."; fi
 
 [ -z "${SMTP_SERVER}" ] && echo "SMTP_SERVER is not set" && exit 1
-[ -z "${SMTP_USERNAME}" ] && echo "SMTP_USERNAME is not set" && exit 1
-[ -z "${SMTP_PASSWORD}" ] && echo "SMTP_PASSWORD is not set" && exit 1
 [ -z "${SERVER_HOSTNAME}" ] && echo "SERVER_HOSTNAME is not set" && exit 1
+[ ! -z "${SMTP_USERNAME}" -a -z "${SMTP_PASSWORD}" ] && echo "SMTP_USERNAME is set but SMTP_PASSWORD is not set" && exit 1
 
 SMTP_PORT="${SMTP_PORT:-587}"
 
@@ -33,10 +32,15 @@ add_config_value "mydestination" 'localhost'
 add_config_value "myorigin" '$mydomain'
 add_config_value "relayhost" "[${SMTP_SERVER}]:${SMTP_PORT}"
 add_config_value "smtp_use_tls" "yes"
-add_config_value "smtp_sasl_auth_enable" "yes"
-add_config_value "smtp_sasl_password_maps" "lmdb:/etc/postfix/sasl_passwd"
-add_config_value "smtp_sasl_security_options" "noanonymous"
+if [ ! -z "${SMTP_USERNAME}" ]; then
+  add_config_value "smtp_sasl_auth_enable" "yes"
+  add_config_value "smtp_sasl_password_maps" "lmdb:/etc/postfix/sasl_passwd"
+  add_config_value "smtp_sasl_security_options" "noanonymous"
+fi
 add_config_value "always_add_missing_headers" "${ALWAYS_ADD_MISSING_HEADERS:-no}"
+#Also use "native" option to allow looking up hosts added to /etc/hosts via
+# docker options (issue #51)
+add_config_value "smtp_host_lookup" "native,dns"
 
 if [ "${SMTP_PORT}" = "465" ]; then
   add_config_value "smtp_tls_wrappermode" "yes"
@@ -44,7 +48,7 @@ if [ "${SMTP_PORT}" = "465" ]; then
 fi
 
 # Create sasl_passwd file with auth credentials
-if [ ! -f /etc/postfix/sasl_passwd ]; then
+if [ ! -f /etc/postfix/sasl_passwd -a ! -z "${SMTP_USERNAME}" ]; then
   grep -q "${SMTP_SERVER}" /etc/postfix/sasl_passwd  > /dev/null 2>&1
   if [ $? -gt 0 ]; then
     echo "Adding SASL authentication configuration"