add support for build tag to allow to disable some features

The following build tags are available:

- "nogcs", disable Google Cloud Storage backend
- "nos3", disable S3 Compabible Object Storage backends
- "nobolt", disable Bolt data provider
- "nomysql", disable MySQL data provider
- "nopgsql", disable PostgreSQL data provider
- "nosqlite", disable SQLite data provider
- "noportable", disable portable mode

docker/sftpgo/alpine/Dockerfile

@@ -4,19 +4,18 @@ RUN apk add --no-cache git gcc g++ ca-certificates \
   && go get -d github.com/drakkan/sftpgo
 WORKDIR /go/src/github.com/drakkan/sftpgo
 ARG TAG
+ARG FEATURES
 # Use --build-arg TAG=LATEST for latest tag. Use e.g. --build-arg TAG=0.9.6 for a specific tag/commit. Otherwise HEAD (master) is built.
 RUN git checkout $(if [ "${TAG}" = LATEST ]; then echo `git rev-list --tags --max-count=1`; elif [ -n "${TAG}" ]; then echo "${TAG}"; else echo HEAD; fi)
-RUN go build -i -ldflags "-s -w -X github.com/drakkan/sftpgo/utils.commit=`git describe --always --dirty` -X github.com/drakkan/sftpgo/utils.date=`date -u +%FT%TZ`" -o /go/bin/sftpgo
+RUN go build -i $(if [ -n "${FEATURES}" ]; then echo "-tags ${FEATURES}"; fi) -ldflags "-s -w -X github.com/drakkan/sftpgo/utils.commit=`git describe --always --dirty` -X github.com/drakkan/sftpgo/utils.date=`date -u +%FT%TZ`" -o /go/bin/sftpgo
 
 FROM alpine:latest
 
 RUN apk add --no-cache ca-certificates su-exec \
   && mkdir -p /data /etc/sftpgo /srv/sftpgo/config /srv/sftpgo/web /srv/sftpgo/backups
 
-# ca-certificates is needed for Cloud Storage Support and to expose the REST API over HTTPS.
-# If you install git then ca-certificates will be automatically installed as dependency.
-# git, rsync and ca-certificates are optional, uncomment the next line to add support for them if needed.
-#RUN apk add --no-cache git rsync ca-certificates
+# git and rsync are optional, uncomment the next line to add support for them if needed.
+#RUN apk add --no-cache git rsync
 
 COPY --from=builder /go/bin/sftpgo /bin/
 COPY --from=builder /go/src/github.com/drakkan/sftpgo/sftpgo.json /etc/sftpgo/sftpgo.json

docker/sftpgo/alpine/README.md

@@ -13,7 +13,10 @@ sudo groupadd -g 1003 sftpgrp && \
 
 # Edit sftpgo.json as you need
 
-# Get and build SFTPGo image (add --build-arg TAG=LATEST to build the latest tag or e.g. TAG=0.9.6 for a specific tag/commit).
+# Get and build SFTPGo image.
+# Add --build-arg TAG=LATEST to build the latest tag or e.g. TAG=0.9.6 for a specific tag/commit.
+# Add --build-arg FEATURES=<features to disable> to disable some feature.
+# Please take a look at the [build from source](./../../../docs/build-from-source.md) documentation for the complete list of the features that can be disabled.
 git clone https://github.com/drakkan/sftpgo.git && \
   cd sftpgo && \
   sudo docker build -t sftpgo docker/sftpgo/alpine/

docker/sftpgo/debian/Dockerfile

@@ -4,16 +4,18 @@ LABEL maintainer="nicola.murino@gmail.com"
 RUN go get -d github.com/drakkan/sftpgo
 WORKDIR /go/src/github.com/drakkan/sftpgo
 ARG TAG
+ARG FEATURES
 # Use --build-arg TAG=LATEST for latest tag. Use e.g. --build-arg TAG=0.9.6 for a specific tag/commit. Otherwise HEAD (master) is built.
 RUN git checkout $(if [ "${TAG}" = LATEST ]; then echo `git rev-list --tags --max-count=1`; elif [ -n "${TAG}" ]; then echo "${TAG}"; else echo HEAD; fi)
-RUN go build -i -ldflags "-s -w -X github.com/drakkan/sftpgo/utils.commit=`git describe --always --dirty` -X github.com/drakkan/sftpgo/utils.date=`date -u +%FT%TZ`" -o sftpgo
+RUN go build -i $(if [ -n "${FEATURES}" ]; then echo "-tags ${FEATURES}"; fi) -ldflags "-s -w -X github.com/drakkan/sftpgo/utils.commit=`git describe --always --dirty` -X github.com/drakkan/sftpgo/utils.date=`date -u +%FT%TZ`" -o sftpgo
 
 # now define the run environment
 FROM debian:latest
 
 # ca-certificates is needed for Cloud Storage Support and to expose the REST API over HTTPS.
-# If you install git then ca-certificates will be automatically installed as dependency.
-# git, rsync and ca-certificates are optional, uncomment the next line to add support for them if needed.
+RUN apt-get update && apt-get install -y ca-certificates
+
+# git and rsync are optional, uncomment the next line to add support for them if needed.
 #RUN apt-get update && apt-get install -y git rsync ca-certificates
 
 ARG BASE_DIR=/app

docker/sftpgo/debian/README.md

@@ -8,13 +8,22 @@ You can build the container image using `docker build`, for example:
 docker build -t="drakkan/sftpgo" .
 ```
 
-This will build master of github.com/drakkan/sftpgo. To build the latest tag you can add `--build-arg TAG=LATEST`
-and to build a specific tag/commit you can use for example `TAG=0.9.6`, like this:
+This will build master of github.com/drakkan/sftpgo.
+
+To build the latest tag you can add `--build-arg TAG=LATEST` and to build a specific tag/commit you can use for example `TAG=0.9.6`, like this:
 
 ```bash
 docker build -t="drakkan/sftpgo" --build-arg TAG=0.9.6 .
 ```
 
+To disable some features you can add `--build-arg FEATURES=<features to disable>`. For example you can disable SQLite support like this:
+
+```bash
+docker build -t="drakkan/sftpgo" --build-arg FEATURES=nosqlite .
+```
+
+Please take a look at the [build from source](./../../../docs/build-from-source.md) documentation for the complete list of the features that can be disabled.
+
 Now create the required folders on the host system, for example:
 
 ```bash